> "Gary" <[EMAIL PROTECTED]> wrote:
> About a year and a half ago I replaced the whole board
> on my VHF MSR2000 110 watt NCD PA. (My PA had more
> problems than just the transistors) I used the PA board
> out of a 110 watt mitrek mobile.
Tis' the cost effective way if you have the skills,
proper tools, bright lights, decafe coffee and knowledge..
> It took me an afternoon to do it as I recall. I had to
> remove the power control circuitry and change some
> values of some resistors on the input side of the mobile
> PA, but it still works great today with a nice clean output.
The time required seriously depends on the model and
band of operation. Double the time when dealing with the
UHF ceramic substrates.
> MSR2000 PA's are notorius for failing, especially the
> NCD units.
What is an "NCD unit"?
> You could not back the power down enough and still
> maintain a clean output, no matter how much air you
> blew on and out of the PA.
..?
Power reduction is simply done with the pot, if you
require less than the control circuit will handle,
simply bypass the final stage. Most RF amplifiers
work better at the nominal operational values.
> The CD units faired a little better, but those
> darn ham operators could fry
> them too! Ha! Ha!
> Gary KB7TRP
Only the Micor style msr pa's seem to be trouble below
150Mhz. I've never had a 110 watt vhf intermittent duty
cycle pa fail when tuned down to 60 watts. Same with
the high power (semi rare) Paging MSR PA.
The fly in the vhf msr soup is the high split msr
micor style pa. It's not happy below 150Mhz without
serious power reduction (or modification).
cheers,
skipp
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