Re: Frequency of NAA Circa 1961?
John W1TAG and John D,
Lots of Johns here. John W1TAG, I would like to acknowledge your SX 101. We all saw the adds in QST and CQ in those days, but the first SX 101 that I saw in person was at the State Fair of Texas on "ham" day at the fair in October 1957. It was the grand prize for the lucky winner of the drawing. I came home empty handed of course.
In '58 when I built my first SSB rig, I borrowed a Heath audio oscillator and 'scope from a fellow ham here in town.
He had an SX 101 and HT 32 combo. What a cool looking set up! (and a lot of money in those days).
When I returned the equipment to him a week or so later, I was shocked to see that he had traded in the SX 101 for a Drake 1A receiver.
His HT 32 looked absolutely heart broken sitting next to that little Drake 1A.
Beyond my early days of LF/VLF tinkering, I never did much. My first interest began about 1953/54 when I built crystal sets for the old 200/400 kc aircraft beacon band. Had to wait until after sign off at night of the local clear channel 50 kw BC station on 820 kc to hear any local beacons.
Does anyone recall NAA's power in the Sixties? Seems like I read somewhere that they ran 2 megawatts by using four 500 kw Continental Electronics transmitters coupled together.
John
Re: Frequency of NAA Circa 1961?
Posted by Trond Jacobsen on March 01, 2006 at 08:08:13.
In reply to Frequency of NAA Circa 1961? posted by Litzendraht on February 26, 2006
Hello John
As far as I can figure out from the notes in my archive was NAA Cutler using 14.7 kHz in the "60's", was using 17.8 kHz in '79, then moved to current 24.0kHz. Several other frequencies been used ( and listed ) a well. Guess they still has operational capabilities for other frequencies then 24 kHz too. ( There is a public / non classified Spawar pdf document where you can read of the top hat arrangement of NAA, this doc list two other frequencies as well as the current 24.0 kHz, downloadable from the Spawar site )
Best regards
Trond Jacobsen Re: ID?
Posted by Warren K2ORS/WD2XGJ on March 01, 2006 at 13:36:35.
In reply to Re: ID? posted by Alan G3NYK on February 28, 2006
The programmer of the i.d. got drunk and tried to program "En Vino Verite", the result is what you hear... LF Ant Mutual Coupling
Posted by Peter B on March 02, 2006 at 18:19:53.
Fellows,
Thought I'd pass this observation along. I noticed that a multi-turn 5-foot loop ant. can nicely couple into that of a nearby vertical for 137KHz rx. The loop, when resonated to the Vert freq, appeared to perform surprisingly well given its size--actually equal to the bigger Vert. Then for another reason I repositioned it, say, 15-feet away, and found it unexpectedly quiet. I checked the feed line, etc., nothing amiss, then the proximity thing came to me. That was it, I found on replacement. But I didn't expect the degree of coupling given the loop and Vert were cross polarized, but it did. Ha, live n' learn.
Peter
Re: LF Ant Mutual Coupling
Posted by John Litzendraht on March 03, 2006 at 01:40:51.
In reply to LF Ant Mutual Coupling posted by Peter B on March 02, 2006
Peter,
Folks that are experimenting with new antennas often overlook the proximity to exsisting arrays.
It sure threw me off track when I was tinkering with small HF loops 40 years ago. (I was in close proximity to my full length station antenna).
But you are correct! Live and learn.
John Re: 454 kHz MD Heard in GA Day and Night
Posted by Steve Ratzlaff AA7U on March 03, 2006 at 03:46:58.
In reply to 454 kHz MD Heard in GA Day and Night posted by Brock Whaley on February 18, 2006
I've been wondering what this signal is--very strong in NE Oregon, any night. Re: Height diagrams...
Posted by Webmaster on March 03, 2006 at 14:21:20.
FYI: Harald has updated his graphic comparing LWBC transmitting antenna heights a couple of times since posting his original message. It's under the same filename, so if you'd like to have the updated version, the link in Message 4791 still works to obtain the new image.
John
Re: LF Ant Mutual Coupling
Posted by Alan G3NYK on March 04, 2006 at 10:12:50.
In reply to Re: LF Ant Mutual Coupling posted by John Litzendraht on March 03, 2006
Hi yes think of the current flowing down the vertical and into the ground as part of a loop with a big capacitor completing it. Try the experment again but detune the vertical and you will find the interaction disappears. Its a bit like the "GDO Effect" where a resonant circuit "sucks" power from a source. Finbar and I actually measured it on one of our experiments
see www.alan.melia.btinternet.co.uk/aecouple.htm
Don't forget the size of the near-field region at LF is massive compared with HF.
Great Fun antennas
Cheers de Alan G3NYK
Re: ID?
Posted by Michael Oexner on March 04, 2006 at 10:29:27.
In reply to ID? posted by Bob on February 27, 2006
Hi Bob,
Your were listening to negative keying orginating from BKL-416 Cleveland/Burke Lakefront in Ohio.
vy 73 + gd DX,
Michael
lowfer 172,800 hertz--sf bay area, calif
Posted by Steven Bjork on March 06, 2006 at 00:30:03.
Hi Folks--lowfer fever struck here, and I've been dabbling with Lyle's
downconverter and transmitter, with glfer (under linux). I've thrown a
wire out the window and am transmitting on 172,800 hertz. My receiver
only has a random wire for antenna at the moment. I'm mulling over my antenna
choices but currently am leaning towards a differential amplified vertical.
So far I pick up my own xmitter (cough) and a lot of computer room hash.
