[GreenKeys] AN/UGC-136BX Rx and Tx connections

[Nick England]

*From my helpful hints page*

*https://www.navy-radio.com/tty/ugc136.htm
<https://www.navy-radio.com/tty/ugc136.htm>*
*DB25M connector* - Pin 1 for RXD, Pin 2 for TXD, Pin 24 for signal ground
- See page 8-5

So data from your TU is applied to pin 1 and ground. Data to your TU comes
from pin 2 and ground.
Or for testing, just connect pin 1 to pin 2.

Normal Mark is -5v, Space is +5v
There is an invert switch that will reverse this.
The invert switch is only sampled during power on.

Ignore pins 13, 14, 17, 18 unless you are installing aboard a warship and
connecting to some unknown equipment……..

Nick England K4NYW
Chapel Hill NC
www.navy-radio.com


On Sun, Feb 1, 2026 at 8:14 PM Fred Weksberg <VE3PIE at outlook.com> wrote:

> I am trying to get this connected – and hit a roadblock
>
> The receive +/- 5 volts goes into the back panel J2 connector. I am
> looking at the schematics but it is not clear to me which pin does what.
>
> The manual says:
>
>
>
> *                 J2 connector pin #*
>
> RxD1                   1                           for the Rx:  which is
> +5v, -5v, and GND ?
>
> RxD2                   13
>
> RxD3                   17
>
>
>
> TxD1                    2                          for the Tx:  which is
> +5v, -5v, and GND ?
>
> TxD2                    14
>
> TxD3                    18
>
>
>
> Can anyone help ?
>
>
>
> Thanks, Fred
>
> VE3WN / VE3PIE
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