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[Amps] Why hasn't solid state replaced tubes?

To: <amps@contesting.com>
Subject: [Amps] Why hasn't solid state replaced tubes?
From: w8ji at contesting.com (Tom Rauch)
Date: Fri Mar 7 12:52:15 2003
> We are not talking about precise measurements here but getting in the
> ball park as to how bad a signal is by an easy method.
>
> Any method that uses voice as a signal source is not going to be very
> precise anyway.

Every test method has some flaws. The key is picking the most meaningful and
least problematic test method.

The rules are pretty simple. We are not allowed to cause harmful keyclick or
splatter interference to adjacent frequencies or to any other system. We are
not allowed to have any modulation related product outside the licensed
frequency range of the control op. There is no actual "dB down" requirement
for modulation products that makes them "legal".

My experience is harmful interference may occur if products are less than
40dB below peak from 1500 watt systems with good antennas. Occasionally
spurious signals 50-60 dB down cause problems. The wider the swath the rig
cuts, the greater the likelihood the rig will bother people. An occasional
spit once every few minutes isn't going to bother much compared to something
happening every second or less, especially if it is over a wide area of the
band. It is a level, bandwidth, and frequency of occurrence problem.

With this in mind, the most important test is one that most closely
indicates if typical modulation under worse case conditions causes
noticeable interference and how far up and down a problem extends. I agree
with Ian and others, the best test would be voice (or normal CW) and we
really must check both above and below. Two-tone is probably the least
important test, but it does indicate that designs are not getting any
better!

I'd hate to see us start thinking a simple "flip sideband" would prove
anything. It's the crap 6-20kHz away that means we have a major problem.

73 Tom

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