John Re: Class
Posted by Paul on October 06, 2011 at 08:23:37.
In reply to Re: Class posted by John Davis on October 05, 2011
I didn't know there was a micro AM operating during NAB. I would have tuned it in. Oh well, I just had to research my cap-ex expedatures for next year and get out. Well, OK, I did take my wife to dinner at a real nice place, and we did spend a lot of time in the water at Mandalay Bay... Shhh....
Re: Class
Posted by John Davis on October 06, 2011 at 14:45:10.
In reply to Re: Class posted by Paul on October 06, 2011
Don't worry, Paul, your secret is safe with me. :) What happens in Vegas stays in Vegas, you know.
I didn't get to go this year--in fact, it's been a few years now--but I doubt the transmitter in question is still around. Caused a bit of a furor at the time, as I recall.
John
Lowfer SIW QRV
Posted by Garry, K3SIW on October 06, 2011 at 16:36:48.
Bob, NK9M and I fired up lowfer SIW this afternoon from EN51uq. This year's version is to switch at 1800Z to 185.185 kHz (Tuesday, Thursday, and Saturday) and to 185.2993 kHz (Monday, Wednesday, Friday, and Sunday). Time will tell if that works as intended. Transmissions consist of "SIW" sent at QRSS60 rate.
Garry, K3SIW, EN52ta, Elgin, IL
JAM antenna details
Posted by Lee on October 07, 2011 at 02:25:40.
Well I saw a recent post about open frame coils and decided to measure the coil of beacon JAM. I recently aquired one of those Chinese L/C meters for $32.00 off of E-Bay. It came literally from the manufactuer in China. Cool. The coil value I got for the winding that produces max antenna current at 187khz is 2.218 mh. Using that number to do the math I come up with a total CAP value of about 327pf. Thats the mast and tophat combined. So I am thinking the actual top hat value is 300pf plus. Like Real Estate Exec's Lowfers have a montra. Tophat, Tophat, Tophat. Re: Class
73zzzzzz
Lee
Posted by Rev. Robert P. Chrysafis on October 07, 2011 at 06:14:24.
In reply to Re: Class posted by John Davis on October 06, 2011
I'm hoping what will happen with my sstran amt5000 is (since it will be indoors) is power line coupling of the RF signal and i wind up with more of a carrier current effect. since the building is brick and steel i doubt it will radiate much beyond the building itself. of coursem y backup is an AX10 stereo exciter into a cunningham CM20-30 turned down to two watss into a cunningham universal coupler/tuner and neutral loaded to the power on the low end of the am band.
I just have to locate a local who is willing to help me verify F/S from building with a FIM if i went that route.
Re: Class
Posted by Rev. Robert P. Chrysafis on October 07, 2011 at 06:17:27.
In reply to Re: Class posted by Rev. Robert P. Chrysafis on October 07, 2011
ps: the board used to notify of replies. i seem to no longer receive the alerts about replies to my email when posting. was there a change in the forum software or settings?
Re: Class
Posted by Webmaster on October 07, 2011 at 10:14:38.
In reply to Re: Class posted by Rev. Robert P. Chrysafis on October 07, 2011
Sorry, Robert. This particular board has never included email notice of replies. In fact, that's the main reason why I added the Most Recent Messages window, to make it a little easier to find whether someone has replied.
John
Re: Class
Posted by Rev. Robert P. Chrysafis on October 07, 2011 at 10:20:20.
In reply to Re: Class posted by Webmaster on October 07, 2011
oh ok. I am on alot of message forums. must have confused this one for another forum as far as notification.
Digital Copies of the lowdown
Posted by Rev. Robert P. Chrysafis on October 07, 2011 at 10:59:41.
is the lowdown available in pdf? and i mean all the past issues as well. I am looking into finding an E-Reader that will take a 32GB SD card and i'm looking to put the lowdown and scans of my other low power am tech manuals to pdf so i can carry them all with me on an E Reader. carrying an E Reader would be more palatable to the XYL then carrying a notepad and books lol. I have the paper copies of the lowdown that were offered up on here few months back and just got around to really reading them and i'm intrigued by some of the schematics and designs. it would be interesting to be able to carry that library with me to read in the car or other places while out and about. if they are not available, maybe someone can give me some tips on how to efficiently scan the ones i have to pdf and recommend an E reader that will take the 32GB card and be able to do pdf. prefer B&W screen as ive been told it has longer battery life then the color. I don't need wifi or any of that other stuff. also would there be any issues with the publisher if i were to do this for personal use and not for redistribution.
Thanks,
Robert
Re: JAM antenna details
Posted by Rev. Robert P. Chrysafis on October 07, 2011 at 12:55:44.
In reply to JAM antenna details posted by Lee on October 07, 2011
is the circumference of the tophat part of the 15 meter limit? or is it like a coil and since it doesn't actually radiate it's added height is all that considered?
Re: JAM antenna details
Posted by Lee on October 07, 2011 at 13:37:42.
In reply to Re: JAM antenna details posted by Rev. Robert P. Chrysafis on October 07, 2011
The tophat radials are 15 feet in length with a skirt wire connecting the tips of the radials on top of a 30 ft mast.
Re: JAM antenna details
Posted by Rev. Robert P. Chrysafis on October 07, 2011 at 13:46:43.