Ok back to the soldering iron and google searching. Appreciate any comments
or reception reports. ../Steven
Re: lowfer 172,800 hertz--sf bay area, calif
Posted by Webmaster on March 06, 2006 at 02:23:53.
In reply to lowfer 172,800 hertz--sf bay area, calif posted by Steven Bjork on March 06, 2006
Hi Steven,
So that we can get you in the beacon lists:
*what are you using for a callsign?
*which community are you in, or located nearest to?
*what speed are you using for transmission?
*what sort of hours do you operate?
Thanks.
John
Re: Message Board Progress and Survey
Posted by Webmaster on March 06, 2006 at 02:35:45.
In reply to Message Board Progress and Survey posted by Webmaster on February 22, 2006
We had several responses to the survey question, which I have now removed for sake of conserving space. The general consensus seems to be that we don't need to have sub-forums for specialized areas of the hobby at this time.
Based on your feedback, we'll leave the Board much as it is now for the foreseeable future.
Thanks for all your comments, and feel free to offer additional suggestions at any time.
John
details, was Re: lowfer 172,800 hertz--sf bay area, calif
Posted by Steven Bjork on March 06, 2006 at 16:46:06.
In reply to Re: lowfer 172,800 hertz--sf bay area, calif posted by Webmaster on March 06, 2006
Details--call is SWB. Location is El Sobrante (94803), Calif.
Speed/mode is qrss at 2.4 wpm, settable in the glfer app.
Lately I've been running in afternoon/evening PST hours.
Once I code/hack up an 89c2051 morse keyer, likely I'll
keep the beacon up 24hrs. ../Steven
LowFER LEK not operational
Posted by Lyle Koehler on March 06, 2006 at 17:24:31.
I apologize for not updating the LEK beacon status in the LowFER list. Except for a brief beacon transmission and a QSO with RM on New Year's Eve (using a terribly inefficient makeshift antenna), LEK has not been on the air at all this past season.
Lyle, K0LR Next Sunspot Cycle 30-50% Stronger than Last One
Posted by Warren K2ORS/WD2XGJ on March 06, 2006 at 21:08:00.
Researchers at the National Center for Atmospheric Research predict that the next sunspot cycle will be 30-50% stronger than the one just passed. The cycle is forescast to start 6-12 months later than normal, starting in late 2007 or early 2008. The peak is forecast to be in 2012. The forecast is based on a plasma model of the sun's interior. For more info:
http://www.ucar.edu/news/releases/2006/sunspot.shtml
Anyone care to speculate on the LF effects?
73 Warren K2ORS/WD2XGJ HP 3591A Selective Voltmeter as VLF receiver
Posted by Dale Powell on March 08, 2006 at 01:19:07.
Greetings from a first time poster. I am a fairly new VLF listener, and have been using a couple Kenwood HF transceivers for beacon reception.
I recently read that many lowfers are using selective voltmeters, I happen to have a very old HP 3591A with a 3594A sweeping oscillator. This unit has bandwidth settings of 10, 100, 1000, and 3100. More filters than many of the newer units. It has Nixie tube displays. Has anyone used this or a similar HP radio?
Thanks-Dale AL7Y The 411 metre mast of longwave transmitter Hellissandur
Posted by Harald on March 08, 2006 at 12:42:16.
In 1963 for LORAN-C transmissions at Gufuskálar near Hellissandur ( http://en.structurae.de/structures/data/index.cfm?ID=s0014958 ) a 411 metre tall guyed mast, which is insulated against ground, was built. This mast, which has been used since mid-ninties for longwave broadcasting of Ríkisútvarpiđ on 189 kHz is still the tallest construction in Western Europe.
The transmitter Hellissandur of Ríkisútvarpiđ may be the best receivable longwave broadcasting station at the western parts of North America, because wave propagation goes all over well conducting sea water.
Nevertheless there are still only few pictures and technical data of this transmitter available. Everyone who wants to know more about this mast should visit http://www.fishing-boating.com/vento/sandur.htm Desert Excursion
Posted by Brian Webb on March 10, 2006 at 00:33:13.
An excursion to the desert north of Ridgecrest, California is tentatively planned for Saturday, March 25. Activities will include astrophotography and the evaluation of a very long antenna.
The antenna, which will be either 1,200 or 2,400 feet in length, will be used to test its suitability for receiving shortwave time signals at very long distances. I'm an occasional VLF/LF DXer and have used very long wires in the past with very good results.
At the very least I will bring an LF-capable portable receiver and take a look at the LF beacons. If somebody shows up on March 25 with some good LF gear, I'll let them hook it up to the antenna. I may actually deploy two identical wires at right angles to one another to get directivity info.
The area in question is a 3-1/2 hour drive north of the San Fernando Valley and is far enough from Los Angeles, Lancaster, and Palmdale to almost qualify as truly dark. This makes it a good location for either visual astronomy or astrophotography.
If you're an astronomy or radio enthusiast and would like to be part of this event, please e-mail kd6nrp@earthlink.net.
Please note that the above trip is contingent upon my schedule and other issues.
Regards,
Brian Webb, KD6NRP
www.spacearchive.info
circuit boards
Posted by rb on March 10, 2006 at 13:38:49.
Looking for a built, ready made circuit board for small, solid state 100khz preamp that works on 6-15vdc. Any sources of such a board would be appreciated. Vakarel, Bulgaria, world's tallest Blaw-Knox Tower
Posted by Harald on March 10, 2006 at 15:36:25.
