Beacon BRO 182.2 kHz
Just a note that BRO is still off the air pending repairs. I hope to be back on by this fall.
73, USAF Survivable Low Frequency Communications System
Bryce
Posted by Henry M on May 05, 2008 at 10:37:15.
Where were transmitters located of USAF Survivable Low Frequency Communications System? What kind of antennas did they use? test email
Did the USAF Survivable Low Frequency Communications System also use transmission sites outside USA? Are all facilities used for it demolished?
Posted by Andy on May 05, 2008 at 11:55:52.
test email, can't get another message to post.
Re: USAF Survivable Low Frequency Communications System
Posted by John Davis on May 05, 2008 at 23:10:48.
In reply to USAF Survivable Low Frequency Communications System posted by Henry M on May 05, 2008
I'm not familiar with any system by that operational name. Are you refering to the Ground Wave Emergency Network (GWEN) system, by any chance? It was operated by the Air Force, and that sounds like a description of what GWEN was supposed to be/do.
If so, the antennas were heavy duty guyed vertical radiators, about 300 feet tall if I recall correctly, typically using part of the guy system for top loading. I no longer have a complete list of the old facilities, but they were all located within the US. Many of the old sites were turned over to the Coast Guard and have been converted to Differential GPS stations.
Re: VLF-transmitters at Japan and Hawaii
Posted by Paul Tigge on May 07, 2008 at 12:47:40.
In reply to VLF-transmitters at Japan and Hawaii posted by Henry Smith on March 31, 2008
Harald?
Re: USAF Survivable Low Frequency Communications System
Posted by Dex on May 10, 2008 at 17:17:32.
In reply to USAF Survivable Low Frequency Communications System posted by Henry M on May 05, 2008
http://www.airforcebase.net/usaf/GWEN_list.html 1750 Meter CW/SSB Transceiver kit
Posted by Henderson on May 13, 2008 at 12:27:55.
Is there anyone that can tell me where to find a 1750 Meter CW/SSB Transceiver kit. I've tryed the only 2 places I've found on the web but with no luck, or possibly where can I find the schematic and a parts supplier for it, . . . or possibly a working used one for sale? Any help would be most greatful.
Thank-You Re: 1750 Meter CW/SSB Transceiver kit
B.Henderson
Posted by John Andrews, W1TAG on May 13, 2008 at 18:30:38.
In reply to 1750 Meter CW/SSB Transceiver kit posted by Henderson on May 13, 2008
Here's a message that was posted recently on the QTH.net Lowfer reflector:
You might try contacting Dave Curry, WD4PLI/PLI at: davecurry [at] charter [dot] net
Dave has been working on designs for 1750 meter transceivers and also higher power Part 5 beacons with the idea of helping people just like you get on the band. He's active on SSB here in the LA area but at the moment there's only one other active SSB station - ELU in Simi Valley. Dave used to try to sell kits but found it was too much work about the time that he finished college, got married, bought a home, and started working full time for the LA City Police Department which turns out to do a lot of electronic design and manufacturing. He's also very active in church work and in music but has a keen interest in getting more people on the air. Long ago he lived in NC and considered Todd Roberts as his mentor.
Ed Phillips
Re: 1750 Meter CW/SSB Transceiver kit
Posted by Henderson on May 14, 2008 at 05:52:17.
In reply to Re: 1750 Meter CW/SSB Transceiver kit posted by John Andrews, W1TAG on May 13, 2008
I've tried this address http://www.davecurry@charter.net and it gives me a ( The page cannot be displayed )
I've been trying to find other places to find a kit simalar to that one, but with no luck at all. I've found the LowFer Receiver, and the Simple LowFer Transmitter schematics, but they cover only 1 small piece of the band.
So I guess I'll try to keep looking, any more help is greatly apreaciated.
Thank-You Re: 1750 Meter CW/SSB Transceiver kit
B.Henderson
Posted by John Andrews, W1TAG on May 14, 2008 at 07:12:38.
