[GreenKeys] HAL RVD-1002

[Eric Moore]

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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