For Sale National RBL-2 VLF receiver, BC-344-D
Posted by Ronnie Parker AKA ROCK on May 01, 2002 at 10:08:57
I have for sale a National VLF receiver model RBL-2. The unit is in working order and good shape for it's age mid 1940's. The cabnet can use a once over. Some of the paint is flaking off. As you might know this radio is heavy weight 74Lbs. The BC-344-D weight 60Lbs. I would perfer local pick up in southern Connecticut but will ship if need be.
asking $200 for the RBL-2,$150 for the BC-344-D + shipping from 06606. E-mail me for more info.
73's ROCK, N1UDI/Radio
Re: QSL - cards from VLF - stations
Posted by Bohica Zamboni on May 03, 2002 at 04:13:11
Hello Klaus.
Getting QSL cards from American VLF stations is pretty much a matter of luck and chance, in my experience... and with the stations sending almost exclusively encrypted FSK, it's rather hard to even PROVE your reception of thier signals.
I've been doing VLF DXing for a LONG time now, and I've only gotten one QSL card... but, I must admit, it's from the only station that I pursued aggressively enough to actually TRY for a card!
One day I was snooping in the 20 - 25 KHz range, and instead of the usual FSK, I was startled to hear CW telegraphy on the frequency occupied by the now defunct NSS at Annapolis, MD. They were sending 5 letter coded groups at about 20 - 25 WPM. I grabbed a pad, noted the time, and began to copy. I was certain that someone had routed the wrong traffic to the VLF rig (they had a lot of HF circuits running CW at the time), and this was an oddity that I wanted to get a QSL on.
I added a letter, addressed to "Watch Officer", and mailed it to US NAVAL COMMUNICATIONS STATION NSS ANNAPOLIS, MD, never expecting to hear from them.
I was surprised a week or so later to receive an envelope from NSS, containing a letter.
It seems that the watch officer on duty at the time was a ham, and he knew all about SWLs!
At that time (1985) the Navy still had some operators in the Atlantic Fleet who could copy CW, and to keep them in practice NSS sent a weekly CW broadcast, which the fleet ops copied and submitted to the fleet communicator's office. He was sort of amused that an SWL in the middle of the US had copied the drill, ESPECIALLY on 24 KHz! He said he was posting my note, and my copy, on the coffee room bulletin board at the station, to let the other staff know that NSS really WAS being heard
(running 800 KW, I wouldn't think that was the least bit questionable!).
He also included something that HAS to be a one of a kind item... he managed to find an old NSS QSL card (apparently they didn't get too many requests for them), and marked it appropriately as verifying reception of the station, running CW on 24 KHz!
Anyway... I lucked out, and got a VLF QSL. Suppose the watch officer hadn't been a ham? Or suppose the guy was in a bad mood the day my report came in? Or suppose the Post Office didn't bother to figure out who I was writing with my blind address? The result would have been no card.
The only other times I ever came close to a QSL... GBR (16.0 KHz, Rugby, Great Britain) used to break thier encrypted FSK four times a day and go to CW to send time signals to allow calibrating clocks aboard ships in the British fleet. With GREAT effort, I managed to catch them doing it twice,
and after a string of one second time ticks was rewarded with VVV VVV VVV DE GBR GBR GBR in my headphones. Never bothered to send for a card tho... just hearing them, on a terrible antenna in miserable big city industrial noise conditions was good enough for me.
The other time... just scanning around below 20 KHz, I happened to tune in just in time to catch the end of a message in CW; DE JXN JXN JXN AR SK...
I had absolutely NO idea who I'd just heard until several years later. It turns out that JXN is a NATO station operating from Norway; I happened to stumble across the information on the internet while I was looking for something else.
QSLing these guys is worth a try, but keep this in mind; nowadays the vast majority of operators don't know what a QSL card IS. The days when almost all military radio operators came from the ranks of hams is long past. They don't expect to be copied by anyone but thier intended recipients, and it may come as a surprise to them that they CAN be copied. And as I said before, unless you can come up with some sort of readable copy (rather than just noise), you'll have a hard time convincing them that you actually received the station.
Good Luck,
Bohica Zamboni,
The Eccentric Old Man in the Basement of the Radio Band
LW Antenna Tuner Needed
Posted by William C. Walker on May 03, 2002 at 15:47:27
Hello, I have a friend who is going to build a part 15 compliant Lowfer transmitter for the 160 to 190 frequency range. I need to find a antenna tuner that is already built or at least plans and a schematic to build one for that frequency range.
Can anyone offer any help or suggestions?
Re: LW Antenna Tuner Needed
Posted by Clint Turner, KA7OEI on May 03, 2002 at 21:08:49
Hi,
A "tuner" might be an inappropriate term for what you need: What you need is something more along the lines of a matching network located at the antenna.
Because part 15 states that "The total length of the transmission line, antenna, and ground lead (if used) shall not exceed 15 meters" it would make the most sense to put the transmitter at the base of the antenna: You wouldn't want to waste "valuable footage" in a feedline that could be better-utilized as part of your antenna.
If you are using a vertical, your matching network will consist of a large coil in series with the antenna - to cancel out the capacitive reactance - and leave you with a resistive component.
If you are *really* unlucky, you will end up at 50 ohms: A "reasonable" LowFER antenna will likely have a feedpoint resistance in the area of a few ohms to a couple 10's of ohms after the loading coil - ideally being well into small fractions of ohms if your matching network and ground were *really* effective.
At this point, a matching network will also have some means of transforming the impedance at the feedpoint to the impedance of the transmitter. Two ways of accomplishing this might be:
- Designing your transmitter to have the necessary output impedance. This could be as simple as having a multiple-tapped transformer incorporated into the final amplifier section of the transmitter. One could also construct an autotransformer that operates outboard of the transmitter's final section.
- Have an external LC matching network. Mark Mallory (LowFER MPM) suggested years ago that a 3 element lumped-constant 1/4 wave matching network was a good way to go, as it had several advantages: It reduced harmonics somewhat so that LowFER harmonics wouldn't be as much of a problem in the HF bands. He also pointed out that an odd-numbered network like that operated as an "impedance inverter" and helped smooth out slight mistunings and slightly increased operational bandwidth by virtue of the fact that it tended to mitigate the reactance when the antenna was slightly off-resonance. Care must be taken with using a network of this type with certain types of tuned-output transmitter (like Class-E) to avoid degrading efficiency.
The easiest one to use is probably the first one: If you have, say, a 50 ohms output on your transmitter, you'd first set up the transmitter for 1 watt input and note the voltage and current into a 50 ohm resistive load. You'd then connect your antenna (adjusted to resonance, through the loading coil) and find the tap that caused your transmitter to pull the same amount of current. More than likely, this will be a pretty good match - and this can be easily verified if you are seeing high voltage on the antenna and reasonably high RF current at the base of the antenna immediately following the loading coil.
In general, a "good" LowFER antenna (with 1 watt input to efficient finals) will run at 150-300 mA, while a "really good" one will be closer to an amp - but that latter figure implies fanatical devotion to reducing ground and loading coil losses - probably the two things that contribute most to losses of a LowFER transmitting station.
Clint, KA7OEI (CT)
Re: LW Antenna Tuner Needed
Posted by William C. Walker on May 04, 2002 at 11:17:59
Clint, thanks for the advice. I will pass it along to my friend and we'll see what he comes up with.
I see that you are in CT, so am I at least for now. When we get the LW station up and running this Fall I'll notify you so that you can try to tune it in.
Long wave voice transmitter inquiry (Re: micro-broadcasting)
Posted by J. Jason Wentworth on May 05, 2002 at 07:59:28
Dear Sirs,
My name is J. Jason Wentworth, and I live in Fairbanks, Alaska. I have been gathering information on "FCC Part 15-legal" transmitters with the goal of establishing a low-power community radio station to broadcast local news and views not adequately covered by our single newspaper.
The FCC rules for license-free 160 kHz - 190 kHz long wave transmitters are more generous than I had expected, and I am interested in setting up a long wave voice transmitter (with an audio bandwidth between 4.5 kHz and 10 kHz) for the station. I have so far been unable to find any schematics for such a transmitter. Do you know of any schematics (or perhaps even commercially-available transmitters of this type)? I know that a 10 kHz bandwidth would take up 1/3 of the entire frequency allocation, but as far as I know there are no other 160 kHz - 190 kHz long wave transmitters in my area.