In reply to Re: 1750 Meter CW/SSB Transceiver kit posted by Henderson on May 14, 2008
That's an email address, not a web site.
John A.
Reception of " MP " in Friendsville, Tn.
Posted by Andy - KU4XR on May 21, 2008 at 11:05:13.
Hello Everybody, and greetings from the Southland; Hope you're all having fun LOWfer-ing around.I'm still trying to dig out signals. Managed to get " MP " in EN93ja, London, Ont. CA.Mitches little LOWfer powerhouse punched through again at least twice through the night.making the 526 airmile trip here into Friendsville, Tn. - EM75xr.The Unfiltered Static level here was 15 to 20dB over S-9. With my rigs 480Hz filter, it was still a constant S-7 to S-9 level, but my 80Hz audio filter, and Spectrum Labs DSP filter set at 5Hz BW, can make a gnat passing gas sound like an atomic bomb explosion. ( LOL ). If all goes well; I'm going to try to dig out " EAR " tonight and see what shows up. Re: USAF Survivable Low Frequency Communications System
73, from Andy Bell - KU4XR - EM75xr
Posted by Steve on May 21, 2008 at 17:23:24.
In reply to USAF Survivable Low Frequency Communications System posted by Henry M on May 05, 2008
Hi Henry -
To the best of my knowledge, there were only 3 transmitters for the SLFCS net (btw SLFCS is not GWEN - similar mission, different systems):
Hawes Field, CA 34°55'2.46"N 117°22'36.59"W
Silver Creek, NE 41°20'46.00"N 97°43'18.18"W
and Looking Glass SAC Airborne Command Post.
Both fixed sites were demolished per treaty agreements.
Some internet sites:
http://members.tripod.com/airfields_freeman/CA/Airfields_CA_PalmdaleN.htm (about 2/3 down)
http://www.militaryphotos.net/forums/showthread.php?t=124090&page=2
Hope this helps - Steve KC0YA
Online view of screen capture
Posted by Andy - KU4XR on May 22, 2008 at 21:10:59.
In reply to Reception of " MP " in Friendsville, Tn. posted by Andy - KU4XR on May 21, 2008
I now have Webspace available with my current ISP and plan to upload some of the captures I have received. This one can be seen at http://webpages.charter.net/ku4xr.
TAG WOLF 185.800
Posted by John Andrews, W1TAG on May 24, 2008 at 16:57:12.
Lowfer TAG in Raymond, Maine (FN43sv), is back on the air in WOLF(10) mode on 185.800 kHz. Reports are always welcome.
John Andrews, W1TAG
A few screen captures now online
Posted by Andy - KU4XR on May 27, 2008 at 18:39:52.
Hello everyone: I have uploaded some of my screen captures from this past season and some other information that might be useful to a few. Have a look if you wish; thw site is http://webpages.charter.net/ku4xr 73, to all: radio restoration
Andy - KU4XR
Posted by dave sampson on May 28, 2008 at 10:27:37.
hello
am restoring an 1p 501A receiver. Vertical Antenna Questions
am in need of quite a few impossible to find parts.
would like to know if anyone could help?
thanks very much
dave
Posted by Andy - KU4XR on May 29, 2008 at 08:17:10.
Hello Fellow LOWfers:
I would appreciate any experienced input on some vertical antenna issues
for 1750 meters. " Using a vertical wire with top hat "; which would radiate better; a shorter vertical with longer top hat, or longer vertical with shorter top hat ?? I would assume that the more wires you can include in the top hat, the better the RF will reach the top and radiate. Is this assumption correct or not ?? Has anyone tried hellically winding a section,say 20 feet ( bottom , middle , top section ) so the overall heigth would bea more one man manageable 30 feet ??. A realistic and do-able antenna for mewould be a 20 foot vertical with a 30 foot top hat which can include many wiresin different directions ( a capacitance issue only I'm sure ). Would ground losses be more evident with a top hat version, or the straight vertical ? Any input will be valued and appreciated:
73, from Andy Bell - KU4XR - EM75xr Re: Vertical Antenna Questions (long)
Posted by John Davis on May 29, 2008 at 22:09:10.
