[AMPS] Receiver tests in the past........

[Tom Rauch]

> Tom, go wash your mouth out! You're not supposed to ask awkward questions
> like that! Generally, the close in (2kHz) IMD specs are set by in channel
> IMD requirements, where AGC is supposed to prevent overload. (Ripple from
> the demodulated envelope on the AGC line is another matter, and often
> screws things up - one answer is a phase compenstaed active LPF with a cut

That's fine for SSB or digital modes.

> off around 50 - 100Hz in the AGC path) These awkward people who use CW and
> are thus interested in real IMD from signals out of passband are generally
> ignored - not enough commercial demand. This is where there are advantages
> in older rigs with an IF around 8MHz or whatever, where the first crystal
> filter is a narrow CW filter. But those filters aren't as good on IMD as a
> lower frequency filter, of course. Resurrect 3395, the Heathkit IF?

My Drakes are fine (modified with new mixers, higher injection, and 
new amplifiers) with dual 8-pole 5.6 MHz filters.

BDR is the same at 1000Hz as it is at 10 kHz.
 
> But to repeat - the close in phase noise has got to be good enough to
> allow the good IMD performance to be used.

The PTO in the Drake is as quiet as necessary. I haven't found a 
transmitter yet that is as quiet as the Drake's PTO, so external 
noise is the limit.

Ten Tec's are really low phase noise also, and I plan on hacking 
into a receiver soon.


73, Tom W8JI
w8ji@contesting.com

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