Well, tonight I tried Jim's suggestion of putting +12V directly on the
input to the optoisolator through a 1k current limiting resistor. I was
able to do this by unplugging the serial cable from my FSK interface and
injecting the voltage directly into the pins of the DB9 connector. When
I did this each output from the optoisolator was able to pull fully low
(less than 0.05V) and activate the RTTY and PTT inputs on the ACC2
connector.
So connecting +12V into pin 7 of the DB9 and ground to pin 5 turns on
the optoisolator and activates the PTT line. Checking the voltage from
pin 7 to 5 still shows 12V. Checking the output at the optoisolator
shows 0.05V.
Now, if I go back to the serial cable connected to my computer's serial
expansion card, I measure +11.5V from pin 7 to ground pin 5 when it is
not connected. When I connect the cable to the FSK interface card, the
voltage from pin 7 to 5 drops to 7V. The voltage at the output of the
optoisolator drops from 2.3V to 0.54V...not low enough to activate the
PTT line.
So, this is starting to look to me as if the serial adapter card is not
sourcing enough current to operate the optoisolators. Or the cable has a
high resistance connection somewhere...11.5V with no current draw but
drops to 7V with a load.
Hmmm, I will have to think about this one for a while. Time to get some
sleep! Any thoughts or suggestions appreciated.
73,
Tim WS4V
On 2/25/2018 11:54 PM, groupsrichart@gmail.com wrote:
Jim,
..Did you try shorting the lines directly to ground? YES
..Did the radio transmit? YES
..Did you manually key the radio with it's microphone and ground the
FSK line? YES
..Did it shift? YES
..Did you try putting +12 volts directly on the input to your opt
isolator with it hooked to the radio? NO...good idea...I will try it
tomorrow.
Thanks and 73,
Tim WS4V
On 2/25/2018 11:18 PM, Jim W7RY wrote:
Should be more than low enough.
Did you try shorting the lines directly to ground? Did the radio
transmit? Did you manually key the radio with it's microphone and
ground the FSK line? Did it shift?
Did you try putting +12 volts directly on the input to your opt
isolator with it hooked to the radio?
73
Jim W7RY
-----Original Message----- From: Tim Richardson
Sent: Sunday, February 25, 2018 9:29 PM
To: TS-590@groups.io
Subject: [TS-590] UPDATE Re: FSK Keying of TS-590SG
Just to give everyone who has commented a little update:
1. I located another serial card and installed it in my computer. It
gives me a full -/+12VDC swing on the data lines.
2. The optoisolators in my interface are not pulling the PTT and FSK
inputs of the rig low enough to work. When the optoisolator is turned
on, I am still seeing +0.54VDC on the ACC2 inputs to the rig.
3. I tried different values of current limiting resistors from 100Ω to
1.5KΩ on the inputs to the optoisolators with no change.
4. I checked my junk box for some NPN transistors and found none (I
could have sworn I had some 2N2222s), so I have a few on order for the
coming week. I plan to build the simple resistor/transistor interface
that many have suggested.
5. After I get FSK working, I do plan to also try AFSK. There seems to
be a spirited debate among many as to which is best. I have no doubt
that either method properly used can give good results so I want to find
out operationally which method I prefer.
My thanks to everyone who has taken the time to respond with your
comments and suggestions. I found them all very helpful.
73,
Tim WS4V
On 2/23/2018 2:49 PM, groupsrichart@gmail.com wrote:
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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