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 <[email protected]> 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______________________________________________________________ GreenKeys mailing list Home: http://mailman.qth.net/mailman/listinfo/greenkeys Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected]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.htmlThis list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]