Date: Tue, 25 Apr 2017 10:55:15 -0500
From: "Gary Schafer" <garyschafer@largeriver.net>
To: "'Thomas Walsh'" <w2co@comcast.net>, <amps@contesting.com>
Subject: Re: [Amps] Price per Watt Conversation
Not necessarily.
When an exciter with IMD is connected to an amp that produces IMD there can
be a sum or difference of the two levels of up to 6 dB of the IM levels.
So it is possible that the overall IMD level can be less.
This summation is for equal levels of IMD produced by the amp and exciter.
Worst case is up to 6dB greater overall IMD and best case is 6dB better
overall IMD.
73
Gary K4FMX
## agreed. At least thats what the experts at collins say.
Some xcvrs have bad overshoot, some dont. My fix for that
is just to use a 9 vdc battery across the ends of a 100K pot. Then
the wiper goes to the alc input on the xcvr. Positive of battery goes to
xcvr chassis. 0 to –6 vdc is all you require to control most xcvrs.
Then you can dial up how much alc voltage you want.
You dont have to wait to develop alc voltage internally, or from an amp. Its
now fixed..and sitting there all the time.
## set the po for say 85 watts...then scream all you want, with all knobs to
the
right and it will never exceed 85 watts...or what ever level you set it for.
Problem solved. NO spikes or overshoots ever...plus precise power output
control. 9V / 100k = .00009 amps...which is dick. 90 microamps.
Battery will last forever. Simple and effective fix. Put a spst switch in
series
with the battery, and shut the battery off, when not in use.
## Most 100 w xcvrs have so-so imd, when run at 100w. back it off to 85w,
and imd improves a bunch. Back it down to 50 watts, and imd improves a bunch
more.
A 100w K3 has min IMD when run at 30 w output. They all have a sweet spot
for min
IMD. Same deal with a 200w xcvr. When run at 100-150w, imd greatly improves.
Jim VE7RF
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