In 1937 at Vakarel, Bulgaria, world's tallest Böaw-Knox Tower was erected ( http://www.sofiaecho.com/article/notes-from-history-70-years-of-bulgarian-national-radio/id_10720/catid_29 . This tower, which was in 1937 with a height of 352.9 metres world's second tallest tower may be still in use for broadcasting the program of "Radio Horizont" on 261 kHz with a power of 60 kilowatts. Pictures of this tower can be found on
http://www.predavatel.com/bg/1/sof.htm#vak .
It is one of the four remaining Blaw-Knox Towers in Europe: other Blaw-Knox Towers in Europe are Lakihegy Tower at Budapest Lakihegy (year of built: 1933, height: 314 metres, http://en.structurae.de/structures/data/index.cfm?ID=s0016171 ), Radio mast Lisnargarvey at Lisnargarvey, Northern Ireland (year of built: 1936, http://en.structurae.de/structures/data/index.cfm?ID=s0016174 and http://tx.mb21.co.uk/gallery/lisnagarvey.asp ) and one radio mast of Stara Zagora transmitter ( http://www.predavatel.com/bg/4/sta.htm ). Re: circuit boards
Posted by Warren K2ORS/WD2XGJ on March 10, 2006 at 18:26:39.
In reply to circuit boards posted by rb on March 10, 2006
RB,
Not sure if this is what you are looking for but David Bowman G0MRF has some ready made 137 kHz preamps:
http://www.g0mrf.freeserve.co.uk/preamp.htm
73 Warren K2ORS/WD2XGJ Re: circuit boards
Posted by John Davis on March 10, 2006 at 20:38:02.
In reply to Re: circuit boards posted by Warren K2ORS/WD2XGJ on March 10, 2006
In addition to the preamps Warren mentioned (which are very robust units and are tunable over a modest range of frequencies), a number of kit makers such as Ramsey Electronics have broadband preamps, in case you are interested in a broader range of LF coverage.
Also, a hint when posting your e-mail address, rb: On this board, your address does not reside as plain text in the message file on the server, so it's not readily susceptible to spambots. It's encoded as HTML entities up to the moment it displays in your browser. So, there's no need to insert other stuff into the domain name as an anti-spam measure.
John
VLF Antenna
Posted by NewGuy on March 11, 2006 at 04:16:17.
HI,
I am new to all of this and was wondering if anybody could give me some pointers on building a compact antenna for use between 15KHz and 600KHz.
Any Help is most Appreciated
Thank you
Re: VLF Antenna
Posted by Warren K2ORS/WD2XGJ on March 11, 2006 at 12:14:01.
In reply to VLF Antenna posted by NewGuy on March 11, 2006
Hi,
There are a number of ways to go, depending on what you are trying to do. The smallest would be an e-probe antenna which is a short whip fed directly into a very high impedance pre-amp. You do need a quiet location for an e-probe since it is omni-directional. Another route would be a loop antenna, if you are looking for 15-600 kHz coverage then probably an untuned loop would be easiest. The loop would have deep nulls which you could use to null out noise sources. However, it wouldn't be that small. I can e-mail you a circuit for an e-probe antenna. For loops have a look at:
http://imagenisp.ca/jsm/Burhans.html
http://www.wellbrook.uk.com/products.html#ALA1530
73 Warren K2ORS/WD2XGJ
Re: VLF Antenna
Posted by NewGuy on March 11, 2006 at 16:16:55.
In reply to Re: VLF Antenna posted by Warren K2ORS/WD2XGJ on March 11, 2006
Hi Warren
The e-probe antenna sounds like the way to go...I do live in a fairly quiet location but there is a very small power substation about a quarter of a mile from me. Do you think that is enough to make the e-probe antenna useless?
I would very much like to see circuit for an e-probe...my address is EVANS AT AOL.com
I like the idea of a loop antenna but although I have more then enough room for a bigger antenna I really would prefer a smaller size.
I also don't know enough about antennas(I just cant seem to understand them no matter how much I study them)to know what a deep null is and if it is a good thing to have? Although reading your post it sounds as if the deep nulls are a good thing especially if that substation poses a problem
I have also been looking at this antenna design.Do you think this would work for me?
http://www.vlf.it/easyloop/_easyloop.htm
I appreciate your reply Re: VLF Antenna
Posted by NewGuy on March 11, 2006 at 16:18:32.
In reply to Re: VLF Antenna posted by NewGuy on March 11, 2006
I messed up my email address...It is
Evans8119 AT aol.com
Sorry Re: VLF Antenna
Posted by Warren K2ORS/WD2XGJ on March 11, 2006 at 17:14:17.
In reply to Re: VLF Antenna posted by NewGuy on March 11, 2006
I sent you a circuit via e-mail. Re: VLF Antenna
Posted by Warren K2ORS/WD2XGJ on March 11, 2006 at 17:34:07.
In reply to Re: VLF Antenna posted by NewGuy on March 11, 2006
Hi,
I think that the easyloop will work fine but it won't give you the frequency response you are looking for. The op-amp circuit in the easyloop will limit your highest frequency to 22kHz, so the easyloop is good for 0-22kHz only.
I think the e-probe is desinitely worth a shot, also have a look at the links that I sent you earlier on loops.
73 Warren K2ORS/WD2XGJ
Re: VLF Antenna
Posted by John Davis on March 11, 2006 at 17:44:05.
In reply to Re: VLF Antenna posted by Warren K2ORS/WD2XGJ on March 11, 2006
:: ... what a deep null is and if it is a good thing to have?
