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Re: 2 meter uplink interference on 70 cm downlink




Hello Erik.

05 Aug 00 14:48, you wrote to Tony Langdon:

 ES> The interference occures only whil I am transmitting.
 ES>
 >>
 >> How well can you hear other stations on the bird?
 >>
 ES>
 ES> I can hear other stations quite good. When I am transmitting it is a
 ES> lot worser.
 ES>
 >> What does the interference sound like?
 >>
 ES>
 ES>
 ES> Difficult to describe, since I have also LF detection of my SSB signal
 ES> in my headphone (the Donald Duck voice). At the other hand I see the
 ES> S-meter of the 70cm set moving to S4 (the downlink signla is only S2)
 ES> when I am transmitting.

Sounds like your uplink is getting into the downlink.  The filtering
suggestions offered by others are likely to help, guiven that you're using
separate transceivers.

 ES> By the way I am using:
 ES>
 ES> FT 290 R, 2 meter all mode with amplifier (25Watt) , into a J - pole
 ES> antenna
 ES>
 ES> FT 780 R  with a 10 loop helix antenna and a SSB Maxi amp
 ES> pre-amplifier at the antenna.
 ES>
 ES> When I am using mode A on RS12/13 I don't have any problems (except
 ES> somtimes LF detection on my headphone).

Would seem you're getting harmonic interaction between the 2m uplink and the
70cm downlink, as others have suspected.  Needed to ask those questions to rule
out possible downlink problems.

Tony

.. Earth: A solid substance, much desired by the seasick.
--
|Fidonet:  Tony Langdon 3:633/284.18
|Internet: tlang@freeway.apana.org.au
|
| Standard disclaimer: The views of this user are strictly his own.


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