Thanks Jason
Pete
>> Not much chance of getting a spec-analyser, but curious what you mean by
>> unwanted mixing.
>>
>> TIA
>> Pete
>
> The analyser will give you a picture of what signals are present in and on
> either side of your link Rx's bandpass. I used to do RFI work at a busy
> mountain top broadcast and comms site and as the field of RFI is not very
> well documented, I had to learn most about it my self as I went along.
>
> If you can place your SA in place of your Rx, any direct fundamental
> interfering carriers can be checked against allocation records (supplied
> by
> DOC and some private publications) for correct freq and in some cases if
> relevant, mod type and index: eg 2 FM carriers adding will produce an
> intermod which has combined mod twice the peak deviation. This wide
> spectral
> occupancy can 'splash' into the bandpass of an adjacent Rx (freq-wise)
>
>
> Mixing of 2 or more carriers can occur in the power-amp of a one or more
> of
> the participating transmitters depending on how good their output
> filtering
> is. At the site I used to work at, a rule was promulgated that all Txs had
> to have at least one hi-Q resonator on their outputs.
> The same thing can occur in a receiver if the carriers are high enough in
> amplitude to get past the Rx's input filters and into the Rx's mixer at
> sufficient level. Mixing can also occur in metal joints which are
> corroded,..anything which presents as non-linear.
>
> I haven't had experience with uW ovens and their role in producing RFI,..
> and my work was in the VHF-UHF area.
>
> If you think your link Rx is too wide and is not providing enough
> rejection
> to adjacent carriers, you could try re-orientating the Tx and Rx so their
> aerials are operating on a different axis,..though they are probably a
> fairly wide beam.
>
> Jason
>
>