[GreenKeys] HoffNet on half-kHz frequencies annd a Suggested Final
Choiice
Bob Camp
[email protected]
Fri, 07 May 2004 19:44:02 -0400
Hi
Ok, 10.137300 MHz +/- 0.00001 Hz mark frequency it is.
I think we have probably analyzed this about as far as we are going to.
I suspect that if we watch *any* frequency long enough we will find
organized traffic on under some conditions. It sounds like this is a
reasonably clear frequency and that we are not going to be stepping on
any big toes by firing up on it.
So to repeat the process for this channel:
Mark is 10.137300 MHz
Space is 10.137130 MHz
Center tuning radios set to 10.137215 MHz
USB radio with a 2125 / 2295 TU tunes to 10.135005 MHz (reverse)
LSB radio with a 2125 / 2295 TU tunes to 10.139425 MHz (normal)
USB radio with a 1275 / 1445 TU tunes to 10.135855 MHz (reverse)
LSB radio with a 1275 / 1445 TU tunes to 10.138575 MHz (normal)
Assuming I got all those right that should be enough to get a few of us
on the right frequency.
Take Care!
Bob Camp
KB8TQ
On May 7, 2004, at 12:05 PM, Roy Norris wrote:
> 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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