|[AMRadio] hamfest oscopes|
brett.gazdzinski at verizonbusiness.com
Thu Dec 28 10:42:26 EST 2006
I have never done the trapezoid thing.
I do the modulated waveform thing off the receiver IF.
You often have to play with things to get the correct
amplitude on TX without RX overload, but that allows
me to look at others modulation on receive.
The R390 does this real well.
On the homebrew receivers, I just run a small cap
and resistor off the IF.
I can clearly see under and overmod, positive peaks,
closing off the carrier, it does not burn the crt,
is much more interesting to watch, and is easy to do.
The trapezoid would give more clues about transmitter
distortion I suppose.
Since most IF frequencies are around 455Khz, almost
any scope will do well.
No probes off HV points, or rf pickups to radiate
into things in the shack...
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