Short wave receivers (many of which will receive down to 150 kHz) are pretty common in Alaska, so I think I could achieve good market penetration. Also, I plan to distribute low-cost long wave receivers such as the Coby Electronics ( http://www.cobyusa.com *) CX-CB12 AM/FM/LW/SW1-9 12 World Band Receiver to increase the number of listeners.
(* Ed. Note: This URL is graphics intensive and can take quite a while to load. It's also heavily dependent on frames and Javascript, and will ignore your browser's Stop button if you get tired of all the pre-loading before anything displays! Not particularly user-friendly, and not much detail once you get there. If you're on a dialup connection, you may want to skip ahead to the product index page for the radio at: http://www.cobyusa.com/personamfm/cxcb12.htm )
I would be most grateful to you for your help. -- J. Jason Wentworth
Re: LW Antenna Tuner Needed
Posted by Clint Turner KA7OEI on May 05, 2002 at 18:43:24
Hi.
Good luck on help in getting the station on the air.
Actually, my initials are CT - not my location: *That* would be UT.
Clint
Re: Long wave voice transmitter inquiry (Re: micro-broadcasting)
Posted by John Davis on May 05, 2002 at 18:49:43
Hi Jason,
Sounds like an interesting project, and it might be workable. I would caution you, though, not to have too high an expectation of coverage.
Even though the FCC Rules appear to be more generous at LF, remember that the wavelength is longer and therefore the antenna efficiency is a lot lower than at MF. So, ten times the power and five times the antenna length do not necessarily result in more range.
If you take extra pains to create a very good ground system, you can transmit AM in this band over a few miles distance. Local electrical noise will affect just how good the reception is, though, and whether people will be willing to listen.
There was an amplitude modulatable 160-190 kHz transmitter in Popular Electronics in late 1971 or 1972, but it could be better with regard to modulation depth. Ed Gelinas operates an AM LowFER in Sunnyvale, CA, using a tube-type transmitter of his own design. I haven't seen a schematic for it, but I have heard a tape of reception from it. The final is a 6AK5, modulated with a hi-fi output transformer, and the quality is extraordinary.
You could also achieve good fidelity with a solid-state transmitter. I would base it on the Simple LowFER Transmitter design of Lyle Koehler. There's a link to his site in our pages (from the LWCA home page, click the LowFER/MedFER icon, then the About Part 15 link, and scroll down to the links).
If you use that design, I'd suggest tailoring the output network and antenna loading so that you could achieve one watt DC input with 6-7.5 V supply voltage. You could then use a power Darlington transistor, operated from a 12-15 V supply, as a series modulator.
Something like this appears to be how the North Country Radio AM-88 kit modulates the final. (That kit, by the way, covers 150 kHz up to the 160 meter ham band, but can only manage about 200 mW in AM mode. It might make a good exciter for a home-built final with its own separate modulator, though.)
Because of the inherent inefficiencies at LF (both on the transmit and receive ends), and because you already have in mind a listener base possessing multiband receivers, another possibility suggests itself--the 22 meter band, which is also discussed briefly in the About Part 15 page.
You may be discouraged at first to realize that the signal strength limit at 13.56 MHz works out to 1.8 mW transmitter output and a quarter-wave groundplane antenna. But consider that at LF, you're only going to radiate microwatts due to the antenna limitation. So, 13.560 MHz actually gives the best radiated field strength of any Part 15 band below UHF! And, there's no limit on how high you can mount the antenna above ground; except for FAA regulations, of course.
The drawback of this band: it's used by medical and industrial diathermy equipment. If there's very much of that gear around Fairbanks, you'll have all sorts of hums and buzzes in the band. If that equipment is well designed and shielded, your signal may be able to overcome it in most neighborhoods. So, this could be a good adjunct to your LF plans. If it's ancient and poorly shielded--well, as the New Yorkers say, fuhgedaboudit.
For 22 meter transmitter ideas, I would recommend a basic crystal oscillator driving a simple diode ring modulator, followed by a good harmonic filter (spectrum purity requirements are heavier at this band, which is reasonable considering how much more signal you're permitted to radiate in the first place). The oscillator should be capable of +10 dbm output, plus whatever loss is inherent in the ring modulator.
Lyle's page, mentioned above, is also one source of ideas for this HF band. Look in his solderless breadboard projects page. Another source of 13.560 MHz ideas would be:
http://home.att.net/~weatheradio/HFtransmit.htm
An important point in either band: remember that the bandwidth of an AM signal is *twice* the maximum audio modulating frequency. That means if you plan to confine your emissions to a 10 kHz bandwidth, you would need to limit your maximum audio frequency response to 5 kHz with a reasonably sharp filter, and place your carrier at least 5 kHz from the edge of the band.
You could have somewhat greater audio fidelity if you're willing to confine the carrier even closer to the center of the band. That's usually feasible at LF. In the 22 meter band, though, the total band is only 14 kHz wide, so if you are able to place the carrier right on 13.560, you could use 7 kHz audio--but if you have to place the carrier a couple kHz away due to interference, then you'd have to scale back the audio response accordingly to keep your sidebands within the Part 15 band.
I hope this gives you a place to start. Maybe others will have some diagrams they'd be willing to share (and perhaps even post here).
John
TLTX freq. change to 13.55983MHZ
Posted by Tony Levstik on May 06, 2002 at 09:19:34
HIFER TLTX now on 13.55983MHZ.
That's down 170Hz from it's currently published Frequency.
Will still be on Weekends and running QRSS3 and RTTY.
Tony L.
TAG Off the Air
Posted by John Andrews on May 06, 2002 at 09:19:56
TAG will be off the air for a while, as lawn-mowing has required the removal of some wiring to the PA.
John Andrews, W1TAG
Re: LW Antenna Tuner Needed
Posted by Lyle Koehler on May 06, 2002 at 11:39:12
Actually, the best LowFER antennas I'm aware of (OK and TEXAS, neither of which is on the air any more) had combined ground and loading coil losses of about 10 ohms. It is very difficult to do much better than that.
As Clint points out, the best form of antenna "tuner" is a series inductance to tune out the reactance of the antenna, plus some means of transforming the impedance to whatever the transmitter wants to see. If the antenna feed impedance is lower than the transmitter impedance (which is what you hope for), the transformation can be achieved with a simple shunt inductance or capacitor across the feed point. A slight retuning of the loading coil is needed when you add the shunt element -- less loading coil inductance when you use a shunt inductor; more inductance when you use a shunt capacitor. The same trick is used on ham mobile antennas, and the appropriate formulas are given in the mobile section of the ARRL Antenna Book. A shunt capacitor is convenient because it's compact and you can go out and buy one ready made. However, a shunt inductor has the advantage that it provides a DC path to ground, which helps to protect the transmitter from electrostatic discharge.
Here are the values of shunt inductance or capacitance needed to transform various antenna impedances to 50 ohms at a frequency of 185 kHz. Values are not critical (an exact 1:1 SWR is no more necessary on LF than on the ham bands), and the nearest stock values of capacitor are given in the table.
Ed. Note: - We apologize for the missing information. Lyle's table was apparently truncated in the automated assembly of the original archive, and the original message is no longer available.
Re: LW Antenna Tuner Needed
Posted by William C. Walker on May 06, 2002 at 14:04:01
Looks like that fellow in Alaska has the same idea that I have. Nice to see some interest in LW broadcasting and since the part 15 frequencies are all but unused we'll find no real competition or interference on those channels.
Clint, can you tell me where these circuits you talk about can be found?
Re: TAG Off the Air
Posted by G. Elmo (Wild Bill) Marconi on May 06, 2002 at 17:21:21
:: TAG will be off the air for a while, as lawn-mowing has required the removal of some wiring to the PA. ::
Lawn mowing??? Clearly, someone's priorities aren't in the right place...
Re: TAG Off the Air
Posted by John Andrews on May 06, 2002 at 21:26:26
Dear Wild Bill:
It appears that a message intended for the Lawn Wiring Club of America was inadvertently posted at this site. I regret the intrusion, and promise I will be mower careful in the future. Have a mekky month of May.
John A.
Re: TAG Off the Air
Posted by Wild Bill Marconi on May 07, 2002 at 04:21:56
:: It appears that a message intended for the Lawn Wiring Club of America was inadvertently posted at this site. ::
A perfectly natural mistake. Who knew there were two LWCAs? And both with the same objective--getting as much metal as possible into the ground.
