[ARC5] "Retaining" plugs

[Mike Everette]

I've seen a number of the PL-68/PJ-068 connectors with threads protruding beyond the plastic shell, on a couple of different types of microphones.  Off the top of my head I don't remember any PL-55/PJ-055 crossing my path that have the threads exposed but there may well have been.  At a hamfest a couple of years ago I bought a bunch of "new" headset extension cords like the CD-307, I'll look them over more closely.

Truth be told, I never thought of the exposed threads being for a retaining device; I just thought that for some reason the shells didn't screw all the way on (duuuuh).  I've either repaired or installed numerous of these plugs in ham apps and gen-av avionics, so yes, I've seen a few.

As an aside, Motorola uses a similar idea with their "audio adapter" devices employed with current hand held radios, when headsets or earpieces are in use.  The plugs are 1/8 inch instead of 1/4; but they do have some exposed threads to lock the cord into the adapter, which is attached to the side of the radio (that's what the exposed flush gold plated terminals on the side are for, in addition to programming-cable connection).  

Back to the matter of WW2 gear, I would think that oxidation or corrosion of the brass PL-55/68 etc especially in humid climates would have been a far more serious problem than plugs popping out, though.  I've cleaned quite a few myself when audio, either receive or transmit, got scratchy or intermittent.

73

Mike
W4DSE