A null in an antenna's pickup pattern means there is a specific direction from which the antenna is almost deaf to signals. The "deeper" the null, the more deaf it is in that direction.
In the case of a small loop, there are nulls in two directions, directly opposite each other from the plane of the loop.
If you have a noise source or interfering signal on top of the one you're trying to hear, you can manually orient the loop so that one of its nulls points toward the unwanted signal, thus hopefully leaving the desired station in the clear.
There is a potential drawback, though: the technique is only useful if the offending signal is not in the same direction as the desired signal, and also not 180° away from it. In other words, if you, the desired signal, and the interference are in any sort of straight line with each other, then nulling the noise also nulls the signal.
There is a technique for combining the output of a loop and an omnidirectional antenna so as to produce a more or less heart-shaped pattern (cardioid) with a single null in its pattern. Sometimes this makes it easier to put the noise source in the null without impacting the signal. It's a bit more complicated and may be more than you want to bother with right now. However, if you are interested in exploring the idea at some time, there are several chapters in the article On the Art of NDB DXing that deal with antennas and noise reduction techniques.
At this point, I suspect you will find the active whip antenna to be quite useful. One advantage they have is that you can move them about easily to find a location on your property where noise is at a minimum.
Good luck.
Re: VLF Antenna
Posted by NewGuy on March 12, 2006 at 02:18:45.
In reply to Re: VLF Antenna posted by NewGuy on March 11, 2006
Hi Warren,
Thank you for sending me the e-probe article. Looks like not only a fun project but just the thing I was looking for.
Which one out of the two designs do you think would be the best...the PaOrdt-mini-whip or the AMRAD Active Antenna?
I have been looking over the links that you sent earlier on loops but my attention has been drawn away from them towards the Active antenna and e-probe.
Hi John,
Wow,Thanks for such a great explanation on what a Null is.
I have so much to learn in this area its ridiculous...but I am willing to learn.
Once I get into this a bit deeper and start understanding what I am actually doing and trying to accomplish I definitely will do some experimentation with antennas and noise reduction techniques.
One thing that worry's me is that Substation but from the sounds of it I should be able to get around any noise it may generate by exploring with the active whip antenna?
I really appreciate both of your guys help and explanations.
I cant wait to start building something...that parts always fun.
Thank you Re: VLF Antenna
Posted by John Andrews, W1TAG on March 12, 2006 at 10:32:08.
In reply to Re: VLF Antenna posted by NewGuy on March 12, 2006
"Which one out of the two designs do you think would be the best...the PaOrdt-mini-whip or the AMRAD Active Antenna?"
The PA0RDT design is easy to reproduce, with readily available parts. Most who have tried it are quite impressed. It's a simple circuit, basically an FET source-follower to present a high impedance to the whip, and an emitter-follower biased at fairly high current to drive the coax line back to the receiver. It does have one shortcoming: if you are close to AM broadcast transmitter sites, you may find mixing products down in the LF range. For example, I have (among others) nearby AM stations on 580 and 830 kHz. The mini-whip amplifier dutifully produces the mixing product of 830-580 = 250 kHz. Since each of these products contains the audio sidebands of the original signals, the result can be annoying.
The AMRAD whip design is a bit more bulletproof, running a lot of current through a special FET. The circuit also has some negative feedback that improves the linearity. It is harder to build, and requires that unusual transistor. But you may have better results in a crowded RF environment.
There was an excellent-looking design by John Hoopes in the LWCA's "The Lowdown" magazine a few months ago. I'm planning to give that a try when time permits.
Here's a tip: Build the PA0RDT circuit, and see how it works for you. It's better to pick up a soldering iron than to get stuck like a deer in the headlights after over-analyzing circuit designs! <g>
John Andrews Re: VLF Antenna
Posted by NewGuy on March 12, 2006 at 16:38:42.
In reply to Re: VLF Antenna posted by John Andrews, W1TAG on March 12, 2006
Hi John,
Yeah,I was going over both of the designs and I think I will go with the PA0RDT design.
I just need to sit down and figure out the values of the parts as they aren't given in the instructions.
Then once I am comfortable with that I will try the AMRAD.
Some how I think that this is going to get real addicting real quick.
I am somewhat in the clear of any strong AM broadcast transmitters though sometimes they do come booming in.
My plan for this is to mount it on one of my towers about 2 or 3 foot from the top on a 5-6 foot boom if I can get away with it.
I still have a few more questions on building this before I start but I don't want to bother you guys with them as you have already done a lot for me.
I really appreciate everything. getting the eclipse by radio ... March 29, 2006
Thank you
Posted by Martin B. on March 13, 2006 at 06:52:13.
Dear, Re: getting the eclipse by radio ... March 29, 2006
on 29th of March 2006 we'll observe the sun eclipse with school classes, close to Vienna, Austria. In addition to the normal observation with telescopes I also want to make a nice experiment with radio waves. When the moon obstructes the sun the ionosphere should behave like during the night and reflect the radio waves. I assume when I tune a ahort wave receiver to a station in Africa during the night I will not receive the station during the day. But when the moon shadow is passing then the reflection should work again, possibly with a few mintues delay.
Can I please ask what station in Africa I should select and which frequency I should tune?
Many thanks in advance, Martin Brodicky
Posted by Alan G3NYK on March 13, 2006 at 10:36:46.
