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Re: Help with 9.6Kbps with TS-2000 and DSP-2232



Freeman

"Freeman P. Pascal IV" writes:
> I'm stumped.

I put together some notes (long ago), maybe some of these may be of use:

Transmit side could be several things, deviation is certainly something to
look at. If you have a means of setting it then go for 3KHz or maybe a bit
less, otherwise theres some tricks to try.

1. Since repeaters are usually set up properly, use an HT to listen to your 
local 2m repeater, put an oscilloscope on the discriminator output and measure
the voltage when someone's talking, QSY the HT to the frequency of your 9600
tx, measure again, adjust deviation control in modem to give the same level;
thats a pretty good ballpark to be in and may be all thats needed.

2. Using your terrestrial packet software set tnc to FULLDUP ON, transmit 9600
on 2m, tune 70cm rx to third harmonic of 2m transmission, CONNECT (yourcall), 
send yourself long lines of data and observe reliability, reduce transmit data
voltage out of modem until reliability drops, note voltage, adjust voltage to
be three times the voltage noted (3rd harmonic also means 3x deviation on
70cm); you're in the ballpark again.

3. Using your terrestrial packet software put FULLDUP ON and CONNECT (satcall),
see if you get a connect; you won't be able to do anything when connected
except disconnect but it'll prove the radio side works. Play with modem o/p
voltage till you find the range that works, then set to mid-range. Or, if your
uplink works marginally, make up a LONG file to upload, say 25 K or so; 
entitle it TEST UPLOAD so folks won't bother to download it. Connect and 
upload. While its flowing (or more likely dribbling) play with the deviation 
level (the tx data voltage applied to the rig); you should find a narrow band 
where the data positively POURS upwards then leave it in the middle of that 
band.

I trust you've got the transmit data connected direct to the tx varactor diode
(maybe via 10K), because it WON'T work via the mic socket.

73
Richard W L Limebear G3RWL
g3rwl@amsat.org
FOC # 1188

          So many beautiful girls ..... (sob) so little time
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