RCA Voltohmyst with unknown socket/plug

[Ghinessey]

Can anyone tell me what the socket/plug is pictured below on the bottom row of connectors 2nd from the left?  I have never seen a Voltohmyst with this configuration.  It appears similar to a Model 198

[ataradov]

Can it be just a standard 1/4" audio jack?

[Ghinessey]

it appears to be a 4 prong socket of some sort

[ataradov]

it appears to be a 4 prong socket of some sort

Ok, I misread the question. I was talking about "DC VOLTS" connector.

That I have no idea.

[smbaker]

It looks like a miniature version of a jones plug. I have a couple Voltohmyst WV-77E here, but neither has a socket like that.

[Ghinessey]

Yes it does look like a cinch plug or jones I thought. But I was wondering what it was being used for. 

[Stray Electron]

  It's called a "Jones plug" and they come in all different kinds of configurations and numbers of pins.  Some of the old US military radios including the BC-348 (rear power connector) used them. I'm pretty sure that they were made by Cinch but I think other companies made them as well.  You don't see them that much any more but the VoltOhmyst is an old meter.

[TimFox]

The square "Jones" connector is not labeled on the front panel.  Is it a socket added by a previous owner?

[N2IXK]

Definitely looks like an "aftermarket" addition by a previous owner.  If I had to guess as to function, I would go with filament and B+ output for some kind of amplified AC detector probe.  Opening it up and tracing the connections would seem to be the way to go.

As previously mentioned, the generic name for those type connectors is a "Jones plug". Still available from Cinch (formerly Cinch-Jones), through all the usual distributors.