[Collins] R761 ARC-58 Receiver

[Jim Whartenby]

Dave
Schematic is found in the URC-32 manual on Nick England's site, 
see: https://www.navy-radio.com/xmtrs/urc32/NAV-Vol-1-tech-manual.PDF 
on page 5-105.  Same PTO is also used in the KWT-6.  The 70H13 uses a reactor to lock the PTO to the Reference Oscillator, the 70H13A uses a Varactor Diode to do the same, otherwise everything else should be unchanged.
I have never had a tube failure in a PTO so I suspect that there will no problems when firing it up.
Pin-out of PTO is as follows (assuming I didn't make a silly mistake following the circuit!)  <grin>
P1-1  115 vac heater neutral
P1-2  115 vac heater
P1-3  +28 VDC input to Zener diode.
P1-4  Common (ground)
P1-5  Zener diode output, used to fix the bias on the frequency and phase discriminator resistor string.
P1-6  Varactor bias from the frequency and phase descriminator.
P1-A  Oscillator amplifier output & B+ for V1
P1-B  6.3 vac tube filament
P1-C  N/C
P1-D  N/C
P1-E  130VDC B+ for V2 Oscillator 
P1-F  N/C
If you just want to verify PTO operation you can ignore connecting P1 pins 1, 2, 3, 5 & 6
Connect P1-A to B+ through an RFC to separate B+ from the 2 to 4 mc output signal.
Note that the internal switch S2 grounds the control grid of V1, the isolation amplifier, until the PTO reaches operating temperature which should take a few minutes so don't panic if there is no output when you first apply the 130 VDC B+.
If you need more help, feel free to contact me off list.
Jim
Logic: Method used to arrive at the wrong conclusion, with confidence.  Murphy

-----Original Message-----
From: Dave ZL3FJ <2c39a at silverbears.nz>
To: Collins at mailman.qth.net
Sent: Tue, Mar 1, 2022 9:57 pm
Subject: [Collins] R761 ARC-58 Receiver

Looking for data on the 70H13A module ex the above receiver. I was given
this  ex an estate recently but have no information other than the little I
have been able to find on the internet. I understand this is a permeability
tuned oscillator  assembly but would like a schematic and connection data to
run it up and test it.
 73
 Dave, ZL3FJ


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