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

Thu Mar 1 22:55:16 EST 2018

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 at 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 at 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 at 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 at 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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