Ok great information! I’ll get this all wired up this weekend!
From: Robert Downs <[email protected]>
Sent: Friday, November 12, 2021 3:13 AM
To: W2HX <[email protected]>; [email protected]
Subject: RE: [Milsurplus] LS-3 question
Eugene,
There is no smaller diameter 2-circuit plug of the same diameter as the WW-II or earlier PL-68 or the Korean War or later PJ-068B. The LS-3 that you have
has the correct 3-circuit jack on it. If your BC-312 has a 2-circuit 1/4” jack at the Speaker 2nd Audio position, then some numb-nuts swapped it. And I hope that he at least had enough sense to either remove the wire going from the original jack
back to +12VDC or at least to insulate the bare end of it. The Phones 1st Audio jack, on the other hand, has the 1/4” dia. 2-circuit jack to operate a Headset. But it wouldn’t run the LS-3 anyway.
The reason behind all of this is two-fold. Second, if someone is monitoring a circuit with Hi-Z headsets and someone else jacks in an LS-3, the headset(s)
go dead or at least much quieter. But first, the BC-312 was the first of the four similar sets developed. When development began, the standard loudspeaker that it was to use was an electro-dynamic or field-coil type. Then someone else invented Alnico and
the LS-3 and other speakers quickly became the standard. It wasn’t until near the end of BC-312/314 production that the 12VDC wire was eliminated. The BC-342/344, however, never had the third wire installed as in most cases, 12VDC was not available. But
they did have the JK-33 for Speaker-2nd Audio. Just like the BC-312/314. And did use a 3-wire cable to connect the LS-3.
Robert Downs
From:
[email protected] [mailto:[email protected]]
On Behalf Of W2HX
Sent: Thursday, November 11, 2021 09:54
To: milsurplus@mailman
Subject: [Milsurplus] LS-3 question
Hi all,
I have an LS-3 that I plan to connect to my BC-312. The 312 loudspeaker jack fits a PJ-055B (1/4”), however the LS-3 has a smaller diameter jack. A PJ-068 fits fine into the LS-3, however the PJ-068 is a 3 pole connector and I only need
a two pole. What is the right designation for a plug with the same diameter as the smaller PJ-068 but with only two poles? Or was the LS-3 expected to just use two of the three poles of a PL-068?
73 Eugene W2HX
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