[GreenKeys] CV-116 dual diversity RTTY converter hookup

[Harold Hallikainen]

It IS interesting. I think that they put the machine between the negative
end of the loop supply and ground so the machine would not have high
voltage on it unless the keyboard is open (assuming the keyboard is in
this loop). That improves safety.

While using the keying tube as the current regulator (and adjusting the
current by varying the screen voltage) is interesting, I don't think it is
a good idea if the loop voltage is high. Why dissipate all that power in
the keying tube when we could dissipate it in a resistor that will last a
lot longer than the tube? For a similar reason, I don't like the loop
current regulator in the TU-170 where the dissipation in the keying
transistor is high. However, the TU-170 has a pretty low loop voltage
(about 80 volts), so use of a resistor might allow too much variation in
loop current, but I suspect a resistor would have done fine.

Harold
https://w6iwi.org


On Wed, November 5, 2025 7:21 am, John, W9DDD wrote:
> Interesting approach, I'd never have thought of doing it that way.
>
>
> If there is more than one way to do something, the military will choose
> the more "elegant" way.
>
>
> On 11/4/2025 4:06 PM, Nick England via GreenKeys wrote:
>
>> Well - it appears a little more complicated than the simplified
>> diagram led me to believe - there is an internal loop supply with plus
>> connected to the 6AQ5 plates and minus to ground through the TTY. Loop
>> current is set by adjusting the 6AQ5 screen voltage,
>>
>> Nick England K4NYW
>> Chapel Hill NC
>> www.navy-radio.com
>>
>> On Tue, Nov 4, 2025 at 4:03 PM Nick England <nick at navy-radio.com>
>> wrote:
>>
>>> I've had a CV-116/URR sitting around here for a long time and am
>>> thinking about trying it out. The CV-116 is made for diversity
>>> reception and is fed via IF signals from two R-390A receivers
>>> connected to different antennas. It has 45 tubes (plus 2 motors for
>>> AFC control) - what could possibly go wrong?
>>>
>>>
>>> Is anyone using one of these? It looks like the TTY interface is
>>> pretty straightforward with an external 60ma loop keyed to ground via a
>>> pair of 6AQ5 tubes.
>>>
>>> BUT -  the manual refers to needing an external "control unit" - what
>>>  does it mean by that?? Is it just a connector adapter? or? "Because
>>> the teletypewriter output connection of the converter does not match
>>> the input connection to a standard teletypewriter printer, an
>>> intermediate control unit is required between the converter and the
>>> teletypewriter printer."
>>>
>>> Nick England K4NYW
>>> Chapel Hill NC
>>> www.navy-radio.com
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>
> --
> ---
> ----
> The above comments or recommendations are SWAG. Use at your own risk.
>
>
> John, W9DDD
>
>
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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
>>>>
>
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