Re: Long wave voice transmitter inquiry (Re: micro-broadcasting)
Posted by J. Jason Wentworth on May 07, 2002 at 09:58:44
John Davis wrote:
(All quotes missing from post.)
Actually, I'd like to simulcast on LF and MF (the transmitters are cheap enough to permit me to do both). The LF groundwave would blanket our valley, and it might also reach people on the other side of the surrounding hills.
I hear virtually no noise on either my powered AM receivers or my crystal sets that use a 30 meter outdoor wire antenna. We only have four AM stations here (at 660, 820, 970, and 1170 kHz), so the AM band is very quiet between stations.
I usually think in terms of solid-state equipment, but I wouldn't be averse to using a robust tube unit.
Lyle Koehler also suggested this transmitter (suitably modified for voice transmission).
I fear that's a bit beyond me to design. I've built receivers, but I've only built two small, simple AM transmitters, over 20 years ago.
It would also need more modifications to enable it to transmit voice (it's CW-only on LF).
I've looked at this, but I don't think it would be as good for reaching local listeners because of the weaker ground wave. I can't put up a very high antenna, so pure line-of-sight coverage would be very limited. That's why I'm attracted to long wave--the ground wave will blanket our valley. Also, there is a lot of local noise on several of the higher SW bands, while the lower bands and the AM broadcast band are quiet here.
Indeed. I'm going for a talk format (no music except as background audio), so an audio frequency response of 5 kHz would be acceptable.
Yes, I favor 170 kHz or 175 kHz for this reason.
Indeed it does! If anyone has plans for an LF voice transmitter with the above parameters, I'd rather build a proven design than try to re-invent the wheel. The same is true for the antenna/ground system -- Jason
Re: Long wave voice transmitter inquiry (Re: micro-broadcasting)
Posted by John Bogath on May 07, 2002 at 16:34:56
This is a very interesting discussion you have going on here Jason. I'd like to put in "2-cents" more. For my first "penny", why not consider FM ? The receiver FM- discriminator may go a long way toward making your broadcasts more enjoyable to listen to by naturally reducing AM-based noise. For my second "penny", I like the vacuum-tube transmitter idea. A tube won't burn out every time a large static-charge builds on your antenna, like solid-state devices tend to. Good luck.
Re: Long wave voice transmitter inquiry (Re: micro-broadcasting)
Posted by John Davis on May 07, 2002 at 20:03:12
Hi Jason,
The disappearance of quoted passages between left-caret and right-caret brackets is mentioned in the Message Board FAQs. It's a security measure, made necessary by the fact that this is an open board. It's harder for hackers to slip in extraneous HTML or potentially harmful scripts.
You can put < and > characters into text manually as entities:
< > (respectively)
These will be displayed graphically by the browser as < and > but cannot act as brackets for tags or anchors, etc.
Without the quoted passages, I'm not entirely sure of the correct response for some parts of your followup; but if I perceive correctly, you may be selling the groundwave signal (more correctly, direct wave in this case) a bit short at 13.560 MHz. It's a lot stronger outside the antenna's near-field region than the LF or the MF will be, and is only partially limited by line of sight.
Of course, if you are not able to achieve much height for it, it's true that it could become too weak to overcome interference. But I still suspect it might be a productive experiment.
If you'd care to try again on some of the topics that appear to be about capabilities of particular transmitters or modifications that might be needed to them, feel free to try again. Someone might have some specific solutions.
John
QRS 3.17 Download Link Fixed
Posted by Webmaster on May 07, 2002 at 22:31:30
Thanks to Steve Olney for pointing out that the download link for Rik Strobbe's new version of QRS, recently made available through the Longwave Home Page (www.lwca.org) was in error.
The final page before downloading resides on an AOL server for ease of visitor counting, and an unfinished version of the page was accidentally loaded there with the wrong URL for the zip file.
It has now been fixed. Please feel free to check out Rik's newly improved and debugged version.
73,
John
Album dedicated to low frequency community
Posted by Pete Jackson on May 08, 2002 at 11:38:40
Just thought that some of you would like to know that a band in Britain called Chimp have released an album called "Lowfer" which was inspired by the experimental radio community. We really liked the idea of a big community of people messing around at the lowest end of the spectrum! Thanks to all of you for the inspiration
Cheers
Pete Chimp
Re: Long wave voice transmitter inquiry (Re: micro-broadcasting)
Posted by J. Jason Wentworth on May 09, 2002 at 03:20:12
Posted by John Bogath on May 07, 2002 at 16:34:56:
^This is a very interesting discussion you have going on here Jason. I'd like to put in "2-cents" more. For my first "penny", why not consider FM?^
FM is unfavorable for three reasons:
(1) Low-power FM stations aren't allowed to operate as for-profit stations, which is what I want to do;
(2) FM reception is by line-of-sight, and I cannot put up an antenna higher than 15 meters or so;
(3) LPFM stations can only apply for licenses during narrow "window" periods; Also, the nearest FCC office is in Anchorage, several hundred kilometers away.
^The receiver FM- discriminator may go a long way toward making your broadcasts more enjoyable to listen to by naturally reducing AM-based noise.^
That's true, but fortunately we have very little noise on the AM band here in Fairbanks (just a faint "white noise" between stations). We only have four AM stations at 660 kHz, 820 kHz, 970 kHz, and 1170 kHz. I can even clearly hear a 525 kHz, 1 kW long wave non-directional beacon (Ice Pool, ICW) on my pocket AM radio.
^For my second "penny", I like the vacuum-tube transmitter idea. A tube won't burn out every time a large static-charge builds on your antenna, like solid-state devices tend to. Good luck.^
I share your affinity for vacuum tube equipment (it's often easier to troubleshoot than solid-state equipment--just follow the fire!). :-) However, due to the short permitted antennas for Part 15 LW and AM stations, the transmitter has to be outside, right at the antenna. The temperatures here vary between about -50 °C and +30 °C. (-40 °C and -40 °F are the same.) I can build a temperature-controlled box to house the transmitter, but moisture condensation could be a problem for a tube transmitter. Or it might not be--the heat from the tubes could help keep the box interior warm and dry. I've never tried tube equipment in such an environment. (Pocket transistor radios work fine at -50 °C for a few minutes, until the batteries get cold and stop producing current.) -- Jason
Balloon-borne Hifer beacon
Posted by Robert Rochte on May 09, 2002 at 15:09:46
Hello all. I am the Technical Coordinator at an independent K-8 school in the Detroit area. I'm working on a solar Montgolfiere (i.e., hot air balloon) project with some of our students and I am considering flying a Hifer beacon onboard.
First, a little background on the project: Our first free flight balloon will be about 3.5m in diameter and should float at about 15km (50k feet) from late morning until sundown. Net payload capacity for this vehicle is about 500g (1 lb or so).
Some specific questions about a Hifer in this context:
1. Is it likely that anyone will actually copy our beacon? Is there a sufficiently large base of people monitoring such transmissions (i.e., "is anyone out there")?
2. Does anyone have any suggestions about transmitter and antenna design for such an application? I'm a technical person but not particularly experienced in electronics construction, etc., so any help at all would be much appreciated! (Have an old Hifer experiment that you'd like to donate?? :-) )
3. The only receiver that I have available is a cheesey $99 shortwave radio (no BFO and tuning in 5khz increments, I think). Are there any cheap alternatives to a full-blown (and out of my budget) receiver? If there are enough people monitoring who can report contacts back to us, then maybe I don't even care - but it would be neat to have something for the kids to operate themselves. Any way to make this radio do the job?
4. Looking forward to our summertime projects where I will have greater payload capacity (but always below 4-5 lbs to avoid FAR 101 regs), is it possible to send "live" (but buffered, of course) data using QRSS/BPSK/etc.? For example, GPS coordinates? Since our flights are much longer than the average helium weather balloon variety, I don't mind if it takes 45 minutes to receive one location fix. How about a very light implementation of SSTV?? (I know, stretching it really far here!)
Thanks so much for any input!
Regards,
Robert
--
Robert Rochte Technology and Network Coordinator The Grosse Pointe Academy Tel. +1 313-886-1221 x155
U.S. 136 kHz allocation closer...
Posted by John Andrews, W1TAG on May 10, 2002 at 14:44:07
The FCC will be issuing a Notice of Proposed Rulemaking for an Amateur allocation from 135.7 to 137.8 kHz. See:
http://www.arrl.org/news/stories/2002/05/10/100/?nc=1
John Andrews, W1TAG
Since when is LOWFERS allowed in the USA?