In reply to getting the eclipse by radio ... March 29, 2006 posted by Martin B. on March 13, 2006
Martin, if you are in the shadow path of the eclipse there is a slight problem. You would need to have the shadow halfway between you and a radio station so that the shadowed part of the ionosphere was the part involved in the "reflection" of the radio signal. If you are in the shadow you are really restricted to looking for a station that is also in or very close to the shadow path, either to the east or the west. If you choose a low frequency station you also need to be outside the ground-wave service area, which probably means more than 500 to 700kms distance. If you use the higher frequencies, then the ground wave is very much less, and different effects will be seen. I can not make an actual suggestion because I am not sure of the shadow's path but hopefully that will give you some ideas. If you check on Google there should still be reports from a Belgian University on experiments in 1999. I think possible John Devoldere (I hope that is the correct spelling) was involved.
Best Wishes
Alan G3NYK
Re: getting the eclipse by radio ... March 29, 2006
Posted by Martin B. on March 13, 2006 at 11:15:38.
In reply to Re: getting the eclipse by radio ... March 29, 2006 posted by Alan G3NYK on March 13, 2006
Hi Alan,
many thanks for the prompt response! The path of the eclipse starts in South America, is then over Africa, leaves Africa at Lybia, then it goes via Turkey to Russia. A simulation of the path can be seen here: http://www.waa.at/hotspots/tse20060329/tse20060329.html
I'm located very close to Vienna / Austria. So when I could find a station on the other side of the eclipse path, somewhere in Central Africa, it would be right? It's then also far away, no problem with ground waves. I hope it's not too far.
Many thanks again,
Martin
Why are Blaw-Knox radiators worse than standard guyed masts
Posted by Harald on March 13, 2006 at 11:50:51.
Why have Blaw-Knox Towers have worse radiation patterns in comparasion to standard mast radiators of the same length? Re: ID?
In which way show Blaw-Knox Radiators a worse behaviour? Has a Blaw-Knox Radiator of a given height/wavelength ratio a worse effiency or does it produce more skywaves?
Or are Blaw-Knox Towers not built any more, because they are more expansive than standard masts of the same height?
Do some radio amateurs or LOWFer freaks also use antennas of Blaw-Knox type?
Posted by bob on March 13, 2006 at 11:59:14.
In reply to ID? posted by Bob on February 27, 2006
Thanks for the info guys, unfortunately BKL is not a new one for me. GL & 73 Bob Re: Why are Blaw-Knox radiators worse than standard guyed masts
Posted by John Andrews on March 13, 2006 at 13:21:22.
In reply to Why are Blaw-Knox radiators worse than standard guyed masts posted by Harald on March 13, 2006
Harald,
There is an internet-based fascination with Blaw-Knox towers that I cannot understand. Blaw-Knox was a popular tower manufacturer from the 1930's into the 1950's. Part of the reason for their popularity was that RCA sold their products, and RCA was the dealer for many broadcast installations during that time.
Most of their towers were self-supporting, with a fairly wide base and a taper to a much smaller top section. Many of these towers were used as quarter-wave or shorter radiators, and the larger cross-section at the bottom was felt to be appropriate to the current distribution on the tower. However, when a tapered tower is used as a half-wavelength (or similar) antenna, some consideration may have to be given for the distortion in the current distribution when calculating radiation at vertical angles above horizontal.
Blaw-Knox made a relatively small number of "guyed cantilever" towers which were small at the bottom and top, and wide in the center. Guy wires were attached in the central area for mechanical stability. Such an arrangement was felt to be more appropriate for a half wavelength tower. Some towers of this design remain in use, and certain people on the Internet seem to think they are the only towers that Blaw-Knox ever built.
The question of current distribution was once a hotly-discussed subject, as many MW stations on clear channels would attempt to maximize their ground-wave coverage area for the daytime, and their non-fading zones at night. Here in the U.S., the present congestion of the AM band has rendered these concerns much less important, as coverage is generally now limited more by interference from other stations, especially at night.
Back in the 1930's, many believed that all of the guy wires involved with a multi-tower array made up of uniform cross-section towers would present a problem in establishing and maintaining pattern of the array. Experience has proven otherwise, but a lot of self-supporting towers were sold as a result.
The Blaw-Knox self-supporting towers were quite well made. There is an AM station near me that has four of the standard taper towers, 115 meters tall, and now 67 years old. They are in excellent condition. Self-supporters do have two major drawbacks: They are very expensive to paint, because of the large surface area. They also have a nasty failure mode in hurricanes, as there are no guy wires to damp the oscillation of the upper section of the tower if the wind comes in regular gusts.
John Andrews Re: getting the eclipse by radio ... March 29, 2006
Posted by John Davis on March 13, 2006 at 16:32:01.
In reply to Re: getting the eclipse by radio ... March 29, 2006 posted by Martin B. on March 13, 2006
:: So when I could find a station on the other side of the eclipse path, somewhere in Central Africa, it would be right? It's then also far away, no problem with ground waves. I hope it's not too far. ::
Hi Martin,
I believe your reasoning is sound.
However, you may also be right to be concerned about the distance. At your distance from Central Africa, it may require a two-hop path for a radio wave to reach you.
The effect you are hoping to observe will be more profound if the path is such that only a single bounce off the ionosphere is required...that reflection point being directly along the path of the eclipse.
For that reason, I am inclined to think a station in the Arabian Peninsula or elsewhere in the Middle East might be a better candidate.
Regards,
John
Re: getting the eclipse by radio ... March 29, 2006
Posted by Martin B. on March 14, 2006 at 04:50:20.
