The deadlines for e-mail logs are now past. Those that have been mailed
must be postmarked by March 31, 1999 and reach me by May 1, 1999. The
claimed scores must be to CQ for publication in the August issue and the
final results should be complete September 15 for the December issue.
The claimed scores will be posted to the CQ magazine web page about
September 1st. As always the final results will only appear in the
December CQ and the French version of CQ. Revisions to 1998 results and the
contest rules will finally appear on the CQ Magazine web page.
Dave K4JRB
CQ 160 Contests Director
--
CQ-Contest on WWW: http://www.contesting.com/_cq-contest/
Administrative requests: cq-contest-REQUEST@contesting.com
>From Dick Green" <dick.green@valley.net Sat Apr 10 05:09:38 1999
From: Dick Green" <dick.green@valley.net (Dick Green)
Subject: [CQ-Contest] MFJ Voice Keyer
Message-ID: <001401be8308$20c040c0$0ba473c6@tpk.net>
Dave,
I had problems with hum, too, using a TS950SDX. I found that removing the
jumper between pins 33 and 34 on header HD1 solved the problem. This
disconnects PTT from MIC GND. PTT still works when grounded to the MFJ
circuit ground, probably because all the chassis grounds in my station are
bonded together. Still, the MFJ design is puzzling in this regard.
My big problem was insufficient mic gain when recording with a Heil 4 or 5.
The internal mic was fine, but sounded too different from my Heil. I ended
up recording from the mic monitor in the transceiver (i.e., I connected the
transceiver's speaker output to the MFJ's audio input jack on the back and
switched on the transceiver's mic monitor.) This works very well and
provides a variable mic input using the transceiver's monitor volume pot. Of
course, the transceiver's mic processor should be switched off when
recording.
Below is a character diagram of the message abort modification. View this
message with a fixed spaced font like Courier and set the right margin as
wide as you can to see it properly:
to R10/U1 pin 24
|
|
_
1N4148 diode ^ 1N4148 diode
to J6 pin 7 ------>|------+----- to R6/D5 |
| |
|-----------------|(-----|
+ - |
.47uf # 100K ohm resistor
#
|
-_- GND
-
The connections to J6, R6 and R10 are tack soldered. The abort line from the
computer is connected to pin 7, J6. The pulse from this line is fed to the
PD input (pin 24) of U1, the ISD1020A voice recorder chip, aborting the
message output. The pulse is also fed to the input of the flip flop latch
formed from two of the gates of U2, resetting the latch and the output
relay. The RC circuit used to feed the pulse to the PD input shortens the
pulse duration so that the signal sent to the latch lasts longer,
effectively simulating an EOM (end of message) pulse to the latch. (Just
pulsing the PD input without the pulse duration modification and the second
signal to the latch causes the relay to go off and then back on again,
keeping PTT keyed after the abort.)
Use this circuit at your own risk. I'm not an electronics engineer -- I just
buzzed this circuit out by reading the ISD1020A chip specs (on the web at
ISD's site), the MFJ schematic and through trial and error. It does work for
me, however. The circuit requires building the transistor voice keyer
interface documented in the NA manual, which buffers the positive keying
pulses from the LPT port. I found that I had to put a diode in the SW RETURN
line of the circuit. Otherwise, my PLAY LED would glow faintly when the
computer booted up and the voice keyer was switched off. Turning the keyer
on and off extinguishes the LED. I'm powering the transistor interface from
the +5V line on pin 1 of J6, and I think a pulse from one of the pins
on the LED port puts a voltage on this line, which in turn charges a
capacitor somewhere (probably the 47uf cap on the 5V regulator.) Adding the
diode seems to have fixed that problem.
Hope this is of help.
73, Dick, WC1M
--
CQ-Contest on WWW: http://www.contesting.com/_cq-contest/
Administrative requests: cq-contest-REQUEST@contesting.com
|