[WriteLog] SO2V on RTTY - progress so far

Ian White, G3SEK G3SEK at ifwtech.co.uk
Sun May 9 17:32:24 EDT 2004

On Saturday I threatened to report back on the SO2V trial, so here it 
is... (it's quite long, so if this isn't your thing, you'd better stop 
reading now).

The everyday RTTY setup here is a 1000MP Mk1 with a HB control/audio 
interface, and a PC running WL and MMTTY under Win98SE. PTT is on the 
rig control port RTS, and keying is FSK through a second serial port, 
using the opto interface described in the WL Help pages.

The aims were:

* To get the sub-rx working as an effective second transceiver

* To have dual receive capabilities, either in-band split or dual 
diversity on the same frequency.

So here goes...

Using the very helpful information from the web pages of W9ALS and 
AA5AU, I added a second sound card which was fed from the sub-receiver 
line-level audio output through the usual isolating transformer. This 
operated with a second RTTYrite/MMTTY combination,

It's the same setup as you would use for SO2R, but both radios are 
inside the MP. The web pages explain how to start the RTTYrite/MMTTY 
software two times over, and get each one pointing to the correct sound 
card and radio.  When it's all done, you have:

* Radio L = Radio 1 = VFO A (main rx) in the MP
* Radio R = Radio 2 = VFO B (sub-rx).

It's tricky to start this setup, because the two instances of MMTTY 
always start with both configurations the same - including both windows 
in exactly the same place - so one of them always has to be reconfigured 
every time you re-start. Also it's different each time you re-start, so 
there are several combinations to learn. It's not difficult, but 
definitely not something to learn about during the contest!

WL, RTTYrite, MMTTY and the sound cards are all configured as if they 
were going to be hooked up to two totally separate radios. To make it 
work with the single MP, Radio R (sub-rx on VFO B) has to be told to get 
its frequency information from the "rig connected to COM1" - you can't 
get the actual frequency information from VFO B.

The second FSK output from the second RRTYrite has to go through its own 
separate COM port and opto interface, so you'll definitely need an extra 
serial card. The output of the second interface is simply connected in 
parallel with the first, so either one can key the radio.

So how did it play in the Volta?

Receiving through the two sound cards is excellent. With DUAL selected 
on the MP, you can tune the band with both VFOs at the same time, and 
watch two totally separate RTTY outputs. With DUAL off, you can have 
diversity decoding of the main rx audio - the sub-rx is muted, and 
doesn't have be tuned to the same frequency as the main rx.

The problem is that in order to keep a single coherent bandmap (we're 
talking single-band split, remember) you *must* tune the band and enter 
the station frequencies from the main VFO A. That is the only VFO for 
which WL knows the true frequency. If you enter stations from the VFO B 
window, they all appear on the VFO A frequency... which is probably your 
run frequency!

Transmitting  works fine. WL sends the messages to the correct callsign 
on the highlighted entry line - but *you* have to make sure it's going 
out on the correct frequency. When you swap log entry lines, you *must* 
remember to press the correct red TX button on the MP as well - WL will 
not do this for you. And if you forget... well, you know what happens!

That's how learned to keep the TX on VFO A, almost all the time. When 
running, I ran on VFO A and tuned the rest of the band between-times on 
VFO B. When S&Ping, I swapped the two VFOs and used the sub-rx to keep 
an ear on the run frequency.

Was it worth the effort? Yes, I think so. It's not for everyone, but it 
certainly increases the potential of a 
single-rig-single-band-single-antenna setup.

The main issues now, I think, are about better support in WL for SO2V: 
making the TX frequency follow the entry window when it swaps, and 
getting the actual frequency of the second VFO.

73 from Ian G3SEK

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