[amsat-bb] Does one 847 equal two 817's?

Paul Stoetzer n8hm at arrl.net
Thu Nov 20 22:59:10 UTC 2014

I can't answer questions about how the 847 works as I've never used
one, but I'd think you'd want to use the VFO tracking and inverting
capabilities to navigate the passband.

Using two 817s together on the linear transponders does take a bit of
practice. It's relatively easy to find a clear space, find your
signal, and call CQ. It's a bit more complicated to navigate the
passband since the two 817s aren't tracking each other and it takes a
bit of mental arithmetic to get on frequency once you change your
receive frequency. This is where the VFO tracking capabilities of a
satellite radio come in handy and I've thought about designing an
Arduino interface that links 2 817s (or 857/897 - same CAT protocol)
together via their CAT ports (when you tune one, the other tracks).
Incidentally, Icom used to make a device to do just this with two Icom
radios (the CT-16 Satellite Interface Unit).

Of course this is how it was done by everyone back in the 1970s and
early 1980s. Before satellite transceivers came on to the market,
everyone was using two separate radios!

I'd make a video, but I'm a bit short of hands when operating the two
817s (maybe I should get a GoPro)! I could do a video simulating a
pass and showing you how I tune around. I might do that tonight and
I'll post the link if I do.


Paul, N8HM

On Thu, Nov 20, 2014 at 3:56 PM, Bill ACITO, W1PA <w1pa at hotmail.com> wrote:
> I see a lot of current portable transponder ops running two rigs (most
> likely 817's).  Folks seem to be unencumbered by the lack of tracking and
> Doppler coordination between the two radios. Dare I say it --  old school?
> Despite the tracking and inverting capabilities, is there any reason I
> couldn't run my 847 in the same "mode", using the two separate VFO dials
> like two 817's and nothing else? Am I missing something?
> Any one, from the various AMSAT portable ops, have a YouTube video showing
> _in detail_ how you are running two 817's?
> Anyone else run your 847 this way?
> Bill
> W1PA
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