Posted by Berger on May 10, 2002 at 17:51:06
Since when is LOWFERS allowed in the USA? In what other countries is also LOWFERS (or something similiar) exist?
What was the idea of allowing LOWFERS?
Why were these frequencies not allocated for high power broadcasting as in Europe?
Re: U.S. 136 kHz allocation closer...
Posted by James J. Wentworth on May 10, 2002 at 18:12:45
This is good news! I had feared that the FCC would reallocate the 160 kHz - 190 kHz band to hams as well, which would spell the end of unlicensed LowFER activities. I say, "God bless the hams," but there should always be portions of the spectrum where people can experiment at low power without licenses.
What do you all think about allocating a portion of the spectrum around 73 kHz to hams? Hams in other countries (particularly in Europe) have been granted this slice-o'-spectrum. -- Jason
Re: Since when is LOWFERS allowed in the USA?
Posted by John Davis on May 10, 2002 at 19:03:22
:: Since when is LOWFERS allowed in the USA? In what other countries is also LOWFERS (or something similiar) exist? ::
These two questions depend upon how a person defines LowFER. The name was invented in the United States in the early 1970s, and originally meant people who use the license-free provisions of the FCC Rules to operate experimental low-power transmitters in the 160-190 kHz frequency range. Those rules have been in effect since the mid 1950s, I believe.
In that sense of the word, LowFERs only exist in the United States and Canada.
However, when licensed amateur radio operators in various countries of Europe and the Pacific region began receiving authorizations to operate on longwave frequencies, it seemed natural to apply the name to them as well. There are ham radio LowFERs in dozens of countries now. Visit the LF Ham and Digital Modes link at the top of the Longwave Home Page (www.lwca.org) for a list of countries.
:: What was the idea of allowing LOWFERS? ::
The original LowFER longwave frequencies were intended for short-range devices such as garage door openers. Experimenters were intrigued by the communication possibilities, and expanded their coverage distances dramatically by paying careful attention to system losses and by using advanced reception techniques.
:: Why were these frequencies not allocated for high power broadcasting as in Europe? ::
You may want to use the Message Board search feature, accessible through the Message Center Lobby, to hunt for earlier discussions on longwave broadcasting and why it is not part of the allocation tables in the Americas. Military and commercial navigation and communication users needed this part of the spectrum more than broadcasters, in the view of our early regulatory agencies.
There are fewer such users below 190 kHz now, but there is also little market demand for long-range but low-fidelity audio broadcasting here, either. The maritime users who remain do not receive interference from LowFERs, nor are they likely to be bothered by amateur radio when such operation is finally authorized here.
Re: LW Antenna Tuner Needed
Posted by mike koscak on May 10, 2002 at 21:53:16
just a note; in commercial installs, typically 25-50watts output, 2 large load coils in series are used, in a simple vetical of 25' or a cage ant. of apx 40' using 4 wires 90 deg. apart 10' wide. you won't really get much static buildup on a small ant unless you have 50mph winds. then a static drain choke is used. In broadcast towers that are ungrounded,a pair of 'johnny balls' spark gap and a single layer coil 4" dia 12" long wound close with #20 is the static drain. I use a art-13 lf vfo on am and lots of coil to open wire line tied together, a wire on top, horizontally does not radiate (only vertical will, for the gnd wave)gives some capacity over gnd. a cage ant does the same, and is more efficient.The old pop elec article used a 12au7, but the tank was scrambled would with thin wire. don't think it got far. the coil R would be more than the ant!. hence the use of large copper tubing or litz wire for your coil to keep loss down.example; crummy coil-r=20 ohm reactive (not d,c.)ant; vert. 6 ohms. output= milliwatts. coil just chewed up your power.(good coil,2 ohms)
GWEN Recordings
Posted by Les Rayburn on May 11, 2002 at 03:17:17
I'm seeking anyone who may have recorded test transmissions from the old GWEN (Ground Wave Emergency Network) that was active on longwave during the 1980's.
Especially interested in getting recordings of any test voice messages that were transmitted...
but digital or Morse recordings are great too.
MP3 if possible, will pay postage, dubbing costs, etc.
73,
Les Rayburn, N1LF
4919 Cox Cove Helena, AL 35080
Re: Balloon-borne Hifer beacon
Posted by Mark Garrett on May 11, 2002 at 10:39:29
I was curious Robert if you are planning on running other transmitters on board your project? Also are you looking to recover your package after it comes down at night? Are you a Amateur or one of the people in your group?
One pound of lift is not that much so you will be limited to simple lightweight wire antennas fastened to the trailing string that will carry your transmitter.
If you are an amateur or one in your group you can use a small one or two transistor amp or even a clock osc out of a computer that falls into the amateur band as a secondary transmitter. These transmitters can be built lightly including battery and since they are a secondary transmitter at a higher frequency you can use small directional antennas to track the package. Radios could them be of a ham radio nature and usually come with operators that would be willing to assist in your project.
There have been many ham radio flights that include GPS, cross band repeaters, Amateur television with several cameras on board and groups dedicated to launching, tracking and recovery of the packages.
Your project sounds interesting and unique in the fact that you are looking at a long term flight time rather than the typical 90 minute flights from helium balloons. If you would like to take this off the board and e-mail me directly I can see who is in your area to assist you.
Saving Part 15 Lowfer
Posted by William C. Walker on May 11, 2002 at 22:14:22
I have heard several rumors that the ARRL is considering a petition to take the 160 to 190 frequency range for Ham enthusiasts.
Does anyone have any information on this subject? It seems to me that the Ham community has quite a bit of space in the SW spectrum and with the new 136 khz allocation on the horizon they are going to add to that space.
Why would they want to utlize the part 15 spectrum and would it be wise to try to mount a "save the lowfer" campaign to nip this in the bud?
Inductive "assist" loop antenna for WWVB radio clocks?
Posted by J. Jason Wentworth on May 12, 2002 at 08:21:26
Hello All,
Recently I have seen several interesting WWVB-controlled clocks and watches that are made by various manufacturers. The product descriptions say that they will not work in Alaska or Hawaii. However, on the NIST (WWV & WWVB) web site, they state that: "We have also heard several reports from Alaska that the clocks work fine, even though Alaska is outside the coverage area shown on the maps. This is probably due to the low amount of radio "background" noise found in a sparsely populated area."
I think an inductively-coupled loop antenna (similar to a Select-A-Tenna but made for 60 kHz) would get enough signal to the WWVB-controlled clocks and watches to enable them to work reliably in Alaska and Hawaii. How could I build such a 60 kHz loop of a reasonable size (75 cm - 100 cm or so in diameter)? I'd like to build a 60 kHz loop that would be small enough that it and a WWVB-controlled clock could be placed on a "Lazy Susan" and rotated until the clock's receiver could "hear" WWVB.
Many thanks in advance to anyone who can help. -- Jason
Re: Saving Part 15 Lowfer
Posted by John Andrews, W1TAG on May 12, 2002 at 10:04:06
William,
The petition for amateur allocations at 136 and 160-190 kHz was filed several years ago. Presumably because of concern about interference to power line carrier systems operating in the 160-190 kHz range, the FCC chose not to propose that allocation. They will shortly release a Notice of Proposed Rulemaking for the 136 kHz band only. This would appear to leave 160-190 kHz "as-is."
Presumably, the only effect on Lowfer operation will be the distraction of spending time on 136 kHz stuff.
John Andrews, W1TAG
Re: Inductive "assist" loop antenna for WWVB radio clocks?
Posted by Lyle Koehler on May 12, 2002 at 11:01:32
The problem isn't in building the loop, but in tuning the darned thing. A passive loop works fine for enhancing MW or LW reception by ear, because you get instant feedback telling you when the loop is tuned and positioned correctly. In the case of the clock, there is of course no audio output, and even in the "lower 48" it might take several minutes for the clock to show an indication that it has acquired the WWVB signal.
Reg Edwards' RJELOOP3 program, available at http://www.btinternet.com/~g4fgq.regp/ can be used to design the loop. As an example of something that might work, I tried plugging in the following numbers:
Length of 1 side of square loop = 305 mm (12 inches)
Number of turns = 105 Wire diameter = 0.4 mm (#26 AWG)
Ratio of winding pitch/wire diameter = 1.1 Frequency = 60 kHz
Reg's software predicts that this loop would need about 1090 pF in parallel to tune it to resonance. You could use a 1000 pF fixed capacitor in parallel with a tuning capacitor salvaged from an AM transistor radio (the oscillator section is usually 60 pF and the antenna section is 140 pF; both sections in parallel = 200 pF maximum). Tuning would involve orienting the loop with the plane of the winding pointed toward Colorado; then tweaking the tuning capacitor a little at a time and waiting a couple of minutes to see if the clock shows any sign of signal acquisition.
