Re: [amsat-bb] SSB Electronics Preamps

["Simon Brown \(HB9DRV\)" <simon@xxxxxxxxx>]

I guess everyone on the list has seen the news from Yaesu that the FT-847 
has been discontinued because they can't get the parts.

I am not planning to use digital modes, but a year ago I was not planning to 
use satellites :-)

I guess I am awaiting P3E and in the meantime pounding the keyboard.

Simon Brown
---
www.hb9drv.ch www.laax.ch

RSGB HF Convention: Friday 7th - Sunday 9th October 2005
Holidays: Monday 10th - Thursday 20th October 2005

----- Original Message ----- 
From: "Howard Long" <howard@howardlong.com>
>
> 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!)
----
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