[amsat-bb] Re: Eliminating Desensing

Jim Wright wrightjrjr at verizon.net
Mon Jun 30 11:02:02 PDT 2008

  A good start might be a "diplexer" at the antenna to terminate the 
energy you do not want presented at the receiver.  Put a termination on 
the uhf port and stick it in the vhf side of the feedline, assuming you 
are running two coax cables down to the shack.  If the VHF is desensing 
the UHF, do the same thing in the UHF feedline with a termination in the 
VHF port.  You don't say how much power you were running, but there 
comes a time when too much is too much.

Using two runs of 100 feet of 9913 on my TS2000, I only need the 
diplexer on the UHF coax.  Funny how the third harmonic on VHF gets to 
be awfully close to the UHF frequency of interest.
My watt meter can't tell the difference in UHF or 3 times VHF when I try 
to read the power.  HI.


On Mon, Jun 30, 2008 at  1:18 PM, Simon Brown (HB9DRV) wrote:

> Same here with TS-2000, 6ft *aluminium* boom and SSB Electronics 
> masthead

I'm thinking about a 6ft to 9ft fibreglass boom anyway, I would be
interested also in user comments.

Simon Brown, HB9DRV

 From: "Reicher, James" <JReicher at hrblock.com 
<mailto:JReicher at hrblock.com>   <mailto:JReicher at hrblock.com> >

> 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.

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