In reply to Vertical Antenna Questions posted by Andy - KU4XR on May 29, 2008
"Would ground losses be more evident with a top hat version, or the straight vertical?"
Ground loss is always more significant on an electrically short vertical if there is no top loading.
First, consider a short vertical radiator working against ground. There is maximum current in the bottom of the radiator, some of it continuing on up the antenna but much of it finding its way to ground at a relatively low height; less in the middle; and falling off to none at all at the very tip, essentially because it has nowhere to go. In an electrically short vertical (significantly less than an eighth of a wavelength) the current distribution in the wire falls off at an essentially linear rate.
Now, a conductor radiates RF according to how much current is flowing in the same direction in each successive unit length of the wire. More current means more radiation, as does a longer conductor length carrying that same amount of current. Combined with what we've already said about current distribution in a short vertical, that means most of your radiation will be coming from the bottom few feet of the antenna (where, unfortunately, it stands a high chance of encountering lossy items in its vicinity), and none at all from the very top of the antenna.
Given linear current distribution, from maximum at the bottom to zero at the top, the AVERAGE current in the whole radiator, end to end, is just HALF of the current at the feedpoint itself.
Another way of looking at that is via a concept called "effective height," which has an additional advantage over thinking of just how the averages out. Since radiation of an electrically short vertical is essentially just the product of current and the length of the conductor in which it flows, you can imagine the current being uniform over the whole antenna and try to find the length of the imaginary uniform radiator which would give the same (reduced) signal as the real antenna carrying half the averaged current. An electrically short, unloaded vertical... under absolutely ideal conditions... therefore has an effective height of only half its actual physical height.
I hope that isn't too convoluted to follow, because it relates directly to loss and efficiency.
Continuing on: we know, through a century and a quarter of detailed experiments, that the radiation resistance of a short vertical--that part of its total impedance resulting from RF power actually wafting out into space--is proportional to the SQUARE of its length in relation to a wavelength. If you could double the height of the radiator, you would actually quadruple the radiation resistance. If all your ground and other losses, that'd mean you could radiate four times the power at the same level of current into the base of the antenna.
This is as true of effective height as it is physical height. If you can't actually increase a radiator's physical height beyond a certain point, you need to find a way to increase its _effective_ height instead.
Since the current distribution (most at the very bottom, none at the top) is what limits the short vertical's effective height to half of the physical height, then what you need is a way to ensure the current at the top of the vertical run is NOT zero. That means providing a way for current to flow out of that top point of the radiator, yet not in a direction that's going to oppose the phase of the radiated energy. Voila! Add a *horizontal* top load, consisting of anything from a single wire, to multiple wires, to a solid disk. Then the current has somewhere else to go on its way back to the ground system, and doesn't dip to zero by the time it reaches the tip of the vertical run.
The more effective you are at making current at the top of the vertical section nearly equal to the current at the feed point, the closer you come to making it radiate equally well from bottom to top...and therefore you effectively bring the effective height up closer to the physical height, and bring the radiation resistance up by the square of the effective height, making it much greater in comparison to ground losses as well.
The Navy's biggest VLF rigs use multiple vertical runs of several hundred feet to over a thousand in height... still very miniscule when talking wavelngths on the order of miles... combined with literally thousands of feet of toploading that overshadows the towers themselves. Not only does this greatly improve the effective height of the radiating masts to nearly 100% of their physical dimensions, but it also spreads out the displacement currents over a greater area of ground. By keeping current concentrations low in any given volume of soil, distributing the ground currents that way minimizes resistive loss in the earth.
Of course, the Navy is not limited in the size of their tophats by anything but budget. In Part 15 LowFERing, 15 meters total length includes _everything_ combined.
