"Dummy" wrote in message
om...
I'm having a two-way radio. One wide-band antenna was hooked up on a
spectrum analyzer. Video BW and RES BW was adjusted to 3khz and 1kHz
respectively at spectrum analyzer. Span was 300KHz.

When radio was being keyed up, spurs could be seen at around plus
minus 32Khz and 62khz. However, the amplitude were quite low, about
-65 to 70dBc. I was wondering what caused the spurs to appear. If
radio was connected directly to spectrum analyzer, this problem could
not be seen.

When radio was transmitting to different load with different VSWR (up
to 8:1), no spurs were seen. Spurs could only be observed while using
antenna. Could the VSWR of antenna be worse than 8:1? Just could not
figure out the source of the spurs. Please help.

I'm having a fine day.
There are too many possibilities to decide with this medium. If you are
making these kinds of measurements without an experienced RF Tech or
Engineer you will see many many strange things which defy explanation in
this forum where many assumptions must be made - and we all will make
assumptions based on our experience.


Things to consider:
Location of the antenna - RF could be getting into the radio
- RF could be getting into the Spec Analyzer
Do some radio or antenna moving or even some hand waving to see if a RF
field is a contributor.
Get the analyzer as FAR away as possible and if the spurs are gone, forget
it and delete the rest of this.

The radio synthesizer SHOULD produce such signals. There are reference
frequency spurs. It is rare that you won't see this - however, I realize
that your antenna vs. no antenna result is odd and I have no idea what the
reference frequency is or frequencies are.
Signal level into the analyzer.
Is the analyzer working properly.
Can you duplicate it?
Can you make any other changes which produces an expected result and get
what is expected or does something strange happen. Such as signal level
into the analyzer or power out of the radio.
SWR could be an issue as you speculate.
Without being there and trying other "crazy" things I can't speculate
further...
--
Steve N, K,9;d, c. i My email has no u's.