[Milsurplus] Navy 5-wire handsets

Sun Jul 11 18:17:36 EDT 2021

Oops my bad - the URC-9 mike line (pin C) is indeed driven by the -11v bias
supply through a 220 ohm resistor and the mic xfmr primary. The diagram I
was looking at had "+26.5" written nearby and I missed the "-11" that
really goes with that line. (n.b. +26.5 is used for relays)
Now I need to go look at the T-827 book again to see if I goofed there as
well.

I wonder if crow tastes better with ketchup or Heinz 57 ???
Nick England K4NYW
www.navy-radio.com

On Sun, Jul 11, 2021 at 5:32 PM Jim Whartenby via Milsurplus <
milsurplus at mailman.qth.net> wrote:

> I don't  know much about the URC-9 other then it is a derivative of the
> VRC-24 and by extension, the TRC-68.  I worked on the TRC-68 some 50 years
> ago.  My URC-9 manual went to Danial a few weeks ago along with a URC-9 R/T
> unit.  I have been using the VRC-24 / TRC-68 manual pdf found online so I
> am having some trouble following circuit connections that disappear from
> time to time as I follow it over two pages of schematics.
>
> There is a J15 on the mainframe which connects to a jumper plug P2 which
> can be inserted into J15 in one of two ways.  One configures the R/T unit
> as a VRC-24 and when inserted the other way configures the R/T unit as a
> TRC-68.  I suspect that some of this re-configuration is due to the use of
> either a dynamotor in the VRC-24 or the AC power supply in the TRC-68.
>
> In the VRC-24 configuration, -30 volts is applied to the microphone input
> line via R-817 (150 0hms) and R-604 (1k) from the -30 volts from the
> dynamotor.  It could very well be -12 volts when the microphone is keyed
> but I haven't bothered to calculate voltage drops.
>
> I assume that the TRC-68 is the same but that the -30 volts is supplied
> from the AC power supply.  Not really sure since I again have this problem
> of tracing lines that become transparent in places over two fold out pages
> of schematics.  If there is a J15 on the URC-9 main frame then I am quite
> confident that there is no difference between the VRC-24 / TRC-68 and the
> URC-9 other then a new metal casting of the front panel.
>
> So I don't see where +12 volts is available in the URC-9, there should
> only be heater voltages, +125 VDC, +300 VDC and -30 VDC bias.  Or do I need
> a better schematic?
> Jim
>
> Too much agreement kills a chat.  E. Cleaver
> <https://www.brainyquote.com/authors/eldridge-cleaver-quotes>
>
>
> -----Original Message-----
> From: Nick England <navy.radio at gmail.com>
> To: Jim Whartenby <old_radio at aol.com>
> Sent: Sun, Jul 11, 2021 11:46 am
> Subject: Re: [Milsurplus] Navy 5-wire handsets
>
> Not that I have found. Instructions for repair were “discard and replace
> entire mic cartridge”.
>
> On Sun, Jul 11, 2021 at 12:37 PM Jim Whartenby via Milsurplus <
> milsurplus at mailman.qth.net> wrote:
>
> Nick
> Does a "proper" schematic for the H-169/U exist?
>
> Jim
>
> Too much agreement kills a chat.  E. Cleaver
> <https://www.brainyquote.com/authors/eldridge-cleaver-quotes>
>
>
> -----Original Message-----
> From: Nick England <navy.radio at gmail.com>
> To: Jim Whartenby <old_radio at aol.com>
> Sent: Sun, Jul 11, 2021 7:39 am
> Subject: Re: [Milsurplus] Navy 5-wire handsets
>
> No reference to switching element leads.
> Nick.
>
> On Sun, Jul 11, 2021 at 8:34 AM Nick England <navy.radio at gmail.com> wrote:
>
> Now I am even more puzzled!
> In the transmitter Pin D is ground and pin C is the audio line (-12v
> through xfmr primary).
>
>
> On Sun, Jul 11, 2021 at 1:53 AM Jim Whartenby via Milsurplus <
> milsurplus at mailman.qth.net> wrote:
>
> Nick and Danial
>
> Here is the schematic I made of the H-169/U perhaps 15 years ago when I
> reworked W5OR's URC-32s.  I couldn't find any marking on the NPN transistor
> and the capacitor on it's base is perhaps 27 uF, can't read my own
> handwriting, 77 uF doesn't sound right!  Don't remember if I calculated
> the voltages shown or measured them.
>
> It looks like the diode is there to prevent a reverse bias condition.
> Perhaps there is an obscure reference to reverse the connections to the
> circuit board underneath the microphone element or in the connector for use
> with some equipment?
>
> Enjoy!,
> Jim
>
> Too much agreement kills a chat.  E. Cleaver
