Re: LF: TA CW?

["Alan Melia" <alan.melia@btinternet.com>]

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

To: rsgb_lf_group@blacksheep.org

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: Stefan.Schaefer@iup.uni-heidelberg.de
To: rsgb_lf_group@blacksheep.org
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