[ARC5] tuning knobs (and local controls)

[Mike Morrow]

Jack wrote:

>Another rare item for a locally controlled receiver is the
>PL-192 plug for the receiver rack. This is a jumper plug for
>the receiver rack that completes the +28 volt supply line for
>on-off switching. There is an MX-something equivalent for the
>AN/ARC-5 as well...

Excellent point!  How could I have forgotten that?  The wired
plug for the SCR-274-N is indeed rare.  In all my years, I've
come across just one PL-192, and I got that from A.J. Link.

These local control plugs make up the LV power connection from
pin 1 to 6 on the back top of receiver rack, which normally would
be made up at the remote control box.

The official AN/ARC-5 equivalent is the "A.R.C. 6787 Wired Plug".
I've never seen one.  Another plug which could be used is the
MX-2/ARR-2 that Jack refers to.  It is wired like the A.R.C. 6787,
plus it has a connection between pins 2 and 8 to connect receiver
audio output to audio bus A.  This was required for AN/ARR-2
installations using the early MT-7/ARR-2 single receiver rack,
which does NOT have an audio bus A / bus B select switch.  (That
was later added to the MT-7A.)  There are a lot of MX-2/ARR-2 plugs
around because they were used every place that the AN/ARR-2 was
was installed.  Since all AN/ARR-2 and AN/ARC-5 racks other than
the old MT-7 have audio bus switches on the rack, the AN/ARC-5
manuals say that the connection between pin 2 and 8 should be
lifted on the MX-2.  Thus it becomes electrically identical to
the A.R.C. 6787.

Mike / KK5F