In reply to Re: getting the eclipse by radio ... March 29, 2006 posted by John Davis on March 13, 2006
John, Re:Mast radiators on skyscrapers? - WGSO 990?
many thanks for this info. I found the page you where referencing: http://www.astrosurf.org/lombry/qsl-eclipse-d-layer.htm This page gives a lot of information, needs to be red very carefully. Also here I can read that the distance is an issue, so I'll try to find a station in Arab/Middle East. If you have a suggestion for a station/frequence in this region please let me know.
Martin
Posted by Harald on March 14, 2006 at 11:13:08.
I remember, that there was a thread, where someone asked, if there are mast radiators for medium wave on rooftops. Perhaps there is such a station in New Orleans. On http://www.fybush.com/sites/2005/site-050902.html it is claimed that WGSO 990 uses a mast radiator on the top of a highrise building. Is this correcht? Re: getting the eclipse by radio ... March 29, 2006
Posted by John Davis on March 14, 2006 at 11:58:37.
In reply to Re: getting the eclipse by radio ... March 29, 2006 posted by Martin B. on March 14, 2006
:: If you have a suggestion for a station/frequency in this region please let me know. ::
Unfortunately, I am not familiar with stations from that region, so I hope someone will have some specific suggestions for you. I can only offer these rather general ideas:
Almost any longwave or mediumwave broadcast station you can hear from that region at night would be satisfactory. In fact, you would probably hear it much more clearly than normal, since other stations from Europe or Asia are not likely to be enhanced by the temporary "night" conditions, and thus would not cause much interference.
Similarly, a powerful non-directional aerobeacon might be a good candidate, either at longwave, or just above the mediumwave broadcast band. Beacons operate with lower power than broadcasters, however, so some prior experience listening for them would be advantageous.
Any shortwave station below about 12MHz would also exhibit noticeable enhancement effects, although many of those stations would not be broadcasting during daytime hours.
You could look for the opposite effect instead, an attenuation of a shortwave station above 13MHz while the eclipse is over the midpoint of the path. However, I suspect such attenuation will be hard to distinguish from the fading that normally occurs from time to time on shortwave.
The best shortwave signals for propagation observations are usually time and frequency stations, because they normally operate 24 hours a day, always on the same frequencies. Unfortunately, I don't find any listed in either Africa or Arabia.
John
WD2XFE Off til further notice
Posted by Robert Bicking, W9RB on March 15, 2006 at 19:33:43.
My experimental 137 kHz station WD2XFE will be off until further notice. I have a website at wd2xfe.tripod.com which will show operational status. Antenna
Posted by Art on March 15, 2006 at 20:17:43.
Hello fellows...I am new to this message board and to this hobby! I just recently purchased a Rycom R1307A/GR receiver. It covers about 3 KHz to 820 KHz. Seems to hear pretty well. My question is this: what is a resonably good antenna to put up to receive these frequencies? I live in a new subdivision that does not have any antenna rules that I know of, but I dont want to create an eyesore either. I'm sure the antenna needs to be away from the house to limit those noises. All power and phone lines are underground here. Would be nice to be able to cover all of the AM BCB too. I am in Michigan and wonder if I will be able to hear WWVB on 60 KHz? Re: WD2XFE Off til further notice
Thanx in advance, Art
Posted by Warren on March 16, 2006 at 09:17:19.
In reply to WD2XFE Off til further notice posted by Robert Bicking, W9RB on March 15, 2006
Rob,
What happened? Sorry to see your station is down.
73 Warren K2ORS/WD2XGJ
Re: Antenna
Posted by Warren K2ORS/WD2XGJ on March 16, 2006 at 16:06:39.
In reply to Antenna posted by Art on March 15, 2006
Hi Art,
You are well within the coverage area of WWVB see coverage maps on their website:
http://tf.nist.gov/stations/wwvbcoverage.htm
As for an antenna, I recommend that you take a look at the posts and responses below from "New Guy" who pretty much asked the same questions. If you have any questions about a particular antenna then fire away!
73 Warren K2ORS/WD2XGJ
Re: Antenna
Posted by Art Heft on March 16, 2006 at 18:41:10.
In reply to Re: Antenna posted by Warren K2ORS/WD2XGJ on March 16, 2006
Thanx for the answer, Warren. Please email me the info on the whip antenna.
Re: Antenna
Posted by Warren on March 16, 2006 at 20:05:00.
In reply to Re: Antenna posted by Art Heft on March 16, 2006
Art,
I e-mailed you the whip plans. Let me know if you have any questions.
73 & GL Warren K2ORS/WD2XGJ
Re: getting the eclipse by radio ... March 29, 2006
Posted by Martin B. on March 17, 2006 at 08:43:44.
In reply to Re: getting the eclipse by radio ... March 29, 2006 posted by John Davis on March 14, 2006
...it's not ease to find frequences. It really took me a while to get it. I have now 2 radio stations:
Jordania on 207 kHz
Israel on 17.535 kHz
When I understood right I should loose the signal from Israel and receive Jordania. I'll try now to get the stations....
Many thanks again,
Martin
Gilfer Shortwave
Posted by g. Michael Conover on March 19, 2006 at 20:52:35.
Would anyone here have a line on any info (User Manual/Schematic) for a
Gilfer BCL Antenna Coupler Model Q5
Re: Gilfer Shortwave
Posted by Warren K2ORS/WD2XGJ on March 20, 2006 at 06:56:50.
