Too many diversions Dave with others bridges, gdo's etc. Keep it simple and
keep everything 50 or 70 ohms and that way it is easy to match tx impedance
to antenna. Avoid articles in comics !!
G3KEV
----- Original Message -----
From: "Dave Sergeant" <[email protected]>
To: <[email protected]>
Sent: Tuesday, May 22, 2007 12:33 PM
Subject: Re: LF: 500kHz Distance
> 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
>
>
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