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RE: LF: TA CW?

To: "[email protected]" <[email protected]>
Subject: RE: LF: TA CW?
From: Bob Raide <[email protected]>
Date: Wed, 25 Sep 2013 13:08:45 -0400
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Alan;
You most certainly got me thinking.  I am located on the side of a mile long drop to the East about a 1/4 mile down from the top on the east side of the hill.  Over 1/2 mile remains to the bottom where it is in the village.  I have one small tree near me but nothing really around the self  supporting tower that is 90'.  The two 150' legs are about 35' off ground at the ends.  What I do have is my water well 20' from the tower.  It is a large vein of water that flows from the top of the hill down to the bottom and probably into Keuka Lake.  I never thought about connecting to the well casing as it is about 30' drop to the water.  The water is hard as hell and am sure a good conductor.  I am going to strap a chicken wire radial rite to it today and will be on tonite again for any signs on Gary's  [G4WGT] 72.4 QRSS 500 grabber. 
One problem is that I use this open wire feed ant for 80 and 160 as well as a vertical on 500, 137, and now 72.4.  I just fired up an hour ago and took an ant current measurement and optimized the tuning of the PA.  I will be interested to see if anything changes upon well casing connection.
It is interesting that only 4-5 miles NE of here is the NE Headquartered Loran C 700' tower and 1000KW defunct transmitter, etc.  It is still there but Obama shut them all down to save a few bucks.  It is at the Seneca Army Depot and between Seneca and Cayuga Lakes.  The ground conductivity near all the finger lakes is the highest in the state.  It may have been placed there for the 100 kHz operation purposely[???}
Bob
 

From: [email protected]
To: [email protected]
Date: Wed, 25 Sep 2013 11:22:27 +0100
Subject: Re: LF: TA CW?

Hi Bob that sounds a good set-up. Excuse my "telling Grandma how to suck eggs" (as we call it) in my last, but I have seen many frustrated LF ops after much work and investment in copper, gain little in ERP :-)) It is all a matter of your local conditions.
 
Yes the 150' runs of your dipole will make substantial capacitive top load (~600pF) but I guess they droop, as in an inverted "V"?? Paralleled wires help, provided they are spaced more than about 3 feet apart, current direction is unimporant as they are not radiating. There are some interesting measurements on a small antenna at http://g3nyk.ham-radio-op.net/spiraltop.htm. It was a little impractical because of the windage :-)) but an interesting experiment, that was stimulated by an article in a Canadian Broadcast Engineering journal.  (I hope all the links work....I have had some troubles with them)
 
Laurie G3AQC found the the more top capacity he could add the lower his ground loss became and he finished with a meander that gave around 1500pF I believe......at 6pF per metre you can see what that means in length. By measurement we found that once the ground loss ceased to decrease by adding extra rods and wire.....doubling the top capacity would further half the ground loss. The catch was the top-load needed to be over "clear ground" not foliage (he had a bank of Rhododendrons in his garden, and had to avoid going over those, or any roofs) The commercial stations use umbrella loading (CFH Halifax NS) or enormous "fans" at NAA Cutler Ma. The classic GBR Rugby "figure of eight" was filled-in in later years to increase the capacity of the 16kHz antenna. This effect does seem to lie unappreciated by a lot of ops but many can't use it because of lossy trees and buildings in the region of their antenna.
 
Of course as you will be well aware at these power levels insulator loss, and corona starts to be a major concern. I think Warren has set fire to several lengths of plastic water pipe used as insulators and spreaders :-))  
 
Best wishes. I am sure that if you make the West to East  crossing on 73kHz you will be the first to do it in that direction.
 
Alan
G3NYK   
----- Original Message -----
From: Bob Raide
Sent: Wednesday, September 25, 2013 2:01 AM
Subject: RE: LF: TA CW?

Alan;
I appreciate your input on 73.  It was my idea to have Warren Zeigler file an app just to see what might happen at our FCC.  I had heard the staff at our FCC was instructed to welcome experimenters for the lower freqs.  Warren filed it but told me nothing may come of it but they granted us the license!
I am using a tube amp [3cx3000A7] with pi-net output and can make 2 kw easily.  But only have a 90' high tower and at the top is the center feed point of my 75 meter double extended zepp.  I simply short the open wire line which runs almost vertically and fed it with allot of inductance in series! I assume the two 150' legs acts as top loading. Ground system is from my broadcast experience where for field intensity surveys 36" wide chicken wire was used with a 100' tower most often and a 250 transmitter.  Eight 50' chicken wire radials produced decent field on the midband channels [1000 kHz or so] to measure from.  Here I am using several 150' radials of chicken wire radials.  I hope to stretch some out to 300' but that's going to be about it at my location.  I have made it out to Kansas just two days ago with solid QRSS 60 sigs daytime. 
I am running just about 1.5 KW into the ant.  The voltage at the feedpoint draws over a 2" spark to a screw driver so am about at the power top end I think.
Here in the finger lakes region of NY State the winter ground conductivity goes to 8 or better to the NE with several finger lakes East of me.  If I were on the coast I think it would be a snap to hit the UK over the salt water.  Going to be harder for me inland here.
Any comments would be appreciated-Bob

