[ARC5] Command set installation

[Mike Morrow]

Glenn wrote:

> I was on FIFI a B-29 this weekend.
> The three command set receivers all had the same antenna jumpered 
> between sets and the two command set transmitters had the antenna 
> terminals jumpered together.
>
> Is this the way the radios would have been configured when the aircraft 
> was in use in the War?

In short...no.  A B-29 in the PTO would most likely have a pilot-operated BC-453-B range receiver as its **only** SCR-274-N gear.  The standard pilot-operated AN/ARC-3 8-channel VHF AM command set eliminated need for the rest of a SCR-274-N HF command set.

But assuming that fanciful SCR-274-N HF command set actually had been installed:
1.  The three receiver A posts would tie together and connect to the REC post on the BC-442-A antenna relay.
2.  The two transmitter A posts would tie together and connect to the TR post on the BC-442-A antenna relay.  NOTE:  If one of the transmitters is a BC-459-A (7.0-9.1 MHz), the HF command set antenna on a bomber would likely be too long to load properly for that transmitter's frequency range.  Its A post would connect to the lower C post on the BC-442-A.  The upper C post on the BC-442-A would connect to the TR terminal, along with the lead from the other transmitter.  This places a 50 uuf vacuum capacitor in series with the BC-459-A antenna circuit to electrically shorten the antenna.

> The three receivers were above the ART-13 and had remotes just a short 
> distance away above the receivers...

Just more fanciful arrangement.  An HF command set's operating controls would always be installed near the pilots, not the radio operator.

> ...and to the right of the receivers above the BC-348-M.

See the qrz.com page for KM4RC.  The radio gear has been selected and arranged to appeal to a ham operator of WWII USAAF gear without great regard to a realistic arrangement for a USAAF B-29.  There's no sign of the AN/ARC-3 VHF command set, a calibration book for the AN/ART-13A, or O-17A/ART-13A plus CU-25/ART-13 MF units.  A BC-461 trailing wire antenna control, the J-37 key, and the MONITOR/NORMAL netting switch seem to be omitted.  An anachronistic electronic key and Collins 180S-1 ham antenna tuner are present.  It's unlikely an old-design BC-348-M flew in a B-29.  The operator's desk would extend in front of the BC-348-*, not the T-47A/ART-13.

> The aircraft call is KM4RC.

That's the ham station call, not the aircraft call.

I don't understand going to all the trouble to install apparently working gear like this to make a ham-configured station (complete with display plaque and large call-sign on the T-47A) as opposed to a military-configured station.  With little more effort, an operable and historically-accurate representation could be made.

Mike / KK5F