In reply to Re: JAM antenna details posted by Lee on October 07, 2011
ok. guess that answers my question. that is what i had heard. i misspoke it should have been radius and that is what it looks like that the radius of the top hat is indeed counted in the 15 meter limit.
thanks
Re: Digital Copies of the lowdown
Posted by Webmaster on October 07, 2011 at 22:12:16.
In reply to Digital Copies of the lowdown posted by Rev. Robert P. Chrysafis on October 07, 2011
Robert, I'm not an expert on all the e-readers out there, but I think you'll find you will need WiFi and that other stuff. That's how they send you content that you buy from a publisher...and that's the main purpose of these devices.
In the case of Kindle, I know that you can e-mail PDF files and other personal content to your reader. (Here is a link to the Kindle 6" E Ink Display
However, you can't insert your own card and transfer files into or out of the reader. That would raise too many opportunities for copyright violation. Publishers aren't going to let their work be distributed by any method that effectively means ONE copy actually gets sold, while millions of other copies in circulation are pirated. For that reason, they do not license their content to electronic distributors who don't have anti-copying safeguards built into the product.
The certainty of intellectual property theft is also why we do not make PDF copies of LOWDOWN back issues available. We've considered the idea several times before, but always had to turn it down. Most of us who write for the publication are happy to make some of our material freely available for the benefit of our fellow hobbyists, but some of it is explicitly copyrighted by authors who wish to protect the commercial value of their work, and we are obliged to honor their wishes if we want to print it. Now, I say "certainty" of theft, not "chance," because it has happened every single time we've tried to make a copyrighted article from The LOWDOWN available on the Web. I could go on for hours about that, but I'll spare you the gory details for now!
Here's one thought: If you're mainly interested in reading content that you've collected and/or scanned yourself, for your own use, you may be more in the market for a tablet computer than an e-book reader.
On the other hand, without divulging too many details that may turn out only to be speculation, we are looking into the possibility of publishing back issues, or even an electronic subscription edition of the magazine, for e-readers! Since these devices do provide some degree of protection for intellectual property, the idea may finally be feasible after all these years.
Ironically, the main thing standing in the way right now is that the e-readers may be too restrictive in what the user can do with the magazine. Most of them seem to make no provision for printing specific pages as hardcopy. While much of the publication can be read well enough in electronic form, you wouldn't want your nice expensive screen sitting there on the workbench getting solder dripped on it while you build a featured circuit! We'll want to be sure members can obtain paper copies of schematics and drawings for that purpose.
I don't anticipate any announcements in the near term, but maybe we'll have something worked out next year.
John
Re: Digital Copies of the lowdown
Posted by Rev. Robert P. Chrysafis on October 08, 2011 at 07:39:01.
In reply to Re: Digital Copies of the lowdown posted by Webmaster on October 07, 2011
I found this one and even has located it for around 100.00 plus shipping...
http://www.ectaco.com/main.jsp?do=products-view_item&item=19497&refid=29532
can be expanded up to 32gb has B&W screen no wifi, reads pdf, but the screen is only 5" IDK how that screen size would compare in readability to the kindle.
if i could find it with a screen like the kindle i would jump on it and get a 32gb chip. i have been thinking of a tablet pc as well. they're still a bit pricey for someone on a fixed income. the E-Readers are more reasonable, but it would be nice to have the tablets internet/email capability in addition to the ereader.
Re: Digital Copies of the lowdown
Posted by Webmaster on October 08, 2011 at 09:50:11.
In reply to Re: Digital Copies of the lowdown posted by Rev. Robert P. Chrysafis on October 08, 2011
Yes, the Ectaco unit looks like it meets your stated requirements. I have had a little experience with one of the company's translator products, and it seemed pretty solid and dependable, so I would expect the same from this unit. The smaller screen should only be a minor inconvenience at most, since it lets you adjust type size to your own preference.
Downside: It is strictly a reader, though, and requires you to gather whatever material you want to carry around with you on your computer first. It cannot be used to purchase/download books or periodicals from a publisher, like the Kindles or iToys can. That's a capability you would need if we do decide to publish an electronic edition.
John Re: Class "E" 1750 meter transmitter with an air wound base load antenna
Posted by John Davis on October 08, 2011 at 11:13:54.
In reply to Re: Class "E" 1750 meter transmitter with an air wound base load antenna posted by Rev. Robert P. Chrysafis on October 03, 2011
:: if you run AM (maybe a very narrow AM, say 6khz?) with the previously quoted design ideas what kind of improvement would you see over a class c amp with a base loaded 15 meter antenna over a small ground plane as typically employed by lowfers?
In re-reading this thread, it appears there may be some benefit in clarifying a point or two.
Few, if any, LowFERs still use Class C finals. Most operation is done with Class E or Class D already, and both can be equally efficient if adequately designed (90-95%, compared with 70-80% for Class C). The difference between D and E is basically the use of two switching devices in Class D amplifiers (forming a SPDT switch that toggles the output between two supply rails, or between one supply and ground) versus one in Class E (an SPST switch to ground using an inductor in a commutating configuration to pump charge into and out of the output coupling capacitor).
As with most every topic that finds its way onto the Web, there is a lot of incomplete or downright misleading information about amplifier modes. Some articles give the impression all Class D amplifiers are pulse-width modulated amplifiers for producing high level audio outputs efficiently--and this is certainly one popular application. But "Class D" has nothing to do with the nature of the output signal. With a different output filtering network and a continuous near-50% duty cycle for both transistors, you can just as easily output a nice clean stream of RF at the switching frequency. This is the principle behind the popular Lyle Koehler output stage used in a lot of contemporary LowFER transmitters.
