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Re: LF: 500 EASY START

To: [email protected]
Subject: Re: LF: 500 EASY START
From: Alan Ibbetson <[email protected]>
Date: Mon, 23 Apr 2007 23:03:25 +0100
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Hello everyone, Alan G3XAQ here. I just joined this mailing list. I'm preparing my application for a 501KHz NoV, so Mal's note on an easy start is very timely.
For me, there is an even easier route to getting on 600m in that I
already have a 3 stage transmitter with plug in coils. The only problem
is I will need a fundamental crystal somewhere in the band. Quartslab
don't seem to do LF crystals. Does anyone know of a supplier?
Is there an archive anywhere of the aerials folks are using? I'm
thinking of pressing my 15m high 160m inverted-L into service. The
vertical section runs quite close to my tower and I was wondering if
it's worth end loading the wire with a coil, part way along the
horizontal section, just to get the high voltages away from the tower? I
know that going from triangular to uniform current distribution (below
the coil) will raise the radiation resistance 4 times, but since we are
being licensed on ERP this just means I will need half the aerial
current. My motivation is tower coupling loss minimisation, seeing as I
can't measure it, not absolute efficiency. Mind you, all this ERP stuff
seems a bit bonkers and quite unlike the usual ham licensing approach.
Who can measure ERP with any accuracy? Why not just give us the usual
stipulation of tx power at the feedpoint and leave it to all of us to
make the most efficient aerials we can?
What is de rigeur for the receive aerial? Does everyone use the transmit
aerial, or should I be thinking about a medium wave DXer's tuned loop?
Sorry for the dumb questions. There doesn't seem to be much on the web
that is useful for amateur sized gardens. My Services Textbook of Radio
vol 5 suggests that for MF I should begin by erecting a 100m tower...
I hope to get the NoV application off by the weekend. See you all on the
band soon.
Alan G3XAQ

In message <[email protected]>, hamilton mal <[email protected]> writes
Hi All
An Easy Start solution for 500 is to use an existing HF rig modified for 5
mhz tx at low power, then shape the sine wave to sq wave  with a single chip
and divide by 10 with another chip then a driver chip to a fet pa, then lpf
and you are in business. A single fet class E pa is sure fire and so simple
to build. Mine went first time.
My solution for an exciter is an IC 706 on 5 mhz and also used on 13.7 mhz
for LF used. This is a vy stable sig source.
If anyone needs more info about type of chips etc let me know.
73 de Mal/G3KEV



--

Cheers,

Alan G3XAQ
[email protected]



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