[GreenKeys] Anyone need a loaner 28-TD (100-wpm to rs232)?

[Lester.veenstra K1YCM]

RGR Thanks 

gil smith wrote:

> Hi Lester:
>
> The 28TD got converted to 232 with just an ac adapter, a transistor, 
> and a resistor.  Take a peek at:
>
> http://www.baudot.net/tty-232/my-28TD-d.jpg
> ...to...
> http://www.baudot.net/tty-232/my-28TD-h.jpg
>
> I removed the original connector/bracket inside, and was able to 
> squeeze a 12VDC adapter in it's place.  I connected the adapter to 
> switched ac power using the end of an extension cord.  The 232 output 
> line simply has a 2.7K pulldown resistor to ground (for the mark 
> state), and a 2N4126 PNP transistor to drive it up to 12VDC (for the 
> space state).  The tempest contacts are SPDT, and the filter board 
> provides series resistance for base drive -- so I just connected the 
> base of the pnp to the appropriate side of the switch.
>
> The RS-232 mark level is technically supposed to be below -5VDC, but 
> virtually every 232 input chip on a pc will accept ground as a valid 
> mark (negative) state.
>
> gil
>
> At 04:37 AM 2/16/2005, you wrote:
>
>> Sounds like just the thing !
>> What was the mod to get rs-232 out of the lowlevel box?
>>
>> gil smith wrote:
>>
>>> Hi Lester:
>>>
>>> I have a standalone 28TD I could loan to you for a while.  It is 
>>> small; maybe 20 pounds.  It was a tempest unit with low-voltage 
>>> contacts, so could not be used on a standard high-volt loop.
>>>
>>> I modified it to send rs232 directly.  It just has two pigtail 
>>> connectors:  one for an ac power cord and one DB9F for connection to 
>>> a PC via a straight cable.  The TD rums at 100-wpm, so tape reads 
>>> are a bit faster than you would get on a model 14 at 60-wpm.
>>
>
>
>
> Vaux Electronics, Inc.
> 480-354-5556
> (fax: 480-354-5558)
> www.vauxelectronics.com
>
>
>

-- 
Lester Veenstra
Senior Engineering Program Manager
Intelsat General
6550 Rock Springs Drive, Suite 450
Bethesda Maryland, 20817
+1-301-571-1212
e-mail: lester.veenstra at intelsatgeneral.com