Knowing this, you might even consider modulating the drive pulse widths (as in audio amplification by Class D) to amplitude modulate the signal, thus killing two birds with one stone by obviating the need for a separate modulator stage. In principal, this would work, but the higher the carrier frequency, the harder it is to switch the very narrow pulses that would be required at modulation extremes. Circuit complexity would increase and efficiency would decrease somewhat.
Instead, it is better simply to treat the Class D RF amplifier as a switching device that converts DC to RF, and modulate the supply voltage as with any other high-level AM transmitter. The drawback is that device saturation characteristics change with supply voltage fluctuations, so efficiency (and perhaps linearity) suffer at modulation extremes. This can be compensated with careful design, but it may be more trouble than it's worth at the low power levels we are using anyway. Therefore, most Class D LowFER finals are simply used for CW and FSK or PSK transmission modes.
Class E, the single-ended switching mode, can be high-level amplitude modulated with good linearity. Its disadvantages are that the output device must be capable of withstanding four times the supply voltage to account for the peaks that occur in normal operation. For AM, that means a minimum of 4 times TWICE the resting DC voltage, since 100% positive modulation will instantaneously double the carrier voltage. In selecting the voltage rating of the final transistor, one must also allow for the possibility of accidental overmodulation and the occasional tuning network defect, so the Vd(max) of the MOSFET will need to be several times than the resting supply voltage.
In addition, Class E stages often need specialized driver circuitry because of the high gate capacitance of MOSFET devices. However, this is more of a concern at high power levels. For the smaller MOSFET devices generally used in LowFER transmitters, plain old CMOS buffer amplifiers usally provide sufficient drive.
John Re: Digital Copies of the lowdown
Posted by Rev. Robert P. Chrysafis on October 08, 2011 at 11:14:53.
In reply to Re: Digital Copies of the lowdown posted by Webmaster on October 08, 2011
for reasons stated earlier i probably wouldn't subscribe to any periodicals electronically or otherwise.
Re: Class
Posted by Rev. Robert P. Chrysafis on October 08, 2011 at 11:17:04.
In reply to Re: Class posted by Rev. Robert P. Chrysafis on October 07, 2011
here are pic's taken during the sstran amt5000 assembly as i completed each stage in manual.
https://www.facebook.com/media/set/?set=a.111925762250395.16947.100002989142408&l=65d972012a&type=1
i am still waiting on some missing parts to come from phil. they are probably already at moms but i wont be getting there till monday.
Re: Class "E" 1750 meter transmitter with an air wound base load antenna
Posted by Paul on October 09, 2011 at 11:19:08.
In reply to Re: Class "E" 1750 meter transmitter with an air wound base load antenna posted by John Davis on October 08, 2011
Good info, John.
Hadn't actually considered this. You're right.
One of my AM stations has a 10 KW class E transmitter, and I am impressed by the linearity of it. Oh, and it would probably pass an FM audio proof.
I have a few lower power level class E rigs on the air too (500 watts and 1 KW) and they all show fantastic overall efficiency. That translates to lower power bills, and especially less air conditioner usage to cool them.
Hadn't considered the LOWfer application, but good food for thought. Might have to draw up a class E circuit for 170 MHz. and play around with it a little.
Re: Class "E" 1750 meter transmitter with an air wound base load antenna
Posted by John Davis on October 09, 2011 at 21:31:36.
In reply to Re: Class "E" 1750 meter transmitter with an air wound base load antenna posted by Paul on October 09, 2011
Yup, a really good AM transmitter can achieve FM performance levels. Too bad there are usually such noisy paths between transmitter and receiver that we never get to appreciate the possibilities.
There was actually a time shortly before the popularity of Lyle's complementary switching pair when Class E looked like it might become common among LowFERs because of the ease of driving a fairly inexpensive output transistor with readily available CMOS logic. My first LowFER beacon SE (later SEA) down in Georgia was one of those.
I did manage to damage a few finals, however, partly because I did not understand the function of the shunt capacitance at first, and partly because the output network of a Class E amplifier likes to look into a load with a well defined resistive impedance. This means you may have to take a little more care in antenna matching, including a tapped RF transformer following the series resonator, to achieve the impedance your series LC network is designed for. You might be able to resonate the network into some other load, but the waveform at the collector or drain won't be ideal for good efficiency. If the voltage isn't zero when the transistor turns on, and/or if the current isn't zero when the device tries to switch off, there may be spooky transients and there will be plenty of extra loss.
Class D finals are more forgiving of what's on the other side of the series LC network; but if you use its ability to cheat a little and merely compensate by changing input voltage to achieve correct power, you'll pay a price in efficiency.
John
DCF 77
Posted by Larry Lanberg on October 11, 2011 at 21:16:36.
First time catch of the German time signal on 77.5 kHz, a good aural copy. I'm on the East Coast of the U.S. It was a surprise, I wasn't trying for it. Using a homemade ferrite loopstick (actually wound for the LWBC Band) and a homemade single-transistor preamplifier on my Mackay 3030A receiver.
I don't know how often that station makes it here to the U.S. I'm thrilled enough to post about it.
beacon list 500 khz
Larry
Posted by doctor795 on October 12, 2011 at 06:24:49.