Re: Inductive "assist" loop antenna for WWVB radio clocks?
Posted by John Davis on May 12, 2002 at 15:51:31
Lyle makes a very good point about tuning being the tricky part of using a loop for something like this.
You might even want to try a trick we use at one of the TV and radio transmitter sites I supervise. It's in a building that had air terminals added around the roof and a network of cables tying them together. Those, along with the ground cables at several points along the exterior walls, formed a very effective Faraday shield around the building from about the 160 meter ham band on down to VLF.
To get our WWVB clock to work, we simply ran a longwire antenna outside, brought the signal inside via coax, and couple to the clock's own loop with a single turn. No tuning needed. If you have room for a longwire, that may help; or, consider an active whip antenna whose output could also be coupled to the clock in that fashion.
John
Re: Inductive "assist" loop antenna for WWVB radio clocks?
Posted by J. Jason Wentworth on May 12, 2002 at 18:58:23
Thank you both very much for this information! Lyle, Reg Edwards' "plug in" loop design program is just what I needed, because I'm also interested in building a 150 kHz - 300 kHz loop to assist my Coby LW/SW/AM/FM receiver on long wave. The small WWVB loop would be perfect for use at work, where we need the exact time to which to set the airport parking lot gate clocks.
John, I have a question about your long wire antenna solution. I have an existing ~35 meter length of RG-6 coax (an abandoned cable television line disconnected at the utility pole) that I use as an AM and shortwave long wire antenna. When you said that you coupled the long wire to the clock's own loop with a single turn, did you physically wind it around the little loopstick inside the clock or did you make a larger loop that you placed near the clock? Either way, my coax long wire antenna should work fine for home use. The outer braid might even shield the inner conductor from the local AM signals so that the clock's receiver could more easily "hear" WWVB. -- Jason
Hifer PBJ temporarily off air
Posted by Chris Waldrup on May 13, 2002 at 21:25:36
I just lost the antenna that PBJ uses at 13.55787 due to a ferocious lightning and wind storm. It will probably be at least next week before I can get it repaired. I will post when I am back on.
Chris
LF Ham Band
Posted by Robert Bicking, W9RB and Lowfer RB on May 13, 2002 at 21:32:28
Being an optimist, I started building a 400 W LF transmitter a while back, based on a design in the RSGB handbook. I included a provision to operate on both 160-190 and 137 kHz (looks like I don't need this). Now that it looks like we are "FER SURE" going to get priveleges at LF, I'm going to pick up speed in completing it. P. S., I have enjoyed operating under part 15 but have learned thru experience how marginal the propogation usually is and will enjoy putting out a few more mW.
Manual for VLF-354
Posted by FRank Carson on May 14, 2002 at 14:02:46
I was recently given a working Communications Electronics Inc Model VLF-354 receiver. Does anyone have one of these, have experiance with them, or have a manual? Any information would be appreciated!
Frank Carson N3OCW
WA and VD copy in Maryland
Posted by lloyd chastant on May 14, 2002 at 22:51:35
Very nice captures on VD and WA here tonite in Maryland..
de Lloyd W3NF FM19MH
Some beacons of interest
Posted by Robert Wilson on May 15, 2002 at 01:24:55
A few years ago I put up three low and medium frequency stations in the arctic. These are still operating.
I would be very interested to know if anyone can hear them.
1. NDB, call "OSE", 251 kHz, antenna 140 ft high with long top loading wires, power now 1000 W, but 4000 W available.
(Due to corona power had to be backed off to 1 KW.) N60 56.81 x W155 33.44, arctic area, Bethel, Alaska, US.
2. NDB, call "SIT", 358 kHz, antenna 100 ft high with 900 ft top loading wires, 400 W., Biorka, Alaska, US, island location,
excellent ground system, power 400 W, N56 51.28 x W135 32.06, half way between Anchorage, Alaska and
Seattle, Washington, US. Designed to cover that area but power reduced from 1 KW to 400 W due to lack of Xmtrs.
3. NDB, call " VTR", 350 kHz, antenna 100 ft high with 900 ft top loading wires, 500 W., McGrath, Alaska, US, on Yukon River.
N62 56.81 x W155 33.44. Designed to cover central Alaska. (Permafrost area, poor grounds.)
Wanted! A good software for Morse Coding and Decoding
Posted by Harald on May 15, 2002 at 05:08:53
Can you tell me the name and if available on the internet the URL of softwares for Morse Coding and Decoding.
The software should be able to work with input signals with frequencies up to 24 kHz, i.e. it should be able to process signals of VLF transmitters directly.
Further it should offer the possibility to set the frequency of the incoming morse signals in the whole frequency range between 0 Hertz and 24 kilohertz.
Which software meets these requirements best?
FCC NPRM
Posted by Lyle Koehler on May 15, 2002 at 16:02:46
Breaking news from today's FCC Daily Digest: AMENDMENT OF PARTS 2 AND 97 OF THE COMMISSION'S AMATEUR RADIO SERVICE RULES.
Addressed three Petitions for Rulemaking filed by the American Radio Relay League, Inc. requesting allocations for the amateur service in the 135.7-137.8 kHz, 160-190 kHz, 5250-5400 kHz, and 2400-2402 MHz bands. (Dkt No. 02-98).
Action by: the Commission.
Adopted: 05/02/2002 by NPRM. (FCC No. 02-136).
http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-02-136A1.doc
http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-02-136A1.pdf
http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-02-136A1.txt
Lyle, K0LR
LOWfer Speaker?
Posted by Rich Stiebel on May 15, 2002 at 17:38:33
Our radio club is looking for someone knowledgeable in Lowfering as a speaker for a meeting later this year.
If you know anyone in the San Francisco (CA) Bay Area who is into Lowfering who might be willing to give a talk on longwave communications & beacons, please let me know.
I found a website that lists beacons such as: KLFB 164.900 kHz in Sunnyvale, CA.. If you know how to contact the operator of this beacon, please let me know.
Especially with the new FCC proposed 136 kHz ham band, our ARRL affiliated club would welcome learning about Lowfering.
Please let me know if you have any leads.
Thanks,
de Rich, W6APZ Reply to: w6apz@arrl.net
TAG Back on 185.302
Posted by John Andrews on May 15, 2002 at 20:27:04
TAG is back on 185.302, QRSS30 mode. Will be on through Memorial weekend.
John Andrews, W1TAG TAG Status: http://webpages.charter.net/w1tag/
Re: Inductive "assist" loop antenna for WWVB radio clocks?
Posted by John Davis on May 16, 2002 at 10:45:01
::When you said that you coupled the long wire to the clock's own loop with a single turn, did you physically wind it around the little loopstick inside the clock or did you make a larger loop that you placed near the clock?::
We made a loop about 2" in diameter and set the loopstick antenna of the clock inside that. (Now that I think about it further, it was probably a couple of turns.)
::Either way, my coax long wire antenna should work fine for home use. The outer braid might even shield the inner conductor from the local AM signals so that the clock's receiver could more easily "hear" WWVB::
Depends. What we did was tie the longwire to the center conductor of our coax and grounded the shield outside the building. If you use your coax itself as the antenna, however, you may have to treat the braid as the signal source.
John
Top end-of -season Lowfer veiwing on a screen near you!
Posted by Bill Ashlock on May 16, 2002 at 23:28:02
For two weeks only the three loop musketeers will be featuring a spectacular season finale on 185.300, 185.301, and 185.302 in QRSS30. All those returning screen captures will receive personally signed photos of Jay, John, and yours truly, in front of our giant loop antennas. Be the first in your area of the country to display this prized possession! Never received a signal from a loop antenna?? This could be a once in a lifetime opportunity to view not one, not two, but three loop signals all on the same screen!
Send all captures to: Ashlockw@hotmail.com
(Offer good only to viewers in the USA and Canada. Members of the immediate musketeer families not eligible)
Good Luck!
Re: Top end-of -season Lowfer viewing on a screen near you!
Posted by John Davis on May 16, 2002 at 23:58:36
Bill,
If we snag an especially good capture, could we have a QSL *without* the photos? :-)
Just kidding, of course. Sounds like a grand way to cap off the season!
