[TowerTalk] Coaxial stub filters

[Michael Baker]

Hello Dennis,

	Try looking up K1TTT and look under his technical info page on stub
filters.  He has a lot of good info and links to sources.

	I put together a single filter in a can with a switch that changes
bands and it works pretty well.  Gives about 18 DB of notch.  The better the
cable the better the notch.  LMR400 will give a notch on an analyzer of
almost 30Db on 2 meters but I don't know what it will do on the HF bands.

Michael Baker  K7DD
k7ddmjb at qwest.net

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Dennis W0JX
Sent: Wednesday, June 25, 2008 5:50 PM
To: towertalk at contesting.com
Subject: [TowerTalk] Coaxial stub filters

List members:
I am trying to make reduce interstation interference for our Field Day
operation by utilizing quarter-wave coaxial stubs. I made a 40 meter stub
and put it at the output of a TS-850 which was feeding a 20 meter ground
plane. The stub reduced 40 meter signal response considerably and had no
effect on the rig's SWR indicator or the antenna match.
 
The 40 meter stub reduced the interference caused by the 40 meter
transmitter but not significantly. So I put a 20 meter quarter-wave stub on
the back of my 1000MP. That did seem to cut down on the 20 meter transmitter
noise but the SWR at the output of the MP jumped dramatically. Is this
normal? Obviously the 20 meter stub must be putting a considerable loading
or reactance on the output of the rig.
Any ideas would be appreciated.
 
73, Dennis W0JX/8


      
_______________________________________________



_______________________________________________
TowerTalk mailing list
TowerTalk at contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk