[ARC5] PL-55 and PJ-068 type plugs with retaining rings inquiry

[Mike Hanz]

On 7/3/2013 8:51 PM, Jay Coward wrote:

> Ever notice on ARC-5 gear that key and mic jacks have extended threads on the outer sleeve? I have two plugs that fit the key jacks on several of the transmitter control boxes and MD-7 and can be secured with a threaded retaining ring.
>
>
>   One is marked B180207 and has a black plastic shell. The other is marked 275 and appears to be able to be soldered directly to a properly prepared shielded cable.
>
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> Can anyone elaborate on this? Obviously someone thought it important that these did not get inadvertently unplugged.

That's clearly the intent, Jay.  The RL-7 interphone manual shows eight 
of them in use, for the transmitter sidetone jack, two receivers, and 
the pilot's throttle switch.  Inexplicably, the microphone plug to the 
transmitter is not so equipped, not any of the station jack boxes.  The 
part number in the manual is NAF-C310572-1, which matches a few I have 
here for the RL-5 as well.  The NAF (Naval Air Facility) designation 
sorta implies a specialty version of something for Navy aircraft use - 
you don't see huge production numbers normally associated with them.

> So why are these uncommon?

Because there turned out to be few compelling applications for such 
cautious safeguards as time went by?  That's the only logical reason I 
can think of.  One would think that they would have received a standard 
Navy 5 digit number if the acquisition quantities became high enough, 
but there seems to be plenty of the more common NAF 215285-2 and NAF 
1136-1 plugs still around.

          73,
  - Mike  KC4TOS