Good luck to all.
John D.
Re: An unidentified transmitter on 22.3 kHz received on April 2nd
Posted by Harald on May 17, 2002 at 07:23:25
Interestingly I received last year on August 5th, a transmitter on 21.7 kHz with a transmission signal typically for Russian VLF transmitters. The sampling rate I used was 22.05 kHz. Was it perhaps the same transmitter which came through on 21.7 kHz ( 22.3 kHz - 22.05 kHz = 0.25 kHz 22.05 kHz - 0.25 kHz = 21.8 kHz)?
Re: Inductive "assist" loop antenna for WWVB radio clocks?
Posted by J. Jason Wentworth on May 17, 2002 at 19:01:32
John, thank you for adding this clarification. I tested the coax long wire antenna using both the braid and the center conductor (by themselves and connected together), and the AM & SW reception on several radios was the same in all three cases. The braid and the center conductor may be shorted together at the utility pole, where they're disconnected from the cable television connector.
I think any reasonably well-made WWVB-controlled clock would be able to pick up WWVB from the coax and reject the local AM signals. For very small clocks, I could make a two-turn coil 'sleeve' (lined with paper) which would slide over the clock case. -- Jason
Re: Top end-of -season Lowfer veiwing on a screen near you!
Posted by John Andrews, W1TAG on May 17, 2002 at 19:20:28
I personally promise to be half-looped when the picture is taken.
John Andrews
Re: Wanted! A good software for Morse Coding and Decoding
Posted by george on May 18, 2002 at 17:02:51
I do not think you will be able to find ANY such software, here or on the net or otherwise, for morse decoding on VLF or LF. (In other words, you need to make one for yourself.) I think this is a FAQ but i'll try to answer.
There are two problems i can think of:
i) First for regular decoding the morse decoders on the market are pretty bad even for regular HF use. there is a WUN/Numbers and Oddities 5+ yr old article about trying to use morse decoders to gleem spy number stations that use morse code ("cut" stations). conclusion: total failure.
(aside: to solve this i think the morse decoders have to use real fancy techniques that the PhDs at, say, DragonDictate use to understand speech.)
ii) Second, there is no way any decoder is going to be able to understand VLF/ULF/LF morse unless it is specifically designed with the noise conditions in this band in mind.
But I think there is hope. witness two things: 1) slow speed morse is so totally different to decode than fast morse - fast morse seems to me to be more like speech (viz. this is why i mentioned the dragondictate thing above) - slow morse is more precise/robotic. 2) spectrogram gives you a very nice representation of the signal. Put these two facts together and you might have a way to decode morse code for vlf or lf.
YOU need to get spectrogram to save a file periodically and then write some code to scan the image. The code goes line by line thru the image looking for dah dit stuff. if it finds a relatvely long sustain streak its dah or dit depending. It's not hard to do.
it would be a nice contribution to the lf community if someone put this together.
-george
If you e-mail a reply directly to the sender of this message, removing the antispam prefix in front of his username in the To: box of your e-mail client before sending.
Re: GWEN Recordings
Posted by John Davis on May 19, 2002 at 02:44:38
Though not the sort of early historical tests Les is especially looking for, we do have a sample of the operational version of GWEN in the LWCA file libraries, along with a few other current and former denizens of longwave. Visit:
http://lwca.org/library/sound/index.htm
And if you have any interesting recordings of your own that you'd be willing to share with the longwave community, we'd be delighted to hear about them.
73 John
Re: Top end-of -season Lowfer veiwing on a screen near you!
Posted by Bill Ashlock on May 19, 2002 at 13:28:35
Hey you guys!
We are not exactly getting flooded with screen captures of the the Three Musketeers. I realize that there has been a lot of storm activity lately, in fact the ground was white yesterday (3" just to the north), so this could account for the lack of response.
To get a better idea of the propagation conditions this time of the year, we would appreciate hearing from any and all that have have been looking but have not yet made a score.
Many thanks,
Bill WA (for TAG, and VD as well)
185.300
185.3 trio
Posted by lloyd chastant on May 20, 2002 at 07:44:55
Overnite captures show nice signals on WA and VD with fading in and out and maybe?
a light trace of TAG here in Maryland de Lloyd W3NF FM19MH
1750M Counter-Proposal?
Posted by John Andrews on May 20, 2002 at 15:49:42
In the FCC's NPRM for the new amateur allocations, they invited comments on their exclusion of an amateur allocation at 160-190 kHz. I'm wondering how they would react to the following items in a counter-proposal:
1. Leave the 160-190 kHz Part 15 rules exactly as-is.
2. Add a secondary Amateur allocation at 160-190 kHz. The rules would NOT bethe same as proposed for 136 kHz, though:
A. No specification of antenna type or dimensions. Obviously, this would allow considerably more experimentation than the Part 15 rules, and would permit use of the same (larger) antennas on 136 and 160-190 kHz.
B. No reference to the transmission line. This relieves the need to keep the PA at the antenna base.
C. Transmitter power OUTPUT limited to 1 watt PEP only. This is 20 dB lower than the power level proposed for 136 kHz, and in line with the current Part 15 rules. But it would permit us to use linear PA's without being penalized for their lower efficiency.
D. Emission BW should be confined to the 160-190 kHz band, but there would appear to be no need to preclude any reasonable mode.
This would allow continuation of present Part 15 operations, and the overlay of Amateur operation with improved antennas and more transmitter flexibility. Since most of us can gain only so many dB within the bounds of our real estate, I doubt that the Amateur signals could be so dominant as to foul things up too badly for the unlicensed guys.
I'd be curious to hear comments, pro and con, with any additions or deletions. Also, thoughts on even turning this rock over would be appreciated.
John Andrews, W1TAG
Re: 185.3 trio
Posted by Bill Ashock on May 20, 2002 at 15:54:29
Nice going Lloyd!
The temperatures in this area are dipping to the freezing point over-night so this could have something to do with this success. I see that Mitch P. has some excellent captures as well.
Thanks...... will be working on those new QSLs ASAP!
Bill and the gang at 185.30x
Re: 1750M Counter-Proposal?
Posted by John Davis on May 20, 2002 at 16:30:11
W1TAG writes:
::In the FCC's NPRM for the new amateur allocations, they invited comments on
::their exclusion of an amateur allocation at 160-190 kHz. I'm wondering how
::they would react to the following items in a counter-proposal:
:: {snip}
:: Also, thoughts on even turning this rock over would be
::appreciated.
I think the last point is the biggest question. Many of you know me to be very cautious and not inclined to be too optimistic about the FCC's decision making. My track record of predicting rulemaking outcomes is pretty good when I lean slightly toward the pessimistic side. So it's only natural for me to urge caution in proposing something this specific which is also quite different from what is currently under consideration.
If you'll forgive a bit of analytical thinking-out-loud, here's how I see the downside and the upside of counterproposing.
Downside: The Commission's focus right now is whether to do anything about it at all, not exactly what to do. Their present thinking is colored by the proposal already on the table. In such instances, counterproposals are sometimes seen as muddying the waters; and when the rest of the actions open to them seem so clearcut, the path of least resistance is thus to ignore counterproposals. Sometimes such proposals are revisited later; but other times the mere fact that one is presented seems to prejudice its future consideration.
Also we should note that they asked only rather _generally_ for comments on the tentative decision not to do 1750 meters. They did ask rather _specifically_ for comments on feasibility of making the utilities' PLC database readily available and if it would reduce interference potential. Those two facts, in light of all the emphasis they placed on the utilities' arguments, give us an important clue of where their thought processes are right now.
Upside: The phrasing and tone of the requests for comments was a little more open-minded than usual. And to be perfectly candid, I think John A. has come up with a really great idea that deserves serious consideration.
My Tentative Conclusion: We don't want to bombard the Commission with multiple variations of something they've tentatively decided is off the table, and would probably be postponed to some later rulemaking at best if there were a flurry of counterproposals. BUT, if John A.'s proposal is presented in the proper light as a way around the most serious objections, which would allow real-world amateur operation as part of an interim step toward future consideration of a more normalized 1750 meter ham band, then it MIGHT not only stand a chance, but actually speed up the process.
Personally, I also think it's the best solution anyone has come up with for the multiple problems of keeping the utilities happy (in their unallocated but still highly protected status), and at the same time providing some serious accomodation for the non-ham LowFER experimenters.