In reply to Gilfer Shortwave posted by g. Michael Conover on March 19, 2006
Michael,
I don't have any direct info on the unit but you might try contacting Paul Lannuier who was the last owner of Gilfer. Paul has a web site:
http://www.lannuier.com/ww2pt/page.cfm?content=home
73 & Good luck!
Warren K2ORS/WD2XGJ
LW Max Software
Posted by Vern on March 22, 2006 at 03:09:26.
Does anyone have a copy of the software that came with the LW Max built by PCS Electronics, ?? If so let me know
Tks Vern Ve4Xc Ultralinear Whip - oct 2005 lowdown - transformer question
Posted by steve osborne on March 24, 2006 at 09:06:54.
Does anyone have the core and turns data for T1, T2 and T5 used in the ULTRALINEAR LF ACTIVE WHIP by John Reed (Oct 2005 LOWDOWN pg 15-17) ??
Thanks in advance - Steve Osborne KC0YA
Re: Ultralinear Whip - oct 2005 lowdown - transformer question
Posted by John Andrews on March 24, 2006 at 11:05:56.
In reply to Ultralinear Whip - oct 2005 lowdown - transformer question posted by steve osborne on March 24, 2006
Steve,
According to the text on page 16, the transformers are wound on Amidon FT-50-75 cores. The turns data are listed on the same page.
John Andrews, W1TAG Re: LowFER LEK not operational
Posted by Mike WE0H WD2XGI on March 24, 2006 at 21:08:55.
In reply to LowFER LEK not operational posted by Lyle Koehler on March 06, 2006
Sure miss your signal on the band Lyle!!! I surely can drive up to help on a TX loop install if you like. Not to fond of towers so I wouldn't want to volunteer any of that high flying stuff...LOL!!!
Later,
Mike Experimental Longwave Transmissions
Posted by Mike Terry on March 25, 2006 at 15:11:57.
Experimental Longwave Transmissions from Tower Hill,Wayland, Massachusetts
Warren Ziegler, K2ORS holds broadcaster Jean Shepard's old call. Warren experiments with longwave transmissions on 137.8 KHz.
Mode: Slow CW 60 second dots (QRSS 60), also QRSS 30, 8 wpm cw i.d.
Operating Hours: 22:00-12:00 UTC (sometimes longer)
Look at the cool stone tower where he operates his station: http://www.w4dex.com/wd2xgj.htm
Reception Reports Welcome: k2ors comcast.net
Re: Experimental Longwave Transmissions
Posted by Warren WD2XGJ/K2ORS on March 26, 2006 at 16:55:08.
In reply to Experimental Longwave Transmissions posted by Mike Terry on March 25, 2006
Hi Mike,
Thanks for the plug, but I'm only one of the many LF experimenters in the States. A fairly complete list can be found elsewhere on this web site:
http://www.lwca.org/sitepage/part15/index.htm
73 Warren K2ORS/WD2XGJ Re: getting the eclipse by radio ... March 29, 2006
Posted by Ken on March 27, 2006 at 16:43:43.
In reply to getting the eclipse by radio ... March 29, 2006 posted by Martin B. on March 13, 2006
Martin,
Another way might be to use a Satellite dish antenna and "Satellite Finder" meter to measure the the 12 GHz thermal signature of the solar disc directly. Check this website...
=> http://wi7b.org/RA/index.htm
Good luck!
---* Ken
ywa & tvx beacons
Posted by michael tyler - wa8ywo on March 27, 2006 at 21:35:39.
0220gmt i am hearing ywa on 517.16 and tvx on 521.9 kcs. any id on these? using a FT-840 and 160 meter 1/2 wave dipole.....thanks..mike Re: ywa & tvx beacons
Posted by lloyd chastant on March 28, 2006 at 08:03:21.
In reply to ywa & tvx beacons posted by michael tyler - wa8ywo on March 27, 2006
Mike I show VLF ultrasound question
517 YWA Petawawa, Ontario
521 TVX Greencastle, Ind
de Lloyd W3NF
Posted by Stan on March 28, 2006 at 09:45:42.
When reading papers on VLF (30 khz to 40 khz) using ultrasound sensors they still talk about electromagnetic waves. However, is this an EM or a mechanical signal? Seems like it would be a mechanical produced signal coming off the ultrasound sensor and it also seems like the sensor would only respond to a mechanical signal?
Does anyone have any design experience with these devices ?
Thanks, Stan Re: VLF ultrasound question
Posted by John Davis on March 28, 2006 at 17:24:01.
In reply to VLF ultrasound question posted by Stan on March 28, 2006
Without having any context from reading the papers in question, it's hard to know exactly what they mean by any such references. The transducer should principally produce an acoustic-mechanical signal, and should principally respond to one.
Of course, electromagnetic signals could leak in or out, depending on the design of the device, but I'm not sure if that's what they're talking about.
John
Re: VLF ultrasound question
Posted by Warren K2ORS/WD2XGJ on March 28, 2006 at 18:23:42.
In reply to VLF ultrasound question posted by Stan on March 28, 2006
Hi Stan,
I did a little research work and they are definitely mechanical acoustic waves. However, the signal going to/from the transducer is an electomagnetc wave propagating in a transmission line. Hope this helps!
73 Warren K2ORS/WD2XGJ
Re: VLF ultrasound question
Posted by Stan on March 29, 2006 at 10:04:05.
In reply to Re: VLF ultrasound question posted by Warren K2ORS/WD2XGJ on March 28, 2006
That was what I thought. Interesting, when traveling through "the ether' for lack of a better name it is mechanical, then converted to EM at the sensor.
I suspect the same is true for a mechanical IF filter?
