Interesting question. All radios put out spurs,harmonics, splatter
etc. It is a matter of level. An example; years ago I heard a lower
sideband signal on the upper part of 10 meters and waited for an ID. It
was a local ham. I did a comparison of his real signal (on 10 meters but in
the more used area) and the other one I was receiving. The spur was very
low in level compared to his real signal ( more than 60 db down).
My next question was," is this signal an image or something from my
receiver or was it his transmitter?"
I changed receivers, he was rag chewing for some time, ( a boatanchor with
a completely different conversion scheme) and the signal was still there.
Yes, it was a spur but it was not one beyond the specs for that particular
transceiver (TS520).
So the real question is what is the level of the spur in absolute
terms (dbm) and in relative terms when compared to the real signal
(db). This can only be done by measuring the signal levels at the antenna
connector into the constant impedance of a dummy load.
A calibrated coupler with lots of attenuation and a general coverage
receiver would be a start. Just a simple capacitive coaxial coupler
calibrated at the various frequencies ( it would be frequency dependant)
would be a start. You don't have to have elaborate spectrum analyzers or
megabucks of test equipment to make fairly good measurements as long as you
have a calibrated signal generator such as an URM 25 or TS497 or HP606 or
anything similar that you can get at hamfest relatively cheap. Just don't
blow out your test receiver.
73
Bill wa4lav
At 11:36 AM 8/19/2003 -0500, you wrote:
>To further stir the pot about the Omni C on 17m, I have received several
>emails from people using them on 17m saying that they were told that they
>were putting out spurs.
>T Ts standing is that they are ok on 17m. Does that mean that they are clean
>or just that they will tx and rcv on 17m? BIG difference
>What my real question is, has anybody tried a spectrum analizer on one and
>found where the spurs are? I have had enough response to my original
>question about them on 17m that I have no doubt that they are putting out
>spurs somewhere and because of the IF being what it is probably no chance of
>cleaning it up.
>
>73 & Thanks Paul K9OT
>
>
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