[GreenKeys] HoffNet on half-kHz frequencies annd a Suggested Final Choiice

Fri, 7 May 2004 11:05:23 -0500

Hi Eric,

That is a very helpful analysis.  I continue to monitor in the 10.127 -
10.127300 region and I am hearing quite a lot of Pactor calling and an
occasional link up.  It appears this is some sort of net frequency as
well or something similar.  I don't have pactor capability presently set
up so I cannot tell who it is but it has been pretty regular.

Our earlier frequency of 10.1375 and vicinity has remained remarkably
clear except for a potential conflict with the Clatter Net on Saturday
mornings which is on 10.1370 Mhz

I suggest we go ahead and use 10.137300 to 
1)  avoid the significant pactor activity around 10.127, 10.133
2)  Allow operators of Military radios to tune the Mark frequency
accurately
3)  Avoid commercial station on or about 10.130 and 10.140 

I think everyone will respect the Clatter Net's use of the frequency on
Saturday mornings when all of us can stand down for a few hours or join
in with them using their frequency of 10.137000 and 850 shift.

Trying to accommodate everyones' wishes and select a clear channel that
is not occupied by a Commercial Broadcast station, existing net,
automated Pactor frequency, etc. has been a problem.  I guess there is
no way that we can please everyone and a choice has to be made.  I am
going to select 10.137300 as the mark frequency and use 170 shift since
there has not been any support for the suggestion of using wider shifts.

So there it is gang:  10.137300 mark.  I will begin transmitting on that
frequency later this afternoon.  Please listen in and give me signal
reports either via RTTY or on GreenKeys.  We need to survey propagation
conditions and see if this frequency will give us adequate coverage.

Best regards -- Roy Norris, K4EEG now stuck on 10.137300 Mhz

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Eric Scace K3NA
Sent: Friday, May 07, 2004 7:13 AM
To: Roy Norris; [email protected]
Subject: RE: [GreenKeys] HoffNet on half-kHz frequencies

Hi --

   I am still the custodian of a AN/GRC-106A (with a dead oscillator,
but that's another story), which has seen many years of
service on autostart frequencies in the Navy MARS program.  So I have a
little experience with this generation of military radios.
And, as a result, I'm puzzled about the concern over older radios with
step tuning that only handles exact 1 kHz steps.

   The GRC-106A has a vernier tuning control to allow the transceiver to
operate between kHz steps.  The original version did not.
This radio is USB and CW only -- no FSK nor LSB.

   So let's assume we wish to accommodate transceivers like this:
-- exact kHz step tuning
-- no vernier controls
-- no FSK mode
-- USB only for sideband modes.
-- TU such as an ST-6 accepts standard tones of 2125 and 2295 Hz, but
can be reversed so that 2295 is interpreted as mark.  The
reversed tones compensate for the use of USB.

   In this case, the proposal to use 10127.0 as the mark frequency
instead of 10127.5 doesn't help at all.  There will be no way to
tune such a transceiver to place a mark signal on 2295 Hz.

   Therefore, we have two choices:
   a) place the mark frequency on x + 2.295 kHz, where 'x' is an exact
kHz.  But many modern ham rigs with true FSK transmit ability
do not synthesize down to the 1 Hz level.
   b) place the mark frequency on x + 2.300 kHz.  That means a radio
with 1 kHz step tuning will be 5 Hz off, which is within the
error tolerance of the filters in most TUs.
   b) forget about supporting radios with 1 kHz step tuning.

   Taking into account other monitoring results and comments, we could
choose a mark frequency of 10127.300 kHz (and space frequency
of 10127.130 kHz).  That seems relatively clear, according to past
reports.  And it seems to allow folks to choose a wide range of
radios to play with.

   And I apologize for muddying the waters further on this project!

-- Eric K3NA

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