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Re: Icom 820H/ UT-50/AG25+35



Hi Stan,

At 07:33 PM 4/20/2004 +0000, Stan wrote:
>Try adding a good band pass filter between the transceiver and the antenna 
>feed line,
>is there an improvement in hearing a distant station ?    If there is 
>improvement,
>add the good band pass filter between the antenna and the mast mounted 
>preamplifier and check again.
>If preamplifier performance is better with the band pass filter, weather 
>proof it and leave in line.

Since the AG-25/35 are fed through the coax, it's probably best to mount 
the band pass filter only between the preamp and receive antenna, otherwise 
nasty things can happen.  I don't know for certain, but I have heard that 
you can blow out the preamp power supply (in the rig).  That doesn't seem 
to happen on the 910H as it detects this and turns the power supply off, 
but I don't know about the 820H.

I used a Diamond MX-72N duplexer as a Mode J filter, and it worked just 
fine. I connected the input of the 72N to the antenna and 70cm output side 
to the preamp.  I then fed the 2m side into a 50 ohm load  (You can find 
some diagrams on the back of the 72N package.)

73,

Emily



---------------------------------
W0EEC - CM87tm
AMSAT Area Coordinator - San Francisco Bay Area
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