I do have a few observations on some specifics of the idea. From the beginning:
::1. Leave the 160-190 kHz Part 15 rules exactly as-is.
I don't think this is in doubt. Even the ARRL was willing to leave our Part 15 status alone, although with 2W ERP, that could become something of a moot point.
::2. Add a secondary Amateur allocation at 160-190 kHz. The rules would NOT be
::the same as proposed for 136 kHz, though:
::A. No specification of antenna type or dimensions. {snip}
::B. No reference to the transmission line. This relieves the need to keep the
::PA at the antenna base.
Actually, I would note that these two items are the _same_ as the 136 kHz proposal, and differ only from Part 15. The reasons John cites for lifting these restrictions are very good points, and I endorse them heartily!
Although as Bill A. notes, some folks may _want_ to get carried away with antennas, I don't think we need to set any kind of restrictions beyond those already in place on hams re: FAA requirements. Those height limits are serious enough impediments, and length is not a particularly good substitute in LF transmitting antennas. Between the FAA and what we can realistically afford, I believe it'll be a non-problem.
::C. Transmitter power OUTPUT limited to 1 watt PEP only. This is 20 dB lower
::than the power level proposed for 136 kHz, and in line with the current Part
::15 rules. But it would permit us to use linear PA's without being penalized
::for their lower efficiency.
Excellent points also. But I believe I would sell this power level as being a way around the PLC problem, too. I seem to recall the utilities claimed one or two of ARRL's interference calculations were off by about this amount. OK, for the interim, we give away 20 db...and everybody's happy. (See, I can be an optimist at times!)
::D. Emission BW should be confined to the 160-190 kHz band, but there would
::appear to be no need to preclude any reasonable mode.
Overall, I agree. I don't even see a need for the 100 Hz bandwidth restriction at 136 kHz, for that matter.
I would offer one suggestion on this one, though: What if we confined digital modes to the lower 15 or 20 kHz of the band and allowed _only_ phone in the top segment? This would be another way of making life a little easier for the pure-Part 15 operations, who (a) have naturally congregated in the top part of the band since the GWEN days anyhow, and (b) would have a lot less trouble getting narrowband modes through a bit of SSB from time to time, and would be less likely to interfere with voice than with other digital signals.
I really like the way John presents this objective:
>This would allow continuation of present Part 15 operations, and the overlay
>of Amateur operation with improved antennas and more transmitter
>flexibility. Since most of us can gain only so many dB within the bounds of
>our real estate, I doubt that the Amateur signals could be so dominant as to
>foul things up too badly for the unlicensed guys.
It's up to each individual's conscience as to whether or how they choose to comment on it. Still, this proposal looks like a potential winner to me.
John D.
Re: Top end-of -season Lowfer veiwing on a screen near you!
Posted by John Davis on May 20, 2002 at 16:35:37
Wonder if it might be possible to extend this offer (or at least, the operation itself) a week or so into June? That would give some of the less "wired" members a chance to read about it in The LOWDOWN and get a chance to view the trio also.
73 John
PBJ back on air with borrowed antenna
Posted by Chris Waldrup on May 20, 2002 at 20:40:22
Since my antenna blew down in a storm last week for the Hifer PBJ, I have not had a chance to repair it. A friend has allowed me use of his antenna. We have it pointed at Europe right now, so any reception reports would be greatly appreciated.
Frequency is 13.55787 Mhz and QRSS6.
Chris KD4PBJ Apex, NC Wake County
Re: Top end-of -season Lowfer veiwing on a screen near you!
Posted by Bill Ashlock on May 20, 2002 at 23:16:50
The request for extension of the offer is granted. At least WA will continue sending throughout the summer unless the need to test additional loop conductors should diminish, and that's not likely to happen. I will encourage the other loop Musketeers to follow suit (and we may pick up some more). What's say WE and VLF?
Bill A
Re: 1750M Counter-Proposal?
Posted by Bill Ashlock on May 21, 2002 at 03:35:42
John,
"Although as Bill A. notes, some folks may _want_ to get carried away with antennas, I don't think we need to set any kind of restrictions beyond those already in place on hams re: FAA requirements. Those height limits are serious enough impediments, and **length is not a particularly good substitute in LF transmitting antennas**. Between the FAA and what we can realistically afford, I believe it'll be a non-problem."
I don't think you have considered the possible radiated power of a large loop at 1750m. Just on my not-so-big residential property I can increase my existing radiation from the 50'/50' loop to +9db by stretching the horizontal dimension to 9X (and have already accomplished +9db at much reduced power - shhh). "length" IS just as important as height for a loop because it is total area that counts. My calculations indicate it is easy to reach +20db with many wooded properties in this region having 100ft tall trees or just a very wide lot.
Bill A
Re: 1750M Counter-Proposal?
Posted by John Davis on May 21, 2002 at 14:20:13
Bill A. writes...
:: I don't think you have considered the possible radiated power of a large loop at 1750m. Just on my not-so-big residential property I can increase my existing radiation from the 50'/50' loop to +9db by stretching the horizontal dimension to 9X .... My calculations indicate it is easy to reach +20db with many wooded properties in this region having 100ft tall trees or just a very wide lot. ::
Certainly true, but consider where we're starting from. A 20 db improvement over even a decent LowFER antenna still leaves us a long way from obtaining 1 Watt EIRP out of a 1 Watt TPO.
If you have either a 100 foot high loop several hundred feet long, or a single vertical 200 feet high with extensive loading (and away from lossy objects), the efficiency is still only somewhere on the order of 1%. So we're still 20 db below 1 W ERP at that point, and almost 18 db below the Dreaded Full Watt EIRP that so frightens the power companies.
If one goes to such a length-- literally or figuratively-- and even if he somehow merits an SLF of +6 db on top of that ("Sheer Luck Factor"), that'd still be only 40 mW or so of radiated power. But I'm very doubtful that the Capricious Spirits of Radio will bless very many folks, if any, with such favor.
Such a signal would stand out prominently over the microwatts a pure-Part 15 station radiates, yet I'd still rather be competing against milliwatts than full watts. :-)
John D.
PBJ heard in Belgium last night
Posted by Chris Waldrup on May 22, 2002 at 07:32:37
I just got a confirmed report from Johan Smet that he copied PBJ in Belgium last night. He could hear no audio but captured a weak signal with his computer.
Chris Waldrup Apex, NC
185.3 copy in Maryland
Posted by lloyd chastant on May 22, 2002 at 08:06:55
The captures last nite continue to be as good as the winter season.Captured all three-TAG,WA,VD during overnite with WA and VD continuing to be very big at times..de Lloyd W3NF FM19MH
Re: PBJ back on air with borrowed antenna
Posted by Tim Brannon on May 23, 2002 at 02:08:37
"We have it pointed at Europe right now..."
Assuming this means that the antenna has some gain relative to a 1/4 wave vertical, how did you adjust your transmitter power output to stay within the field strength limits?
Re: PBJ back on air with borrowed antenna
Posted by Chris Waldrup on May 23, 2002 at 07:20:26
I used an attenuator in the transmission line.
Chris
^Inverted Coathanger^ Long Wave loop antennas?
Posted by J. Jason Wentworth on May 24, 2002 at 04:25:30
Hello All,
I have been reading Sheldon Remington's excellent online book, ^On The Art of NDB DXing^. In Chapter 11 (^Visiting Beacon Sites^), he includes illustrations of the various marine and aeronautical Non-Directional Beacon antennas.
Two rather unusual Long Wave aeronautical NDB antennas he illustrated are the 3-point and 5-point "Inverted Coathanger" loop antennas. They look somewhat like HF triangular loop antennas, but these NDB loops are fed with only a single wire from the transmitter.
Would these antennas work well for Long Wave reception? (They have more wire ^in the air^ than a T-antenna of comparable size, and their lower feed points might make them easier to erect.) If so, are there any rules of thumb for the antenna dimensions and mounting height?
Many thanks in advance to anyone who can help. -- J. Jason Wentworth
Inexpensive LF & VLF loop antennas source (link)
Posted by J. Jason Wentworth on May 24, 2002 at 04:42:49
Hello All,
You have been very helpful to my efforts to get into LF DXing and (eventually) LF broadcasting, and I would like to return the favor.