Looking for a beacon list OUTSIDE USA...for Europe etc... on the Internet High Medfer Beacon Antenna
Thanks
doctor/795
Posted by Pat Bunn on October 13, 2011 at 08:07:18.
I am planning to install a Medfer beacon at Edisto Beach SC using a 10 foot vertical with a large capacitance hat. The beacon will be installed on a treated 4 x 4 post in about 2 feet of saltwater in a narrow saltwater creek behind my house. I plan to install 3 -4 ground rods at the base of the 4 x 4.
What are opinions about installing ground wire radials under the water in the creek off the ground rods? Am I legal as if I were using a metal roof or is this part of the antenna?
Pat Re: Class "E" 1750 meter transmitter with an air wound base load antenna
N4LTA
Posted by Paul on October 13, 2011 at 09:49:07.
In reply to Re: Class "E" 1750 meter transmitter with an air wound base load antenna posted by John Davis on October 09, 2011
Yes, but if you use high drive and lower output by lowering supply voltage, you will also not have to worry much about the final overheating due to poor load.
One of the nice things about class C is that when the load becomes less than ideal, resonance is lost and output drops accordingly, sometimes saving the device. Especially true if you derate the supply voltage for power control rather than lower the drive level.
Re: High Medfer Beacon Antenna
Posted by Paul on October 13, 2011 at 09:50:44.
In reply to High Medfer Beacon Antenna posted by Pat Bunn on October 13, 2011
Ground radials in the consuctive water/soil would be ideal. Especially if they are numerous.
Although it doesn't exactly meet the letter of the law, it is an area that is not well enforced.
Re: High Medfer Beacon Antenna
Posted by John Davis on October 13, 2011 at 12:13:50.
In reply to Re: High Medfer Beacon Antenna posted by Paul on October 13, 2011
Actually, the surface of the water should adequately represent your ground connection point since that's where the ground return current will be concentrated; and the Rules don't specify that a ground connection equates to soil. But if you want to be on the cautious side, simply subtract the 2' creek depth from your antenna length.
In fact, if you had a way to suspend the radials just under the surface, that would be your most effective connection to saltwater. The soil of the creek bed would almost not have to interact with your RF at all that way.
John Re: Class "E" 1750 meter transmitter with an air wound base load antenna
Posted by John Davis on October 13, 2011 at 12:35:35.
In reply to Re: Class "E" 1750 meter transmitter with an air wound base load antenna posted by Paul on October 13, 2011
:: ...if you use high drive and lower output by lowering supply voltage, you will also not have to worry much about the final overheating due to poor load.
True, and this is often a worthwhile tradeoff over sheer efficiency alone, given the load fluctuations that are sometimes encountered with 1750 meter Part 15 antennas under weather extremes.
It is also the basis for a technique Lyle Koehler demonstrated some years ago for maintaining legal DC power input under conditions of mistuning. If efficiency outside the final P.A. is not a concern (in other words, if power conservation is not a rigid requirement of the installation), then the operator can use this technique:
1. Set up the transmitter and antenna for best tuning and correct 1 W DC power input under normal operating conditions.
2. Note the voltage and current at the input of the final for that 1 W power.
3. Build a regulated power supply that furnishes twice the voltage noted in Step 2.
4. Using R=E/I, where E and I are the values determined in Step 2, calculate the value of a ballast resistor to insert in series between the PA's power input connection.
If the antenna tuning wanders, the radiated power from this setup will fall off until the operator gets around to re-tuning, but the DC input power will not exceed the legal limit, and one is very unlikely to damage the final transistor(s). This is a technique Lyle used with his Class D PAs, but it should be beneficial for other modes as well.
John
Re: High Medfer Beacon Antenna
Posted by Pat Bunn on October 13, 2011 at 17:50:10.
In reply to Re: High Medfer Beacon Antenna posted by John Davis on October 13, 2011
John,
My thought was to run the wires up and down the creek a 1/4 wave or so under the surface. The water is 2 feet deep max and drops to 6" or so at low tide.
The question is are the ground radials considered part of the antenna or should I just rely on the salt water and salt mud as a ground.
Either way, I would think it will make a pretty good Medfer antenna.
Re: High Medfer Beacon Antenna
Posted by John Davis on October 13, 2011 at 22:14:06.
In reply to Re: High Medfer Beacon Antenna posted by Pat Bunn on October 13, 2011
Ah-ha. That clarifies things a bit, even if it does somewhat complicate the goal of efficient radiation. Remember the wording of the applicable rule:
Section 15.219 Operation in the band 510 - 1705 kHz.
. . . .
(b) The total length of the transmission line, antenna and ground lead (if used) shall not exceed 3 meters.
. . . .
Radials, ground rods, metal water pipes...the type or composition or area of the ground system does not figure into the calculation in any way, only the length of the lead from your transmitter to the grounding arrangement.
Since a foot and a half of that connection will be exposed for some length of time twice each day, that much length would need to be figured into your calculation of total length of transmission line, antenna, and ground lead. As a practical matter, the constantly changing antenna-plus-ground-lead length caused by those tides will also affect your tuning significantly! This is the bigger problem, which we'll look at in a moment.
Lengthening the ground radials to a quarter wavelength will not mitigate the tuning difficulties, unfortunately, and is not too helpful for signal strength either. Most of the length of a long radial would be carrying immeasurably small RF current because it's out of the "reach" of the electric field of the radiating element! With electrically very small antennas, the number of radials is far more important than their length.
