[MRCG] band conditions Saturday night

[epvgk at limpoc.com]

On Sun, Nov 29, 2015 at 05:58:06PM -0800, Mark J. Blair wrote:
> 
> > On Nov 29, 2015, at 17:07, epvgk at limpoc.com wrote:
> > I'm copying your opening message more or less with ST-6. 
> > Transmitting is problematic as the high tone is outside the
> > transmit bandwidth of my ic7000, so I need to figure out 
> > some clever split setup to keep feeding the ST-6 high audio
> > tones while letting the radio transmit/receive 1000 hz lower.
> > Anyway I have no idea if I'll hear anyone else but I'll
> > leave the machine on and printing anyway. 
> 
> I cheat by setting my modern rig 500 Hz higher to center the tones in its passband. We picked the tones for compatibility with the PRC-47 and its matched FSK modem, since it's the least frequency agile rig we expected to be used on the Clatternet.
> 
> For a numerical example, I presently have the radio set at 3587.5 KHz, and my center freq. at 1500 Hz in fldigi. A PRC-47 would be set to 3587.0, but it's modem's center frequency is at 2000 Hz so the actual mark and space frequencies come out in the same places on the air. We call the channel "3587" as that is the tuned frequency on a PRC-47 (maybe on a GRC-122/142 also?), but actual mark and space tones are higher due to the AFSK modems. Things get most difficult for true FSK rigs like the GRC-46, since they need to set transmitter carrier frequency right on one of the tones, but they also tend to have touchy tuning. It's all a compromise to maximize the number of different green rigs that can play.
> 
> Anyway, I had pretty good comms with AG6EB from San Fransisco here in Riverside, and noisy comms with K6NE from Ventura.
> 
> Heard a weak station a couple of minutes ago, but zero copy.
> 

This is more or less what I was doing too. I set up two frequencies in the IC7000: 
one that puts the audio output tones where the ST-6 wants them, and one that puts
the generated tone in the middle of the IC7000's transmit passband. When I want 
to transmit, I just shift to the higher dial frequency and transmit, then switch
back to the lower one to let the ST-6 demodulate. Only downside is I can't easily
copy with both fldigi and the ST-6 at once until I figure out how to make fldigi's 
concept of "split" sync with the radio's. But anyway, this worked ok. 

Here's a scan of the print from tonight - not great, but there was a lot of local
noise. This is probably still better than 40M since it was pretty on and off, 
instead of just shutting down entirely like on 40M last time. 

http://wtrc.net/clatternet.pdf (Sorry about the crappy scan.)

The web project I mentioned is a combo hardware/software setup to present a web
page with a text terminal which relays character by character to a TTY loop
instead of line by line, so for instance I can have a realtime keystroke by 
keystroke conversation between a local teletype machine and an internet 
visitor on the web page. 


eric