At 8/2/2004 02:45 PM, you wrote:
>Hi all,
>
>I'm looking for a VHF duplexer for a portable repeater.
>
>I see some "mobile" duplexers on ebay. I assume they're notch only.
>
>How well would these work on 2M at a 600Khz split?
They won't. However, if they have 6 sections (6 adjustment screws), they
probably can be tuned for a 2.5 MHz split. I have a couple that yield just
under 70 dB of isolation at this spacing. When used with a good quality
G.E. or Motorola radio, they do provide sufficient isolation. Some mobile
duplexers just do make the 2.5 MHz split, & as a result the loss on those
is a bit higher. One of mine is 2.1 dB loss on both ports, the other 1.8 &
1.0 dB.
I'm currently using one with a G.E. MVP radio to make a very small,
completely self-contained portapeater (just add 12 V & antenna). It
operates on 147.585 in, 144.93 out. 20 watts out, 0.40 �V for 12 dB SINAD
(at duplexer antenna port) & no desense.
Bob NO6B
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