The objective is to provide as low-loss path as possible for the antenna displacement current "returning" to the transmitter, and that includes keeping the distance it has to travel in the ground before reaching copper as short as possible. Where the electric field is strongest (ie, near the base of the radiator), that's where the most metal needs to be. In the electrically short monopole, a ground radial needs to be somewhat longer than the height of the radiating element to account for fringing of the field, but after you get beyond 10-20% longer, you enter the realm of diminishing returns very quickly.
Now...what to do about those tides? Even the thought I offered in my previous post (about a counterpoise right at the surface of the water) won't stabilize tuning if the water level under the counterpoise keeps changing.
The best solution, electrically, would probably be a floating antenna platform having its underside lined with as much metal as practical for good connection to the salt water! However, whether that's a physically practical, or mechanically stable, or even environmentally sound idea in your location, I could not say.
Alternately, if you could somehow trap a tidal pool that would maintain water level consistently enough between tides, you could perhaps install the rig and ground in the middle of that.
Failing those possibilities, the next best solution would simply be to mount the transmitter and antenna on terra firma and run just as many radials of the ground system as possible into the salt water environment. "Close" counts not only in horseshoes and hand grenades, but also when employing saltwater conductivity to enhance mediumwave coverage.
John Medi 1 Morocco 171 khz in SW US
Posted by Ward K7PO on October 14, 2011 at 21:03:27.
Hearing Morocco again on 171 khz tonight, ~59 , strongest ever for me here in AZ. My window seems to be 0330Z - 0400Z. I've been hearing them each night this week at about the same time. Got positive ID (since I don't speak Arabic or French) by clicking on their live feed on the Medi 1 web page. Best s/n setup here was PA0RDT e probe, hb upconverter, and 756 PRO II. If nothing else, it confirms my hb stuff works!
OK, being 40 miles west of Phoenix, out in the desert, with almost no noise might help a little.
Ward K7PO Re: Medi 1 Morocco 171 khz in SW US
Tonopah, AZ
Posted by John Davis on October 15, 2011 at 09:38:26.
In reply to Medi 1 Morocco 171 khz in SW US posted by Ward K7PO on October 14, 2011
Congratulations, Ward. That is mighty good reception, especially for being so far inland. Almost half the path between you and them consists of the continental U.S. (and maybe some of the Canadian maritime provinces, depending exactly where the transmitter site is).
I, too, have noticed that "window" effect on their signal, with a peak an hour to an hour and a half after dark.
John
Re: Medi 1 Morocco 171 khz in SW US
Posted by Larry Lanberg on October 15, 2011 at 10:35:12.
In reply to Re: Medi 1 Morocco 171 khz in SW US posted by John Davis on October 15, 2011
My window for this station, here on the East Coast, starts precisely at 0200 UTC every night. The signal jumps from weak to very good/strong rather dramatically at that exact time. Then after midnight it starts to weaken again. I sought a reason.
When I set the grey line map at 0200 UTC I see a perfect symmetry of darkness around both locations, there and here, at that time. I don't know if that's the reason.
Hifers copied today
Posted by Sal,K1RGO on October 19, 2011 at 09:35:18.
Good conditions today, arnd 11:15 local, I copied MP and NC, got captures too. MP was 539 wid QSB and NC 529 wid gud capture ( set QRSS3). Also copied GNK wid big time QSB 529 to fade out. Re: Medi 1 Morocco 171 khz in SW US
later..........Sal, K1RGO
Posted by Alex NX1T on October 20, 2011 at 17:12:01.
In reply to Medi 1 Morocco 171 khz in SW US posted by Ward K7PO on October 14, 2011
Hi,
I am a newcomer to LW, but with a short Beverage antenna (~150 ft) had no problem copying Medi 1 last night.
Will be interesting to see how that compares to my homebrew ferrite loop.
Re: Medi 1 Morocco 171 khz in SW US
Posted by Ward K7PO on October 20, 2011 at 19:20:19.
In reply to Re: Medi 1 Morocco 171 khz in SW US posted by Alex NX1T on October 20, 2011
Hi Alex,
Yeah, you east coast guys get all the DX,HI! It seems that no matter what I want to hear, I'm usually in the wrong part of the US. Here in central AZ, I've only recently gotten my RX setup working well enough to hear on the low freqs. I went to an e probe antenna, upconverter, and the the station receiver. Just for experimentation, I tried to listen for Medi 1 on my other rigs. With any antenna/RX combo I tried, the BC band intermod and crud wiped out all traces of the LW station. I'd be interested to hear about your ferrite loop results.
Ward
Re: Medi 1 Morocco 171 khz in SW US
Posted by John Davis on October 20, 2011 at 21:12:59.
In reply to Re: Medi 1 Morocco 171 khz in SW US posted by Alex NX1T on October 20, 2011
Congratulations, Alex.
One question, though, without meaning to be argumentative or anything: why do you call your antenna a Beverage?
Regards, Re: Medi 1 Morocco 171 khz in SW US
John
Posted by Alex NX1T on October 21, 2011 at 00:09:42.
In reply to Re: Medi 1 Morocco 171 khz in SW US posted by John Davis on October 20, 2011
>> One question, though, without meaning to be argumentative >> or anything: why do you call your antenna a Beverage?
