Hello Mark,

In the images of your R-23, five potted capacitors are leaking wax. Running at lower HT will not delay onset of problems; better to replace with post-WWII potted capacitors (rated for 400 V) where a different insulant was used that did not leak out. Many years ago, I published a technique for rebuilding potted capacitors with modern components. I’ll see if I can find it.

Some Command receivers came from the factory wired for 12 to 14 Vdc for use in aircraft with 12 V system, such as the British A V Roe aircraft, the PBY, and, as I recall, the Harvard trainer. Such receivers had an ‘X’ added to the nomenclature plate. The DM-53AZ dynamotor was used instead of the DM-32. As I recall, the intercom audio change-over relays in the mounting racks worked OK on 12 V.

PVC insulated wiring came late in WWII when DuPont sort of learned how to stablise PVC. Unfortunately, many years passed before true stablisation occurred. Post WWII, house mains wiring shifted from cotton covered, rubber-insulated cables to early PVC – now, that PVC is turning to mush giving a boon to electrical trades for rewiring houses.

As I recall from reading the operating instructions, that capacitor (C-30) insulated from the chassis was for feeding audio through the front bucket connector to ground personnel guiding the aircraft to a parking area.

If you seek 85 kHz IFTs, I can help.

73 de Brian, VK2GCE

From: [email protected] [mailto:[email protected]] On Behalf Of Mark K3MSB
Sent: Saturday, 23 December 2023 9:26 AM
To: Mike Kana
Cc: ARC5
Subject: Re: [ARC5] AN/ARC-5 R-23 Question

Hi Mike

Yes, it sounds a lot like mine.   Photo attached.

Mark K3MSB

On Fri, Dec 22, 2023 at 12:15 AM Mike Kana <[email protected]> wrote:

I have a similar R23 that had plastic coated wires added and a few remaining cloth wires. One flower pot cap has a black insulating base but the cap shell has a solder lug and a black wire (to ground?)
The front had alameda NAS stenciled on the front and also a “test” identifier.
It was partially modified when I got it - missing the dynamotor shock mounts and one of the if coils.
I did replace a couple leaking flower pot caps in an effort to make operational.
Does this sound similar to yours?
Thx 73
Mike

Warning!  This is transmitted over a non secure medium

> On Dec 21, 2023, at 8:30 PM, Mark K3MSB <[email protected]> wrote:
>
>
> Back in August I picked up an R-23 Navigation receiver.   I was delighted to find this as I do NDB hunting and wanted to play with this receiver on the LF band a bit this winter.
>
> Externally the radio was in nice shape with original connector on the back.   I removed the bottom cover and immediately saw modern wiring.  Lots of it.   Oh crud....
>
> The first thing I did was to check the filaments and, as expected, they were wired for 12/14 volts.  No problem there.
>
> The thing about the new wiring was that is was very nicely done, not your typical hack job you find in these radios.     I did some preliminary circuit tracing and it looks like some of the new wiring just replaced the old wires.     
>
> I am using AN 16-30ARC-2 dated 15 Dec 1954 as my reference manual.   It is of course a copy from the web.
>
> I note in my R-23 that C-30 is insulated from the chassis, and the capacitor case goes through a 100K resistor to ground.
>
> In AN 1630ARC-2, Figure 6-3 (page 56) shows the underside of the radio.   It looks like C-30 is raised from the chassis – but since my manual is a copy,  all I see is black in that area.   Can any of you verify it is lifted / insulated from the chassis?
>
> Also, at the top of C-30 are 4 resistors (R4, R9, R11, and R-27).  My R-23 has a 5th resistor in that group, and that 5th resistor is the 100K that goes from the case of C-30 to ground.    The 5th resistor is original – It wasn't added later.
>
> My Figure 6-3 says it's of an early production set.  The schematics in the manual show the case of C-30 directly grounded, but I assume that is also for an early unit.  If any of  you have a different copy of the manual, can you check the schematic for this?
>
> Thank you & 73
>
> Mark K3MSB
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