[Milsurplus] Navy 5-wire handsets

Sun Jul 11 19:05:04 EDT 2021

Mmmm, my that is some tasty crow!
Yep, the T-827 connector does not have GND on pin D like all the other
xmtrs - it has +12v. And pin C from the mic output goes to ground through a
transformer winding. So the mic preamp gets the proper polarity supply
voltage.
So on the other rigs, PTT keys the transmitter by grounding (pin D) the key
line (pin E) and also grounding the + lead of the mic preamp.
But NOT on the T-827 - the PTT switch connects +12v to the key line and
also to the + lead of the mic preamp.

Thus endeth today's lesson on Navy handsets. Moral - just plug the damn
thing in and it'll work.....

Nick England K4NYW
www.navy-radio.com

On Sun, Jul 11, 2021 at 6:17 PM Nick England <navy.radio at gmail.com> wrote:

> 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
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>> --
>> Nick England K4NYW
>>
>> www.navy-radio.com
>>
>> --
>> Nick England K4NYW
>> www.navy-radio.com
>> ______________________________________________________________
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>> --
>> Nick England K4NYW
>> www.navy-radio.com
>> ______________________________________________________________
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