Date: Mon, 25 May 2015 03:24:46 -0400
From: "Roger (K8RI)" <k8ri@rogerhalstead.com>
To: amps@contesting.com
Subject: Re: [Amps] Real danger to use the ORANGE button
Jim, how far off the frequency were you listening? I may need to do
some experimenting,
120 watts is plenty. A clean signal at 120W is a bonus.
73
Roger (K8RI)
## BE real careful when listening off freq.....with a 2nd xcvr. Its very
easy to goof up
and add the RX BW of the 2nd xcvr to the TX bw of the 1st xcvr.
## IE: put 1st xcvr on LSB..on say 3830 khz..on TX. If 2nd xcvr is tuned to
3833 khz..and LSB is used,
the top end of the 3 khz rx filter will just touch the bottom end of the TX
filter. If on the other hand the 2nd xcvr
is tuned to 3827 khz, the entire rx filter will now extend from 3827 ...down
to 3824 khz.
## For a poor mans spectrum analyzer, the 2nd xcvr can be also used with a
pair of 500 hz cw filters.
In normal practise, I would put the TX xcvr on 3830 LSB...then put the 2nd xcvr
on 3833..then tune higher in freq,
till imd is still heard. Then switch to class A.... and it will vanish. Typ
deal was to TX on the normal 75m ant...
then listen on 2nd xcvr...but with a 6 inch piece of wire stuffed into so-239
for a RX ant. You only want like a
20 over S-9 signal, when listening on 2nd xcvr...when tuned to same freq.
Tune up from there...till you still hear
the higher pitched buckshot.... then toggle xcvr #1..from Class AB..(75w pep
out) to class A...also 75w pep out.
its like apples and oranges.
## beware, on the MK-V at least..when u switch from class A to AB.... you are
also going from 75w pep out,
class A...to 200w pep out, class AB. If you want to compare apples to
apples, the po control has to also be tweaked,
so you are also running 75 w pep out..when in class AB. Try it also with
processor on and off. The processor really
brings up the average level of the TX signal..but it also increases the average
level of the off freq IMD buckshot.
## You can also try other stuff....like put both xcvrs on the same freq....
then toggle 2nd xcvr between LSB and USB.
When I do that listening to my buddys MK-V.. I hear nothing when switching
sidebands. However when listening to
an Icom 756 pro 2/3 I can hear crud on the opposite sideband.
## do all the experiments with the 1.5 kw amp shut off..u just want to test
the xcvr under various condx.
Jim VE7RF
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