[ARC5] arc5

[Mike Morrow]

> ...the ARC5 and SCR274 tx racks have different connectors...

And different wiring to each pin.

> ...the rx racks are like the rxs identical.

Well...the SCR-274-N (and ARA) receivers are certainly *not*
identical to equivalent AN/ARC-5 receivers, especially the
R-23* or R-24/ARC-5.  These two have a special AF output
from the 12A6 cathode that is designed for the MX-19 interface
to the AN/ARN-9 ILS.  These two also have loop connections.
All AN/ARC-5 receivers have real AGC.  Most R-25, 26, 27/ARC-5
units have LO stability mods.  AF output impedance is low.

None of the above apply to the SCR-274-N except B models can
be wired for high or low Z AF output.  An ARA unit is identical
to the 274-N except that it is low Z AF only.

It is better to substitute an AN/ARC-5 receiver in one of the
other two earlier systems than the reverse.

The racks are very close...identical electrically.  But
mechanically, the AN/ARC-5 racks have small loop/tabs
stamped into the metal near the front A - B select switch 
to anchor the lock-wire for this switch.

As far as transmitter components go, the *only* two
AN/ARC-5 components that are *electrically*
interchangeable with equivalents from the earlier
systems are the dynamotor and the antenna relay.

Mike / KK5F