[ARC5] SG Keying of ARC-5 Tx

[Mike Morrow]

Bob wrote:

> The main use of the CW key was getting a DF STEAR.

As a historical note:  The first of the 27 different sets in the SCR-A*-183/-283 series could NOT transmit pure A1 or CW.  It is the only set in the entire series that was incapable of A1 transmission.

The 1932 A.R.C.-made SCR-AA-183 transmitter BC-AA-180 operated only in KEY (A2) or MIC (A3) modes.  Its control box BC-AA-182 has a select switch for REC(eive), KEY(A2), MIC(A3), with the key on CB top.  Because the set was intended to normally use KEY rather than MIC, the KEY position was the first reachsd when leaving the REC position.  Doubtless, most transmisiions were short and coded on A2.  The associated receiver BC-AA-179 was designed for modulated A2 and A3 signals.

There are no relays in the system, so there was no PTT capability in MIC.  Separate antennas were required for transmitter and receiver.

It was state of the art in aircraft command sets, 84 years ago.

Mike / KK5F