Well, it meets the definition of a practical Beverage antenna on 3.5 mhz and up :)
I suppose down on LW where it not even approaching 1/16 wave its technically something else. Its a terminated wire antenna.
Its original purpose was to provide a receiving antenna on 80/160 - as much as I could fit going east on my suburban lot, but I tried it for LW anyway and it works - better than anything else I got at the moment. Will try receiving loops specifically for LW next.
Yeah I wish I had the space to run one a couple of miles long hi hi. But in the real world will have to settle for what I can do
Re: Medi 1 Morocco 171 khz in SW US
Posted by Alex NX1T on October 21, 2011 at 00:23:59.
In reply to Re: Medi 1 Morocco 171 khz in SW US posted by Ward K7PO on October 20, 2011
It used to be that way when I lived in the city. I basically gave up on any LW attempts - just the noise floor and the intermod from medium wave BC's made it a losing proposition.
The intermod sometimes showed up all the way up to 3.5 mhz. I lived 7 miles away from a local 50 kW AM station and 3-4 miles from a 5 kW one. Even on a receiving loop located outdoors, it was just not going to work.
But I could make a ferrite loopstick crystal radio work to hear both of them loud and clear, hi hi! Now it won't but at least I can hear Medi 1. I'll take that.
Here is another thought.
Is it feasible to use one of those phase-canceling noise canceling gadgets, a short noise antenna and... powerlines for Rx?
Of course with the amount of junk on residential power lines today its probably another losing prop. I wonder if it would work 50 years ago.
Decided i want to part with a homemade medfer Tx
Posted by Rev. Robert P. Chrysafis on October 21, 2011 at 09:02:41.
selling my last gittings/mlr transmitter and bag of spare parts for 250.00 plus shipping.
comes with a huge bag of spares, RF Deck, AIR wound coil, and Modulator deck...
here are pic's
https://www.facebook.com/media/set/?set=a.101290786647226.2071.100002989142408&type=1&l=33c137f809
been told it can achieve close to a watt and still maintain asymmetrical modulation.
i do have schematics as well on this transmitter
Re: Medi 1 Morocco 171 khz in SW US
Posted by John Davis on October 21, 2011 at 09:31:28.
In reply to Re: Medi 1 Morocco 171 khz in SW US posted by Alex NX1T on October 21, 2011
OK, thanks for the clarification.
One thing I have noted in LF work over recent years is an increasing tendency to call any terminated wire antenna a "Beverage," which as I see you recognize, is not the right term at frequencies where the antenna is well below one wavelength. (I'm not entirely sure some of the guys who use the word are even terminating their antennas, for that matter.)
Even if not working on the wave principle, a terminated wire antenna can still possess enough directional properties to be useful for interference rejection. If the termination resistance is the correct value and the ground losses are not excessive, for instance, the terminal voltage resulting from the non-directional E-field pickup and the inherently figure-8 H-field pattern of the equivalent loop formed by the wire and its return path may even be closely enough balanced to produce a nice cardiod shape. Most wire antenna users depend on luck for this outcome, but with a little further care in design, it's basically the same principle exploited by such popular antennas as the EWE or the K9AY loop.
As an aside, I offered an analysis similar to the above of the K9AY loop's operation some years ago, actually, but the reaction by some of its True Believers was "No, no, no, balancing the H-field pickup of a loop with its E-field pickup can't possibly account for the miracle results, it's got to be sheer freakin' magic... gravity waves... tachyons... assorted other pseudosciencefictionology." ;) However, I have since read Gary Breed's own explanation of the operating principle (found near the end of k9ay_orig.pdf) and it's clear he applied sound engineering to the development of the antenna, not the "dark arts."
(As a further aside, when I was looking up that link again to post it here, I ran across a review from someone who was gushing on about the marvelous "gain" of a K9AY loop. Give us a break! A loop antenna whose perimeter mustn't exceed about a quarter wavelength? It may have less loss than another antenna, or you may be using a good preamp with it, but it has no "gain" of its own! --just interference rejection, which is certainly nothing to sneeze at in the LF spectrum.)
At any rate--and back to the topic at hand--your setup seems to work well. If you're inclined to experiment, you might find it productive to try different values of termination (maybe even a ground return wire) when not using it as an HF Beverage, to see if you can achieve greater directionality at LF. Of course, where you are located now, a modest sized loop antenna might be worthwhile, too.
73 SAQ UN Day Extra Broadcasts
John
Posted by Alan Gale on October 21, 2011 at 15:11:47.
From Lars Kalland:
EXTRA GRIMETON RADIO/SAQ TRANSMISSIONS
There will be two extra transmissions with the Alexanderson alternator on 17.2 kHz because of the United Nations day, Monday October 24, 2011.
The first transmission is a special transmission from young students in Sweden and will start up tuning at about 10:10 UTC and with a message at 10:30 UTC.
The second transmission will start up tuning at 17:30 UTC and a message at 18:00 UTC.
We do not require any QSL-reports on these transmissions and will not verify.
The traditional Christmas transmission will take place on December 24, 2011 at 08:00 UTC.
Regards
SM6NM/Lars Re: Medi 1 Morocco 171 khz in SW US
Posted by Alex NX1T on October 21, 2011 at 15:44:47.
In reply to Re: Medi 1 Morocco 171 khz in SW US posted by John Davis on October 21, 2011
Thanks for the K9AY loop article, I have room for one, maybe one of the things I will eventually try here.
