W4WRL wrote:
>
>can anyone tell me where i might find infomation on
>a high pre-amp i can build for 2 meters and 432,
>somethink that will stand a few hundred watts through
>it?
>thanks in advance for any help you may offer.
The most helpful word I can think of is: don't!
At that power level, sequencing problems are critical in order to avoid
hot-switching, resulting in blown GaAsFETs and damage to the coax
relays. Using a separate RX feedline down from the preamp is much
simpler, uses fewer QRO coax relays, and is vastly more reliable.
Depending on the length of line and the frequency, RG-213 or 9913 should
be fine for the RX line.
There's a simple sequencer circuit on my web site, using two DPDT relays
to control the coax relays and PTT/power.
If you energize the relays on receive, you have a fail-safe system that
leaves the preamp off-line when the station is powered down. If the
preamp does fail, it also allows you to continue receiving through your
low-loss TX feedline.
73 from Ian G3SEK Editor, 'The VHF/UHF DX Book'
'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.demon.co.uk/g3sek
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