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Re: [RTTY] [TS-590] UPDATE Re: FSK Keying of TS-590SG

To: TS-590@groups.io, KenwoodTS-590@yahoogroups.com, rtty@contesting.com, TS-590S@yahoogroups.com
Subject: Re: [RTTY] [TS-590] UPDATE Re: FSK Keying of TS-590SG
From: groupsrichart@gmail.com
Date: Thu, 1 Mar 2018 22:55:16 -0500
List-post: <mailto:rtty@contesting.com>
As Ulf DK5TX wrote, "I like the KISS approach (keep it simple, stupid)". Based on the overwhelming advice received to use a simple one resistor, one transistor interface for FSK and PTT, I ordered some 2N3904 transistors and 1K resistors. They arrived today and I just clipped a few leads together to test and it worked perfectly. With about 0.75V on the base of the transistor, the output pulled to a low of 0.02V and was able to key the PTT line and the FSK input with no problems. Tomorrow I will solder this up and package it so I can be back on RTTY!

Thanks to all of you who took the time to respond and offer input and suggestions.

Tnx es 73,

Tim WS4V


On 2/27/2018 12:06 AM, groupsrichart@gmail.com wrote:
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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