[600MRG] CMSK Initial Test Results

[Neil Klagge]

John (xka)
No trace of you on my CMSK screen last night.

I am looking forward to trying that mode as I think it will be a good
alternative to PSK on 630m, especially since it does not require a linear
PA. It seems like a natural.

Neil, XSV


On Sat, Feb 8, 2014 at 9:24 PM, John Molnar <wa3etd at gmail.com> wrote:

> TTnx to those reporting!  So far:
>
> Ken XXM had perfect copy in CMSK63.
> John XIQ had essentially perfect copy once getting tuned.
>
> The first half hour ran well.
>
> However, after restarting in CMSK31 for the second half hour run my PA
> tripped off due to SWR.  I switched into dummy load, and PA and outboard
> LPF were fine.  An analyzer check of the antenna was not pretty.  I checked
> the tuning box outside and nothing immediate jumped out, so we'll deal with
> that tomorrow.
>
> The SWR protection scheme here is simple.  Reverse voltage is sampled
> with an op amp that drives the a/d converter of a PIC processor, which also
> watches PA current and voltage.  If preset parameters are exceeded, a relay
> is activated that opens the drain supply.  This is a work in progress and
> was a clip lead special tonight as the test was a long key down session for
> sure.
>
> Again, thanks to the reporters.  No conclusions at this time yet but
> obviously CMSK63 works as a possible keyboard QSO mode.
>
> John XKA
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