>>
>>Why not use a storage spectrum analyzer to look at occupied bandwidth
>and
>>IM over a significant time period while modulating with speech or
>pulsed
>>white noise? Wouldn't that be a better worst-case test?
>>
>RE: pulsed noise: Only if the pulses are spaced far enough apart to
>cause the screen potential to decay to near zero volts between pulses.
Implied in my question, but not expressed, sorry. Broadcasters sometimes
use pulsed noise as a substitute test signal for "program audio". It's
handy for occupied BW and other measurements. The pulsing is an
important part of it all, since xmtrs bounce and overshoot with
modulation sometimes causing carrier shift and thereby IMD... (You don't
need a carrier there for the IM to happen). Anything that wiggles the
screen V will wiggle the output and that may cause IM. At least, so it
would seem...
>RE: speech modulation: I have listened with stereo headphones using
>two
>double-filter receivers. The total IMD in the window above or below
>the
>DAF amps. was no better than 23db down.
I guess for mere mortals in the real world without spectrum analyzers
that's a pretty good test! Just a little difficult to quantify and
duplicate. It ought to be simple to test this design on the bench with
modern test gear and settle this pretty quick. Has anyone done this?
(Not discounting your 2 rcvr tests here.)
> However, this is perfectly
>legal
>as long as the rotten splatter does not go outside of the ham band.
>- - There ain't no such thing as a 200mpg carburetor for a 1969
>Dodge
>V8.
It sure seems intuitive that screen V needs to be fairly constant, but
I've been surprised before.
73 Rich,
Gary
--------------------------------------
- W3AM - Gary Blau -
- w3am@juno.com -
- http://www.w3am.com -
--------------------------------------
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