I just read the writeup on the PA0RDT e-probe yesterday. Sounds interesting. I was always inherently mistrustful of active antennas as being prone to intermod but I guess if carefully constructed and located, a lot of people have had good results with those.
I envision using one of those as maybe a wideband local noise antenna and using a phasing gadget like the MFJ-1025, but built specifically for LF to cancel noise from my "terminated wire" antenna. This would be
I have used a high impedance buffer circuits on my ferrite loopstick type of antennas with moderate to good success and the idea seems to have potential to be exploited.
The thing with high impedance buffers is to provide a high degree of isolation to prevent noise conducted via the coax braid from reaching the high impedance circuit and coupling to it (won't take much.) And on LF it will take a lot of inductance for a braidbreaker, something to present at least 500 ohms at 100 khz, or lower (more is better).
I ran into this issue with my ferrite receiving loop I was using for 160m. For the longest time I could not figure out why it was very nice and quiet when placed outside and connected to a battery-powered radio via a short length of coax. And when connected to a long feedline back to the shack, all kinds of hash showed up. Turned out coax was conducting RFI which was then picked up by the loop high impedance FET follower. A hefty braid breaker on the coax (400 uH) fixed that.
So I am not sure whether to try a loop first or the e-probe. I am copying another broadcaster on 183 khz but just below the PL noise floor. Would be nice to "phase" is out.
Re: Medi 1 Morocco 171 khz in SW US
Posted by John Davis on October 21, 2011 at 16:01:49.
In reply to Re: Medi 1 Morocco 171 khz in SW US posted by Alex NX1T on October 21, 2011
Carefully designed active antennas are pretty robust these days (though you'll still find a lot of half-baked designs on the Internet), but e-probes are not particularly magic. The term itself is even something of a misnomer. In reality, they are off-center dipoles, with some extent of the coax braid or the mounting pole providing the other leg of the dipole. As such, they are susceptible to the same noise pickup and conduction problems you've encountered before. Depending where you "break" the braid, you may also "break" the dipole, so this is something to be aware of. We've got an article coming up in the November LOWDOWN that may be helpful in understanding this topic better.
John ONLINE RECEIVER WILL BE AVAILABLE FOR SAQ TRANSMISSION MONDAY OCT 24
Posted by Todd WD4NGG on October 23, 2011 at 11:10:02.
An online receiver will be available for the Oct. 24 SAQ transmissions at 1030UTC and 1800UTC. Lionel Loudet will have his online receiver at this
web address :
http://spectrumlab.loudet.org/
Lionel will be using a remote loop antenna located outdoors 100ft away from his receiver so his reception should be much improved this time.
The 1800UTC transmission should be interesting as this will be midday along the Eastern USA on Monday and early evening in parts of Europe.
73 - Todd WD4NGG
SAQ Tuning Up
Posted by Alan Gale on October 24, 2011 at 03:22:48.
SAQ currently tuning up with carriers and "vvv de SAQ" messages at 1020utc. Not as strong as usual here this morning.
SAQ LIve Video Stream
Posted by Alan Gale on October 24, 2011 at 03:28:26.
Those of you who can't hear the broadcast can see video of it streamed live from here: http://www.unday.org/video/
SAQ Live Video Stream
Posted by Alan Gale on October 24, 2011 at 03:28:38.
Those of you who can't hear the broadcast can see video of it streamed live from here: http://www.unday.org/video/
Hifers heard today
Posted by Sal,K1RGO on October 24, 2011 at 09:47:29.
At 12:20 local today, good copy with captures of NC,SIW,and MP. All coming through abt 539.........also copied GNK ,weak wid QSB...... SAQ Tuning up for 1800utc broadcast at 1710z
later..Sal
Posted by Alan Gale on October 24, 2011 at 10:12:48.
Hi All,
If anyone is planning to try and catch the 1800utc broadcast from SAQ, please note that they are currently transmitting a carrier on 17.2 kHz, which is interspersed with short 'vvv de SAQ' announcements at various intervals.
Hope it propagates well across the big pond this time.
Re: Hifers heard today
73 de Alan.
Posted by Garry, K3SIW on October 25, 2011 at 07:03:09.
In reply to Hifers heard today posted by Sal,K1RGO on October 24, 2011
Sal, thanks very much for the report. Glad to know hifer SIW is still getting out of the back yard. It doesn't bother lowfer reception so will keep it on over the winter.
73, Garry, K3SIW, EN52ta, Elgin, IL
Re: Hifers heard today
Posted by Sal,K1RGO on October 25, 2011 at 08:20:57.
In reply to Re: Hifers heard today posted by Garry, K3SIW on October 25, 2011
Same here Garry, I keep mine on all the time except when tuning in hifers..... Re: Decided i want to part with a homemade medfer Tx
later.......... Sal
Posted by Rev. Robert P. Chrysafis on October 25, 2011 at 13:03:31.
In reply to Decided i want to part with a homemade medfer Tx posted by Rev. Robert P. Chrysafis on October 21, 2011
i also have some emails from Dr. Jack Gittings I Believe which detail setting it up for 100mW input to final stage.
Re: Hifers heard today
Posted by Paul on October 25, 2011 at 16:03:22.
In reply to Re: Hifers heard today posted by Sal,K1RGO on October 25, 2011
Mine is on 24/7 also. It's over 60 miles away, so turning it off requires a drive...