Obviously, there is a tradeoff when your total length of antenna is arbitrarily limited. If you put most of your length into the horizontal run, you can get a very uniform current in what little is left of the vertical run...but it won't do much good, as radiation is the product of current times the LENGTH of path over which the charge carriers in the wire or mast are being accelerated.
On the other hand, too much vertical and too little horizontal run means you're not getting all the current uniformity that you could otherwise achieve.
(And remember, only the VERTICALLY polarized radiation counts in this. If you have a symmetrical top load like the horizontal run of a T antenna, or a disk-shaped top load, the currents in each horizontal section of conductor have an equal counterpart flowing in the opposite direction on the other side of the top load. Their radiated waves cancel each other out; a symmetrical tophat does not radiate at all horizontally. An asymmetrical one like the top of an inverted-L will radiate in the horizontal plane, but the wave's reflection from the ground comes back with the opposing phase and cancels most of the horizontally polarized energy. Hence, only the vertical component really counts for what we're trying to do.)
As for optimum ratio of vertical section to top hat: Some years ago, Mike Mideke and a couple of other experimenters tested a variety of vertical antenna configurations for Part 15 use, and found that in general, the optimal tradeoff between vertical and horizontal sections was to have two-thirds or a little less of the permissible length in the vertical plane, and use the remainder for top loading.
In today's metric limit on 1750m Part 15 length, that works out to about 10 meters vertical and 5 meters horizontal.
Those are the basic highlights of plain verticals with top loading. Two other loading approaches have been tried with varying degrees of success too.
One of them is to elevate some or all of the loading coil, so that only the top of the vertical section is above the coil. Half to two-thirds of the height seems about right. This also increases effective height, and by placing the highest voltage portion of the antenna well above ground, seems to make it less susceptible to environmental losses and detuning as well. The drawbacks include the physical awkwardness of breaking up a mast to insert the coil, and the problem for strict-constructionist rule interpretation that the length of wire in the loading coil then becomes part of the antenna, not a component in the transmitter itself.
At least one member tried continuous helical loading 15 or 20 years back, with the helix wound on PVC pipe. Unless you use some sort of tophat with this arrangement, though, it's very hard to get anything other than the linear / triangular current distribution (and resulting 50% effective height) anyway. It just seems to be a fact of life when antennas are only a percent or so of a wavelength. A helical with no top hat also seems very touchy to tune in this band. And again, there's the question of counting the wire in the winding of the helix against the height limit.
I know that's a lot to absorb, but assimilate what you can and feel free to ask further questions at any time.
Re: Reception of " MP " in Friendsville, Tn.
Posted by KG4ENB on May 30, 2008 at 20:07:43.
In reply to Reception of " MP " in Friendsville, Tn. posted by Andy - KU4XR on May 21, 2008
Hello Andy,
My name is Bryan (KG4ENB) and I live in Maryville. I think it is really neat that there is another person This close that is also intrested In lf. Just thought I would say hello.
Re: Vertical Antenna Questions (long)
Posted by Peter B on May 31, 2008 at 06:12:14.
In reply to Re: Vertical Antenna Questions (long) posted by John Davis on May 29, 2008
Andy and John,
Might I add that what John described is actually a hip-pocket recipe for constructing an effective vertical as I have become fimilar and understand it. This account could be amplified upon to form a primer for newbies all. Why? Because of it's brevity and practicality, esp. appling to Part-15 LowFER pursuits.
The only part that I choked on was the para. before "I hope that isn't too convoluted to follow." Ha, it WAS just that and I suspect the author did also. Unfortunately, placed near the beginning of the work it likely caused some to not finish reading. That's my grammatical criticism of the work: rework those thoughts, John.
New to me was the info on Medeke's work on the V:H ratios for Part-15. Makes sense, as does elevating the loading coil.
Hope John's piece helps Andy and others. If any hazy thoughts remain, please raise them now.
Cheers -- Peter
potrzebie