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From: "Dave Sergeant" <dave@davesergeant.com>
To: rsgb_lf_group@blacksheep.org
Date: Tue, 22 May 2007 13:33:16 +0100
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Subject: Re: LF: 500kHz Distance
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Interesting comments...

I agree that specifying power in terms of ERP is not really that 
suitable for amateur operation and a licence specified as power 
output, as per all the usual amateur bands, is far more sensible.

At G3YMC I have been having great fun getting going on 500kHz. 
Building the TX was the first bit of fun, a pretty simple affair but 
it took me rather longer than the 15 minutes Mal is suggesting. I 
suspect very few of us could build anything electronic from scratch 
in that sort of time (even from a kit...). Trying to match it to the 
antenna was the next bit of fun, and I spent time recalibrating my 
noise bridge, building a different impedance bridge, another look at 
G3LDO's 3M bridge and then playing with Reg G4FPQ's programs to 
explore what was really at the end of the coax. Oh, there was also 
that small job of digging out the long disused variometer (thanks 
GW4ALG), retensioning its wire, connecting it at the base of the 
antenna, then trying to find the resonance point. All good fun and 
part of amateur experimentation.

At the moment I have had 1.5 QSOs and a few local listener reports. 
My experiments tell me why my signal is pretty weak - my ground 
losses are over 300 ohms! I actually knew that already from both 160m 
and 136 experience. I could of course just build a bigger PA (100W 
would be getting there I guess...). I plan to follow the alternative 
path - work on getting the earth losses down to a sensible level. 
500kHz has given me the incentive to persue that path, which will not 
only get me more QSOs on that band but also next season you may well 
see me working W stations on Top Band on QRP as a result.

Next step is to make my noise bridge and impedance meters portable so 
I can measure what the ground loss really is and to easily measure 
the difference improvements make. See me on the band in due course...

73 Dave G3YMC


http://www.davesergeant.com