I've been using the circuit shown on this page for over 20 years with success.
https://www.aa5au.com/rtty/fsk-interface/
Don AA5AU
-----Original Message-----
From: RTTY [mailto:rtty-bounces@contesting.com] On Behalf Of
groupsrichart@gmail.com
Sent: Friday, February 23, 2018 1:49 PM
To: KenwoodTS-590@yahoogroups.com; rtty@contesting.com; TS-590@groups.io;
TS-590S@yahoogroups.com
Subject: [RTTY] FSK Keying of TS-590SG
I would like to hear from anyone who is successfully keying the FSK and PTT
lines via the ACC2 connector on the rear panel of the TS-590SG. What serial
adapter and what hardware interface are you using to do so?
I have tried two different interfaces using optoisolators to attempt FSK and
PTT keying from a serial card to the rear panel ACC2 connector. Both attempts
have failed. I am using MMTTY software for keying and I do get the requisite
signal change on TXD pin 3 (FSK) and RTS pin 7 (PTT) lines. I have also
verified proper setup of the '590 by manually grounding the inputs PKS pin 9
(PTT) and RTTY pin 2 (FSK) on the ACC2 connector.
However, I *think* the problem lies with the serial card not providing enough
voltage/current for the optoisolators to completely turn on and provide a hard
ground to the ACC2 inputs. I have tried two different serial cards and one
swings from -4.9 to +5.0 VDC on the data lines and the other card swings from
-3.8 to +3.9 VDC. The cards I am using are a two port generic PCI Express
SI-PEX15037 and a four port Perle Fast 4 PCI card. Does anyone know of a serial
card that has a full -12 to +12 VDC swing?
One of the hardware interfaces has 4N25 optoisolators and the other uses
Fairchild FOD852 optoisolators. There are 1K series resistors in the input line
to the optoisolators and I have tried various values (100,
220 & 470Ω) with limited success but nothing consistent.
While my objective was to keep the rig isolated from the computer, I am
thinking about building an interface that uses NPN transistors for keying. Is
anyone using NPN transistors to key their '590? Are you tying the ground from
pin 5 of the RS-232 port to the pin 4, 8 or 12 ground of the ACC2?
Any input is appreciated...I have been off RTTY since purchasing this rig in
November and I want to get back on the bands.
Thanks,
Tim WS4V
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