" PBO" On the air !
Posted by Rick KA2PBO on October 26, 2011 at 14:50:52.
Hi All,
I have fired the beacon up for the season. New stepdown xfrmr and exiter for the loop final. I think I am off frequency a few Hz .My counter is showing 187.1994 khz.
Will announce when I take it off air to do some listening.
Good Luck !!
Rick 2200 meter operations
KA2PBO
"PBO" 187.2 Khz QRSS 60
Posted by Mark Dittmar on October 28, 2011 at 07:53:00.
I know that there are several north american experimental stations in the 2200 meter band. I'm trying to find out if any are currently operational and what mode they are running. Seems like mostly QRSS30 and QRSS60. I'd like to try copying them with ARGO this weekend but would be good to know if anyone is even transmitting.
Thanks for any info !
Re: 2200 meter operations
Posted by John Davis on October 28, 2011 at 10:14:53.
In reply to 2200 meter operations posted by Mark Dittmar on October 28, 2011
Our listing in the LowFER section of this site is about as current as it can be, as these stations operate more on the ham model than the beacon model. Most of them will be on a given frequency for anywhere from a single QSO up to a few days, and then will do something else.
The most consistent station is VE3OT, which uses the MP ident for beacon operation in QRSS30, with the legal ID sent in regular CW just before each "MP" sequence. Mitch is on 137.7805 as a rule, and he operates summer and winter.
This is near the top of the North American "watering hole" segment of 2200 meters. As winter approaches, more stations tend to be on within a few Hz of there, although some of them are intermittent at best. Best times to catch the most guys on the air is the weekend, of course. If you can only run one session of Argo, you might not see the entire watering hole on a single screen, but if you run two Argo sessions (one tuned higher than the other) or use Spectran with appropriate settings, you should be able to watch the most frequently used slots simultaneously.
This fall, there have already been nights with several stations on, from XNS just above 137.781, to VO1NA at or just below 137.777. Along with MP, when you find XNS, XGJ, and XKO, they are likely to be in QRSS modes (though I believe they are all capable of others); and you'll likely find XES and NA (short form of VO1NA) running DFCW at 30 or 60 second rate.
73 Rat Shak RS232 capable Multi Meter Sale
John
Posted by Lee on October 30, 2011 at 18:20:29.
Heads up that I picked up localy on sale the Rat Shak RS232 capable meter that comes with software. Got it for 49.95. Normaly 69.95. Don't know if it's a nation wide sale or just a local manager special. But for 49.95 very cool and lots features including computer logging. beacon heard at 513kHz
Lee
Posted by James s. on October 30, 2011 at 21:58:01.
I am new to listening to all sorts of signals. I found this website and want to know what it is I am hearing at 513kHz. It sounds like a beacon or morse code or something. I can only hear it if my dinky little telescopic antenna is pointing north on my little grundig radio. The tone has period off time of about 5-7 seconds. Just curious, because here in Kansas it's all I've heard on the the longwave band. However, on the shortwave bands I've heard radio China out of Bejing as well as radio Habana Cuba. Could someone tell me if they've heard this beacon and if so where does it originate from?
Re: Rat Shak RS232 capable Multi Meter Sale
Posted by John Davis on October 30, 2011 at 23:59:42.
In reply to Rat Shak RS232 capable Multi Meter Sale posted by Lee on October 30, 2011
Thanks for that info, Lee. Given the original price, it sounds like the same one I bought early this spring because my older, smaller DMM wasn't enough any more. I don't use the computer logging, but all the other features of the meter have proven very useful in my projects this year! It was an excellent investment at the original price, and sounds like a real bargain at the sale price.
John
Re: beacon heard at 513kHz
Posted by Barry on October 31, 2011 at 01:33:44.
In reply to beacon heard at 513kHz posted by James s. on October 30, 2011
Could be:
512 kHz HMY-Lexington, OK
515 kHz PN-Ponca City, OK
-Barry
Re: beacon heard at 513kHz
Posted by John Davis on October 31, 2011 at 09:11:16.
In reply to Re: beacon heard at 513kHz posted by Barry on October 31, 2011
It would be helpful to know where you live in Kansas (big place!) to determine the most likely aeronautical beacon. If your location is toward the southern end, Barry's list could be right. If you live in the northeast corner, it might be 'OF' on 510 kHz from Norfolk, NE, or 'PP' on 513 from Omaha. (In southeast Kansas, I hear both of these plus the ones Barry mentioned, almost every day. However, that's with a little fancier receiver and a 40-foot antenna in a quiet location.)
While not all of these beacons are right on 513, the receiver you are using has wide enough tuning that any of these we've mentioned might show up at that location on the dial. The best way to tell for sure which one it is, of course, would be to copy down the Morse code bit by bit and see what the identifier actually is.
John HiFer antenna for SWL report
Posted by Paul on October 31, 2011 at 13:21:21.
Hi gang.
Doing some work at the site where my HiFer beacon is located, and for fun tried hooking the HiFer antenna to the Grundig YB400 SW receiver and dialing around. Very disappointing.
The antenna tunes 1:1 at 13.565 MHz., and was expecting it to really work well as a 22m receive antenna. That was an incorrect assumption. The noise level wasn't that bad, but just a disappointing lack of signals.
Was able to hear WWV on 5, 10, 15, and 20 MHz. easily. No other HiFers.
73,
potrzebie