I recently found a small firm that makes small tunable circular loop antennas. Ed Wawzinski is the President of EDEK ELECTRONICS (622 DEER PARK AVE., OAKLAND, MD 21550, Tel: 301-334-5228). His firm produces inductively-coupled and hard-wired loop antennas for VLF, LF, MW (AM), and SW. He will make loop antennas to custom specifications, and he is currently working on a 60 kHz WWVB ^assist^ loop antenna to enable atomic clocks & atomic watches to receive WWVB strongly in Alaska and Hawaii.
I hope this information will be helpful. -- Jason
Re: ^Inverted Coathanger^ Long Wave loop antennas?
Posted by Jonathan Smick W2MXW on May 25, 2002 at 01:18:07
Wow, been awhile since I've poked around in this here board :-) Glad to see interest in LF broadcasting is alive and well (saw yours and Will's posts further down). Good luck in your efforts. I am constructing my LF station now, decided to go with an all-tube TX, finally getting to it after gosh-knows how long.
Anyway, that's O.T. for this post. The type of antenna you describe is simply a variant on the "T" and not a true loop as the single downlead (which is in actuality the radiator, as it is on a conventional "T") is directly connected to the overhead "loop" wires which in turn are all tied (or simply made from a single closed loop of wire) to form essentially a topload or capacity hat system (and don't radiate). A true loop would use either coax or multiconductor cable, or a coil wound on a "spider" frame, usually shielded (in the case of a coax single-turn job, the braid is the shield) and would in any case have a coax or other two-conductor transmission line feed. Often there are two loops in a true loop, one is the main antenna (larger and/or with more turns) and one which is smaller and/or has fewer turns which is placed next to or inside of, and inductively coupled to, the main loop and not directly connected. This smaller coupling loop connects to the feedline (or a tuner and then feedline). The main loop is usually also independently tuned with a capacitor. Loops are not to be recommended for Part 15 transmission (but great for RX, I swear by them for the latter) as you would need a *really* liberal interpretation of the rules to make a reasonably efficient one within the 15 meter limit.
As far as coathanger antennas, it may be a little harder to construct one than a conventional "T" as you may need more wire, and for some designs more support points but, on the plus side you may get more capacitance than a typical "T" has (except perhaps the 3-parallel type).
I'm working on a "T" for my soon-to-be LF operation. I scrapped the original vert. monopole I was planning in favor of the "T" as the latter, which will have about 30 feet in the top (overhead span) section, has much more capacitance than I could muster from an 8' diam. top hat on a pole, thus will be more efficient.
Jon
Re: ^Inverted Coathanger^ Long Wave loop antennas?
Posted by J. Jason Wentworth on May 25, 2002 at 02:15:07
Jonathan, thank you for the information. It makes sense, but it also leaves me a bit puzzled. The drawings of the 3-point and 5-point "Inverted Coathanger" antennas show that they have *very* short vertical downleads as compared to the vertical downlead on a Marconi "T" antenna.
Is it possible that the wires sloping down to the vertical downlead *do* radiate as well, or do they just use a bigger loading coil to compensate for the short vertical downlead? If the sloping wires do radiate, then the "coathanger" antennas might have a combination of vertical and horizontal polarization, which would be good for DXing distant Long Wave stations coming in via skywave with "scrambled" polarization. -- Jason
ZL6QH tests 22 June
Posted by Bob Vernall on May 25, 2002 at 20:20:07
Hi all,
ZL6QH is intending to transmit LF beacon signals on Saturday 22 June. It is likely that the beacon will use the same narrow FSK and 120 second dot length beacon format as for previous tests, on a selected frequency near 137 kHz. Details will be posted nearer the time.
73, Bob ZL2CA
Re: ^Inverted Coathanger^ Long Wave loop antennas?
Posted by John Davis on May 25, 2002 at 20:55:17
:: The drawings of the 3-point and 5-point "Inverted Coathanger" antennas show that they have *very* short vertical downleads as compared to the vertical downlead on a Marconi "T" antenna. ::
This is largely a mechanical convenience (consider the downward stress on the horizontal run of a conventional tee), although one of the consequences is that it helps to increase the capacitance of the antenna, as Jonathan notes.
:: Is it possible that the wires sloping down to the vertical downlead *do* radiate as well, or do they just use a bigger loading coil to compensate for the short vertical downlead? ::
They do radiate, and because of the greater capacitance, it's actually a somewhat smaller loading coil. With a capacitive top load, the coil resonates the whole capacitance of the antenna anyway, not just the vertical run.
:: If the sloping wires do radiate, then the "coathanger" antennas might have a combination of vertical and horizontal polarization, which would be good for DXing distant Long Wave stations coming in via skywave with "scrambled" polarization. ::
Not significantly. You can plot the current flow at any given point in each wire as a horizontal component and a vertical component. If you look at it this way, both wires will have y-axis vectors with an upward direction. But the left wire will have a leftward horizontal vector, while the right wire will have one of equal magnitude to the right. The horizontal components cancel, just as they do in a regular tee, and there is only the net vertical component.
John
Re: ^Inverted Coathanger^ Long Wave loop antennas?
Posted by Jonathan Smick W2MXW on May 26, 2002 at 23:09:12
Yes, the "quasi-vertical" portions of a coathanger do radiate as well. I apologize for not having been more clear - what I should've said was "the typical capacity hat system doesn't radiate" or more properly "doesn't radiate much of anything useful" :-) rather than implying the whole topload of a coathanger doesn't. My mistake. But in any case the coathanger isn't typical. The horizontal top wire would be more a nonradiating element. The vertically polarized radiation contribution by the "V" portion would be most useful. H-pol is pretty much useless at low and medium frequencies, as the E-field of such is short circuited in the earth, even if there were a significant H-pol component. And as John says, any horizontal component produced by the legs of the "V" is largely cancelled out.
There is a blurring of distinctness with respect to what is more the "radiator" and what functions more as the "capacity" element in the coathanger configuration (except perhaps with respect to the totally horizontal top span) as compared with a more conventional "T", and all the elements contribute some of both capacitance and radiation. The horizontal top span would have the least useful radiation component and the greatest influence on system capacitance. But suffice it to say any portion that is *reasonably* vertical contributes more to useful radiation and anything more in the horizontal realm, more to system capacitance.
Since the "V" in a coathanger is both part vertical downlead and partly horizontal, it muddies the issue somewhat.
As you can see there are many ways to skin the proverbial, er, cat, or permutations of Marconi type antennas.
We can have types which are almost all "capacity hat" or where there is less distinction between "radiator" and "hat". Anything with more wire in the air, especially if much of that wire is in a generally more horizontal plane, as John says would most likely actually use *less* loading coil inductance to resonate due to the increased capacitance. The length of the truly vertical downlead makes less difference than might be expected in that regard; if anything, the shorter it is the less inductance is needed in the coil because the elements are closer to ground giving greater capacity. They are closer to the coil, too, and this can be bad if there is too much distributed capacity to the coil. Thus a reasonable length vertical downlead is better engineering than a really short one.
As far as DXing goes, I would venture to guess that the majority of Lowfers use a loop of some sort (myself included) or, for those lucky few having the real estate, perhaps a Beverage.
73, Jon
Re: ^Inverted Coathanger^ Long Wave loop antennas?
Posted by J. Jason Wentworth on May 27, 2002 at 09:29:15
Thank you all very much for clarifying these antennas' characteristics for me. I'm looking for a physically robust LW antenna that can withstand wind and ice coatings, and the 3-point and 5-point "Inverted Coathanger" antennas sound like good choices.
Are there any "rules of thumb" for these antennas' dimensions, or are they usually built "to fit" the available space and then tuned to resonance? -- Jason
185.3 May 30
Posted by lloyd chastant on May 30, 2002 at 08:13:55
I did some overnite captures during the last two nites and saw virtually nothing on the May 29 but did have some WA VD come through during the 1 AM to 3 AM local time.Weather has been warming up quite a bit..de Lloyd W3NF
Re: AIR MILE CALCULATOR
Posted by Ellis on May 30, 2002 at 10:41:35
Les, found site to be very useful, put in my favs,for future ref,will use a lot! Tnx. de Ellis Wa1rks.
LF Ham Band
Posted by Robert Bicking, W9RB on May 31, 2002 at 19:43:21
Having just received the latest Lowdown, I would suggest that a vote of the LWCA members be taken on e-mail (and regular mail for those that don't have e-mail) on the proposals for a LF ham band and that the results be forwarded to the FCC. The options could be listed on the LWCA web site.
My personal feeling is that if we get SOMETHING it will be a start and we can argue for further priveleges later. The arguments about interference will only be settled by data.
www.lwca.org
potrzebie