[OZAPRS] Help with MJF-1270b and UI-View32
gordont63 at internode.on.net
Sun Dec 30 18:08:43 EST 2012
In the past I have had to calibrate these to get them working.
There is a procedure to do it and after that one of my non decoding 1270Bs
I have pasted it below here, not sure how it will turn out. Apart from that
make sure you are on the correct frequency. 145.175
Have you ever wondered to yourself whether or not the Packet TNC you are
using may or may not be generating correct mark and space tones in reference
to the proper frequency? As the owner of 5 MFJ 1270/1274 TNCs, the above
question came to mind. I am not equipped to make adjustments on these TNCs
with the use of various testing devices, and turned to the MFJ Owners Manual
for a possible remedy. They tell you in the Manual how to adjust the tones
if you desire HF operation (300 Bps) using their 1270B, or 1274 Model, but
when trying to find out how to check for proper calibration on the VHF/220
Mhz/UHF (1200 Baud) -- it's not there.
The TNC 2 has a couple of GREAT features built in to its software. CALSET
and CAL are in the list of Parms, but not explained in detail that would
enable the average packeteer to do his own calibration.
1. 1200 Hz. - MARK TONE (Low tone )
2. 2200 Hz. - SPACE TONE (High tone)
3. 1685 Hz. - CENTER TONE (Demodulator)
On the CENTER FREQUENCY tone, it states in the TNC 2 Manual that 1700 Hz is
ideal. Continued experimentation has shown that 1685 Hz is best. If you are
experiencing alot of retries, and having a difficult time with connects,
chances are that your TNC is not generating compatible Mark and Space tones.
To calibrate the 1200 Baud tones on your TNC 2 or Clone. Follow these
1. Remove the cover of your TNC. Make sure the HF/VHF button is in the "VHF"
2. Get a screw driver small enough to adjust the trim pots R-76 through R-79
located toward the rear center of the TNC circuit board.
3. Boot up your computer, and enter Command Mode (CMD:) on your TNC.
4. Try to listen on another Transceiver, possibly a Hand Held Radio or
monitor of some kind, and pick a clean freq. (simplex) with LOW pwr.
This is helpful, but not required.
5. Enter this command from command mode:
CALSET 438 or (n=525,000 / 1200 + 1) which in either case will equate to 438
or thereabouts. This is your MARK tone CALSET number or 1200 Hz tone.
6. Remove the jumper from JMP 8 and place on JMP 9 Pins 1 and 6. (If you are
facing your TNC pins 1 and 6 are on the far right).
7. Type CALIBRA or CAL. Hit the letter "K" and then the space key to get the
lower of the two tones.
you may want to remove the jumper from JMP 5 to use on JMP4 to override the
watchdog timer circuit.
8. Adjust R-78 until the you hear a change in pitch of the transmitted tone,
AND both the CON and STA led's light up and stay lit, or at least alternate
back and forth the same rate. Ideally, they should both stay lit
9. Hit the "K" again, and then "Q" (to quit calibration) and then go back to
10. Give the TNC the command:
CALSET 239 or (n= 525,000 / 2200 + 1) which equals a CALSET number of 239.
11. Repeat step 7. Repeat step 8, but adjust R-77. Repeat step 9.
12. NEXT - REMOVE the jumper from JMP 9 (Pins 1 and 6) and place the jumper
on Pins 2 and 5. - the center two pins of JMP9.
13. Go to CMD: mode and type this:
"CALSET 157" or (n= 262,500 / 1685 + 1) which would equate to a CALSET
number of 157. This is your Demodulator/or center freq of 1685 Hz.
14. Repeat step 7, this time adjusting R-79 for the best condition of the
CON and STA LEDs (both lit at same time).
15. Replace JMP 8 (from JMP9) and replace JMP 5 (from JMP4).
Once you have done all of the above, you have successfully calibrated the
TNC's tones. LAST BUT NOT LEAST...follow the MFJ or TNC 2 Manual on how to
properly set the deviation level adjustment (R-76) so that your transmitter
puts out in the neighbourhood of 2.8 to 3.0 kHz of deviation.
From: ozaprs-bounces at aprs.net.au [mailto:ozaprs-bounces at aprs.net.au] On
Behalf Of Phil Kern
Sent: Sunday, 30 December 2012 14:10
To: ozaprs at aprs.net.au
Subject: [OZAPRS] Help with MJF-1270b and UI-View32
Recently dusted off an old MJF-1270b which I used to use with packet many
Now trying to configure this with UI-View32. Im unsure about the config
within the Comms Setup Area.
It appears to be connected on the default setting. Just cant seem to
decode anything on the terminal screen.
Have followed the Config Guides on aprs.net.au APRS via Internet seems to
Any help or pointing me in the right direction, would be greatly
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