> <https://www.brainyquote.com/authors/eldridge-cleaver-quotes>
>
>
> -----Original Message-----
> From: Daniel Jones <djones at k6yic.com>
> To: Nick England <navy.radio at gmail.com>
> Cc: Milsurplus at mailman.qth.net
> Sent: Sat, Jul 10, 2021 9:03 pm
> Subject: Re: [Milsurplus] Navy 5-wire handsets
>
> I too am interested in this topic as I am dealing with this issue on a
> URC-9.   Nick was nice enough to supply a good handset but why the unusual
> change in polarity?
>
> Plus on the flip side I am only dealing with a URC-9 set, I wouldn’t mind
> messing around with a SRT-14 should anyone have on excess to there needs on
> the west coast…..
>
> Daniel
> K6YIC
>
> Sent from my iPhone
>
> On Jul 10, 2021, at 18:48, Nick England <navy.radio at gmail.com> wrote:
>
> 
> Looking at post-WW2 transmitters and handsets:
> The SRT-14 and URT-2 series of AM transmitters supply -12V through a xfmr
> primary to pin C for a carbon mic to ground (pin D) in the standard Navy
> Type 51007 handset
> The URC-32 SSB xcvr does the same.
> BUT...
> The URC-9 supplies +12v through the xfmr primary to pin C
> The T-827 exciter for WRC-1, URT-23, etc also supplies +12v
>
> Polarity obviously doesn't matter with a carbon mic in the handset, BUT....
> in 1960, the standard 51007 handset was updated to 51007A by replacing the
> carbon mic cartridge with a noise-cancelling cartridge with dynamic mic
> plus transistor amp.
> https://www.navy-radio.com/xmtrs/handsets/handset-51007a-spec-11.JPG
> The ubiquitous H-169 handset replaced the 51007 and has the same circuit.
>
> So why does the transistorized mic work with both + and - supplies?
> In addition to cautions to respect polarity, the mic cartridges in these
> handsets are marked + and - with - going to pin C.
> OK, you can put in a diode bridge so that either polarity will work, but
> then why the caution about respecting polarity? The 51007-A field change
> does say that the new mic cartridge includes protective circuitry in the
> event of reverse polarity but still cautions that it must be operated with
> correct polarity....
> " The transistor preamplifier is operated from the negative 12 volt d.c.
> power normally supplied from the associated control unit or transmitter.
> The circuitry contains protective provisions in the event of the
> application of 12 volts direct current with a reverse polarity. When a unit
> becomes defective, it must first be assured that a 12-volt direct current
> of proper polarity has been applied; and if so, the unit must be discarded."
>
> I seem to missing something somewhere. O exalted ones, this poor
> grasshopper seeks enlightenment........
>
> Cheers,
> Nick England K4NYW
> www.navy-radio.com
> ______________________________________________________________
> Milsurplus mailing list
> Home: http://mailman.qth.net/mailman/listinfo/milsurplus
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Milsurplus at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
> ______________________________________________________________
> Milsurplus mailing list
> Home: http://mailman.qth.net/mailman/listinfo/milsurplus
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Milsurplus at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> ______________________________________________________________
> Milsurplus mailing list
> Home: http://mailman.qth.net/mailman/listinfo/milsurplus
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Milsurplus at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
> --
> Nick England K4NYW
>
> www.navy-radio.com
>
> --
> Nick England K4NYW
> www.navy-radio.com
> ______________________________________________________________
> Milsurplus mailing list
> Home: http://mailman.qth.net/mailman/listinfo/milsurplus
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Milsurplus at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
> --
> Nick England K4NYW
> www.navy-radio.com
> ______________________________________________________________
> Milsurplus mailing list
> Home: http://mailman.qth.net/mailman/listinfo/milsurplus
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Milsurplus at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/milsurplus/attachments/20210711/1d97d658/attachment-0001.html>