[amsat-bb] Duplexer to Dual-Band Vertical

[Hasan al-Basri]

Using duplexers like this works very well, if they are good duplexers, like
the Comet. I use them all over the place as filters.

I have tested them at 80w output on 70cm with a 2m ARR Gasfet preamp ahead
of a FunCube Pro + Dongle. Works perfectly and NO intermod, NO desense.

They are an ideal solution to full duplex operations at a very reasonable
cost.

I have tested them on an interlaced yagi (with single feedpoint at the
yagi) 5 EL on 2m, 8 EL on 70cm, fed with 65' of 1/2" hardline (duplexer in
shack), as well as a pair of M2 EggBeaters 7' off the ground fed with 80'
of LMR-400. Duplexers at each end.

Performance:

Usable satellite signals at -0.5 deg EL on the tower antenna. No desense,
no intermod. SNR 10 dB, Q5 SSB copy both ways. Repeatable.

If that isn't ideal, I have no idea what is.
73, N0AN
Hasan


On Tue, Feb 11, 2020 at 7:09 AM VA3ASE via AMSAT-BB <amsat-bb at amsat.org>
wrote:

> Good morning,
>
> I was chatting with a friend about his experimentation with amateur
> satellites and have been pondering if his setup is "safe" for his radio. He
> is running an FT-847 through a duplexer (diplexer if you want to be
> pedantic) and into a dual-band vertical base antenna on his roof.
> Definitely not an ideal setup, but meant to be temporary until time and
> better weather allow. He has managed to make some FM contacts on AO-92 with
> it.
>
> My concern is him using a duplexer in this manner while running full
> duplex. I suppose this is similar to what people must do if using an Elk
> antenna. I just worry about there being enough isolation between the ports
> and damaging his transceiver. Are there others using similar setups or is
> this something to avoid?
>
> 73,
> Alex VA3ASE
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