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[TowerTalk] Filters for VHF/UHF

To: <towertalk@contesting.com>
Subject: [TowerTalk] Filters for VHF/UHF
From: km1h@juno.com (km1h@juno.com)
Date: Thu, 1 Apr 1999 11:00:02 -0500


On Wed, 31 Mar 1999 09:14:52 -0800 "Mason, Ken R" <ken.r.mason@intel.com>
writes:
>Hello Carl,
>
>What about using those cheap 144/440 MHz Duplexers? Will they filter
>adequately compared to those $90 intermod filters? 

I changed the Subject line.

Good question Ken, I do not have the answer but will borrow one and plot
on the network analyzer.  I do own Diamond triplexer that I use on a
TM-941A 144/440/1290 tribander and will plot that also. I would think
that they have >25 dB band to band isolation but thats a real off the
wall guess.


I think cavity 
>filters
>are too complicated and narrow to work for my application. 

I was not talking about cavities in the shack. Instead go to www.dci.com
and check out their ham bandbass filters. Impressive and quite
inexpensive. I will be adding a new pager to my commercial tower and the
company is providing me with DCI 222 and 432 MHz filters.


My station 
>setup
>is a IC-706 for 6M, IC-275H for 2M, and IC-475H for 70 cm. I will be 
>adding
>PBT filtering soon to the IC-*75H radios. Any additional filtering is
>welcome.

One problem with those radios is broadband TX noise, filters may help but
not if the noise is actually being transmitted on the other band.
Are you sure another tower is out of the question !?!

73  Carl  KM1H



>
>73,
>Ken
>KC6TEU

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