[amsat-bb] Re: Eliminating Desensing

[John W Lee]

Something else to try, 
hook up the transmit side of the rig to a dummy load  
and see how your receive is.  It may be  something in the 
rig causing it, not the proximity of the antennas. 

I get this problem sometimes and have other vhf/UHF antennas
that are maybe 50 feet away from the satellite antennas.  I can transmit
on an antenna 50 feet away and pointed away from the receive antenna
and still get it sometimes. 

73,
John K6YK


On Mon, 30 Jun 2008 13:22:09 -0400 (GMT-04:00) Andrew Glasbrenner
<glasbrenner at mindspring.com> writes:
> It's unusual to see desense on 2m receive from a 70cm uplink, but I 
> think the same solution can be applied. Many use a common 2m/70cm 
> diplexer as a high pass/low pass filter. In this case you would want 
> to feed the 2m antenna to the common port of the diplexer, and the 
> 2m port of the diplexer to the input of either your preamp or rig if 
> you do not have a preamp. This blocks your transmitted signal from 
> the receiver/preamp input very effectively. 
> http://www.amsat.org/amsat-new/articles/Mode-J/ describes this for 
> 70cm desense issues.
> 
> Another option is to use a preamp with good filtering on the input. 
> I had issues with Mode J desense with my Icom AG-35 preamp, but have 
> none now that I have switched to SSB Electronics preamps.
> 
> As always, Your Mileage May Vary (YMMV).
> 
> 73, Drew KO4MA
> 
> -----Original Message-----
> >From: "Reicher, James" <JReicher at hrblock.com>
> >Sent: Jun 30, 2008 12:50 PM
> >To: amsat-bb at amsat.org
> >Subject: [amsat-bb]  Eliminating Desensing
> >
> >I got significant de-sensing of my 2 meter downlink from my 70cm 
> uplink at Field Day.  I know a good part of it was due to the short 
> cross-boom (about 4 feet) I was using.  I would like to decrease the 
> de-sense on this set-up before I permanently install it at my home 
> station.  Any and all suggestions are welcome.
> >
> >73 de W0HV, Jim in Raymore, MO 
> >Light travels faster than sound...  This is why some people appear 
> bright until you hear them speak.
> >
> >_______________________________________________
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> 
> 
> 
> _______________________________________________
> Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the 
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