> Just for kicks, try this with an old analog radio. It would be very
rare for it to have broadband noise because it has no synthesizer.
Actually it can't have any, but maybe there is a way that I am >unaware
of, so I'll just call it rare.
I'd find it interesting to know what the measurements for transmit noise
are for older style radios. I suppose there would be about three types
of transmitters to consider:
1) Crystal oscillator, multiplier, power amplifier rigs.
2) VFO, multiplier, PA.
3) Transmitters using an IF, with heterodyne conversions using a VFO and
crystal oscillators to get to the output frequency.
My guess is that all of these configurations have very little wideband
noise or phase noise. Any of them could have key clicks, which could be
fixed with the right envelope shaping components. Any of them could have
excessive harmonics, and the heterodyne conversion style could have
various spurs from undesired mixes and images in the heterodyne
conversion process. Any of them could mess up a whole band when
operating in phone modes with the mic gain too high. Overall I would
guess that every one of these old style rigs would have less "in the
same ham band noise" than most new rigs. Thess kinds of measurements
were seldom if ever made in product reviews back when those rigs were
being manufactured. I wonder if some well equipped radio lab has
collected any of this kind of data?
DE N6KB
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