[GreenKeys] HAL RVD-1002

[William Wuttke]

I had to make a simple loop to RS-232 converter, such as suggested by
Harold, to use my M28ASR with both my HAL ST-8000 and ST-8000A which use
Baudot over RS-232 and have no loop interface. Almost all TU's except for
maybe the earliest provide an RS-232 interface.
Bill

On Sat, Dec 7, 2024 at 11:13 AM Eric Moore <mooreericnyc at gmail.com> wrote:

> Receive only, I have never seen baudot over RS232.
>
> I will probably set the RVD-1002 to the side for a bit and focus on my
> iron horse, TD, and 14 printer. Just a bummer because I wanted to use the
> RVD to basically test the baudot char gen and TD I have, but both are
> current loop devices.
>
> -Eric
>
> On Sat, Dec 7, 2024, 12:46 PM Harold Hallikainen via GreenKeys <
> greenkeys at mailman.qth.net> wrote:
>
>> Those are RS232 levels. I designed a loop to TTL interface (
>> https://w6iwi.org/rtty/tu300/Tu300LoopDriverSchematic.pdf ) that fits in
>> a
>> USB dongle case to plug into the back of a Flesher TU-170A or TU-300. TTL
>> to RS232 conversion could be done with an MC1488 (transmit) and MC1489
>> (receive) or a MAX232 (
>> https://www.analog.com/en/products/max232.html#part-details ) which
>> includes charge pumps to generate the higher positive and negative
>> voltages.
>>
>> Is the RVD-1002 transmit and receive, or, perhaps, receive only? If
>> receive only, U1 in the above linked schematic could pull the RS232 line
>> towards -12V when in mark, and a pull-up resistor could pull it towards
>> +12V when in space. That would be a minimum parts count (the ideal design
>> has zero parts) design, I think. In the above linked schematic, Q1 acts as
>> an inverter taking the mark low output of U1 and converting it to mark
>> high going into the TU-170. For RS232, you would not need this inversion.
>>
>> To key the loop from RS232, K1 could be used with pin 1 grounded, and the
>> RS232 transmit line driving U1 through a current limit resistor.
>>
>> Good luck!
>>
>> Harold
>> https://w6iwi.org
>>
>>
>> On Sat, December 7, 2024 11:23 am, Eric Moore wrote:
>> > Hello! I am trying to set up a HAL RVD-102 with my TD.
>> >
>> > The RVD-102 takes a mark bit of -5 to -15V and a space bit of +5 to +15V
>> >
>> > I do not have the optional loop interface. I suppose to use this with my
>> > model 14 TD I would need to build a circuit to take 100V/0V and convert
>> to
>> > 10V/-10V or similar, correct? (AKA low voltage serial)
>> >
>> > Also, I have a Xitex UDT-170, but no manual. Anyone seen one before?
>> >
>> > Thank you,
>> >
>> > -Eric
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>> >>> Jordan Spencer Cunningham's GreenKeys Search Tool:
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>> >>> 2002-to-present greenkeys archive:
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>> >>> 1998-to-2001 greenkeys archive:
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>>
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> ______________________________________________________________
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>
> >>> Jordan Spencer Cunningham's GreenKeys Search Tool:
> https://teletype.net/gksearch
> >>> 2002-to-present greenkeys archive:
> http://mailman.qth.net/pipermail/greenkeys/
> >>> 1998-to-2001 greenkeys archive:
> http://mailman.qth.net/archive/greenkeys/greenkeys.html
> >>> Randy Guttery's 2001-to-2009 GreenKeys Search Tool:
> http://comcents.com/tty/greenkeyssearch.html
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
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