From: [email protected]
To: [email protected]
Date: Wed, 25 Sep 2013 01:16:12 +0100
Subject: Re: LF: TA CW?

Hi Bob, the propagation conditions are very similar to the other LF bands ....there is skywave but the ground wave is stronger further. The usual problem is antenna efficiency .....in rounded figures 73 is 4 times more difficult than 136, which is 10 times more difficult than 470/500.
 
Beware of using HF or commercial "folklaw" on ground systems You MUST measure as you go otherwise you will waste a lot of time and dollars to no great effect. I measured Ground Loss in experiments with Finbar early in the 137 era (using a simple transformer-ratio-arm-bridge), and rolling out "radials" can be a big mistake.....it all depends on your environment. the first one or maybe two make a difference then it gets you wont notice the difference To be effective radials on amateur sizes antennas need to be at least 1/8 wavelength which is over half a mile! Unlike 160m skin depth in the ground can be 30 feet or more at these frequencies. A lookat commercial VLF antennas is more helpful. They use massive capacity top loading, but they can usually choose their site for its suitability.
 
The only station to make the crossing on 73 when we still had it on this side was Laurie G3AQC (now SK) He was using 1200W from an ex Decca Nav TX and a reasonably efficient antenna...... but not that good.His ERP was probably close to 1watt.
 
Best of Luck .....   its a pity we will not get an allocation there again.
Alan
G3NYK (an original UK 73kHz "licence" holder)
----- Original Message -----
From: Bob Raide
Sent: Wednesday, September 25, 2013 12:01 AM
Subject: RE: LF: TA CW?

Stefan;
73 kHz band is going to be difficult from my preliminary tests.  Seems to be a lack of skywave.  I think skywave is going to be rather scarce and best I am doing so far is out to Kansas but it is ground wave am sure.  Got to get the ground system rolled out here soon as lawn mowing ends.  That should help to give me more field strength on all the bands.  Going to try 73 periodically and see what shakes out!
I have worked PA0A on CW by ear last winter on 500.  Yes our 500 licenses go down to 470 region.  In winter we should have no trouble working CW by ear am sure and will be looking forward to it as you would be even further away from me than PA.  I also worked into N. Ireland and I went to SSB and was heard and worked Finbar, EI0CL [I forgot the suffix of his call] cross mode as he has no SSB authorization.  Jay, Warren and I work regularly Sunday evenings on 510 upper throughout the Winter months.
I see no takers for 73.  Gary has a grabber on 73 for us and using QRSS 500 spec lab and I tried last nite but never saw a trace.  With ground system out this Winter his grabber may be a winner-Bob
 

Date: Wed, 25 Sep 2013 00:36:21 +0200
From: [email protected]
To: [email protected]
Subject: LF: TA CW?

Hi Bob,

Success! :-) Welcome! :-)

Sorry i can't receive on 4000m here since my receivers are mono band homemade DC converters (for 137 kHz and 472 kHz) and direct sampling receivers at 0...24 kHz.

But, i remember you were the strongest station on MF (is that 472...479 kHz for your licence?) last season. Are you a CW man as well? Do you think it is realistic to try for a TA CW QSO? If, then it could work in november to february. So far i'm only getting sporadic WSPR-2 decodes at WD2XSH/17. My WSPR signal is QRP though. At least VO1NA copied my signal in GN37OR last year...
Worth a try? I'm continuously doing overnite WSPR-2 tests on 630m.

73, Stefan/DK7FC


Am 24.09.2013 23:45, schrieb Bob Raide:
All;
With Stefan's help I seem to have finally made it into the group.  I am Bob Raide W2ZM with exp.  license's for 500, 137, and most recently 73 kHz band.
I am ready to fire up on 72.401 with Qrss 60 if anyone is interested to try for a capture tonite.  Or I can change to 137 if no one is interested in 4000 meters.
500 kHz call-WE2XGR/6, 137-WE2XEB, 73-WG2XRS/4
Thanks all, Bob
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