Maybe RF is a black art. hi
Re: VLF ultrasound question
Posted by Alan G3NYK on March 29, 2006 at 15:34:13.
In reply to Re: VLF ultrasound question posted by Stan on March 29, 2006
Hi Stan, if you think of the wavelength, and then consider the resolution a 30kHz radar would have (about 5000m, or 3 miles), you will see the mistake. Now acoustic waves travel much slower so the wavelength is much shorter and the resolution correspondingly higher. I remember seeing 5MHz acoustic transducers twenty of so years back, they probably go up a lot further now. The device was refered to as an acoustic microscope I think.
I was trying to think whether "EM" could stand for something other than electomagnetic, but drew a blank there.
Cheers de Alan G3NYK
Re: VLF ultrasound question
Posted by Stan on March 30, 2006 at 09:21:22.
In reply to Re: VLF ultrasound question posted by Alan G3NYK on March 29, 2006
Hi ALan,
Yes EM electromagnetic. I find it interesting in that one could generate a electromagnetic wave at the sensor frequency and it would not be detected, but the sensor could still detect the acoustical wave at the same frequency. Yet the output of the sensor would be a electrical signal.
I need to study how the SAW and mechanical filters work.
ALso wonder if I epoxy two 30 khz transducers together is the new frequency now 15 khz ? Or if I slice a 30 khz one in two is it now 60 khz?
Did you see the article in QST about the power line arc detector? The interference would be electrical (and acoustical) from the radiated arc, but they detect it with a acoustical sensor.
Wonder what would happen if we replaced the transducer with a LC circuit tuned to 30 khz? My thinking is the LC circuit would be more sensitivity.
So many questions and so many experiments one can do.
Stan
Re: VLF ultrasound question
Posted by John Davis on March 30, 2006 at 13:11:08.
In reply to Re: VLF ultrasound question posted by Stan on March 30, 2006
:: I find it interesting in that one could generate a electromagnetic wave at the sensor frequency and it would not be detected, but the sensor could still detect the acoustical wave at the same frequency. Yet the output of the sensor would be a electrical signal. ::
This is what transducers do...convert one form of energy to another, selectively. In normal operation, the ultrasound transducer converts electrical energy (in the form of EM waves in the transmission line connected to it) to mechanical energy (vibrations at the same frequency) which, in turn, couple to air molecules and become acoustic waves. Conversely, the same transducer receives acoustic waves as vibrations on its surface, and converts those to electrical energy. That's what happens in the case you mention below.
:: Did you see the article in QST about the power line arc detector? The interference would be electrical (and acoustical) from the radiated arc, but they detect it with a acoustical sensor. Wonder what would happen if we replaced the transducer with a LC circuit tuned to 30 khz? My thinking is the LC circuit would be more sensitive.
An LC circuit would have almost no sensitivity at all to the acoustic energy. It might or might not pick up the electromagnetic signals, depending on the nature of the inductor. A loop would couple to the electrical signal, but a coil wound on a toroid would not.
In the case of the project in QST, sensitivity to electrical noise is not what you want. I've tried tracking down power line noise by its RF energy, and it's not easy. The power line itself acts as both transmission line and antenna, conducting the radio noise over a wide area.
Because it is a poorly matched transmission line, however, the noise level experiences a sort of standing-wave effect. It will exhibit high levels in locations far from the real noise source, and can easily mislead you.
In tracking down a particularly troublesome arc one time, the best I could do with a radio was to identify half a dozen poles scattered around the east side of town as possible sources, because the signal was almost equally strong at each. I ended up having to make a map of the likely candidates and check out each pole at night, in hopes of seeing the actual discharge. That finally pinpointed it, and I was able to tell Georgia Power where to find it the next day.
On the other hand, the ultrasound detector listens for the acoustic energy of the arc. This sonic energy is much more localized because it's not transmitted along the power line, so the acoustic signature pinpoints the source without ambiguity.
John
Re: VLF ultrasound question (sensors, IR)
Posted by Alan G3NYK on March 30, 2006 at 18:13:09.
In reply to Re: VLF ultrasound question posted by John Davis on March 30, 2006
Hi agn Stan we are all old enough to have worked on tube-gear and therefore higher voltage equipment. Sound and smell was a good guide to incipient failure. The standing joke used to be to slap a wooden rule on the bench when someone was inside a a case. It was amazing to see just how fast their hands came out despite the fact they might know it was not switched on or even plugged in.
Even on semiconductor gear other "sensors" are valuable. I remember an engineer working on some personal gear in the lab at lunchtime, with all the high tech test equipment piled up around him. The tech walked in, coffee in hand, looked over his shoulder, sniffed, wet his index finger and went down the line and said to the engineer "check that transistor stage" and wandered off with his coffee and the crossword. Yes, there was a slight "psst" as he touched the transistor.
John I have occasionally used UHF receivers for chasing pole noise, that doesnt seem to spread like lower frequencies I think the energy at those frequencies from the arc is radiated rather than conducted. The company round here use IR cameras these days as well. An idea that might be useful for the Part 5 boys finding corona with their kWs into verticals. Some of this IR kit is getting quite cheap now I wonder if its any good for that?
Stan if you get the glue up the two sensors you will get nothing out as it will damp the diaphrams !! :-))
Cheers de Alan G3NYK
Regen use for NDB ?
Posted by Stan on March 31, 2006 at 17:02:50.
Anyone using a homebrew regen for listening for the beacons just below the broadcast band?
If so how successful have you been.
Stan ak0b
potrzebie