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RE: SSB Electronics Preamps



Hi Simon

> While still getting my station sorted out I am using a FT-817 for
satellites.
> I just bought and installed the SSB Electronics 70cms masthead preamp.
Makes
> an enormous difference - I have 8m of Aircell 7 between radio and antenna.
> (The FT-817 is very badly misaligned.)
>
> If there is anyone who hasn't tried a preamp like this and who thinks
their
> radio may be a bit deaf then all I can say is 'give it a go'. It's driven
by
> VOX, even a clown like myself can set it up :-)
>
> Now all I need to do is wire up the 2m preamp, problem is I have run out
of
> N-type connectors and they cost a fortune in Switzerland :-(

If you have a fairly permanent installation you may want to consider some
kind of sequencing, hard switching the unit. The VOX is good on these units,
and I have no direct experience of it failing, although I am never sure how
much to trust it!

The FT-847 is great in this respect as it can be configured to provide DC
right up the coax on receive.

As well as hard switching, I have modified these units in the past to reduce
the VOX TX-RX switching. This is important when operating in-band digital
modes with short TX Delays. Admittedly there aren't any satellites operating
in-band on 70cm at the moment, but terrestrially of course there are lots of
in-band half duplex nodes. The ISS operates in-band digital modes on 2m.

For commanding SSETI Express we will be using an in-band 70cm half duplex
mode, necessitating reduced TX-RX switching time. FWIW the docs for the hard
switching mechanism for the TS-2000 and reducing the VOX TX-RX switching
time are at http://www.g6lvb.com/sp7000ts2000.doc (379KB). The TS-2000 also
allows a delay of up to 25ms to be configured between switching from receive
to transmit after signalling the change to the sequencer.

(Note: If you're operating SSB without hard switching, it is inadvisable to
reduce the VOX TX-RX switching time!)

73, Howard G6LVB
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