Aircraft Radio Corp. Type 12 aircraft radios use

[yahya]

Could our experts share the experiences of using the Aircraft Radio Corporation Type 12 series aircraft radios of the 1950s vintage please? I would like to learn how easy the VHF and UHF radios of this series could have been tuned while used on a military jet in the 1950s? It is known that the VHF ARC Type 12 radios were used eg. the on the early U-2.

The VHF and UHF ARC Type 12 radios used separate transmitters and receivers. The transmitters were crystal-controlled, while the receivers used the VFO, and had to be fine-tuned using a small crank on the control panel. My question is: how easy could the ARC Type 12 receiver's tuning be achieved in a fast flying military jet? Was it cumbersome? Were the radios reliable in terms of fast-tuning to a new frequency? What about the receiver frequency stability after numerous hours of flight at altitude? Note the ARC Type 12 was adopted as the AN/ARC-60 in the LF and VHF variations.

As a reference: a page from the U-2 flight handbook describing the receiver tuning procedure of the ARC Type 12 set.

Control heads of various ARC Type 12 VHF and UHF sets.

 

[merlin]

When you are kicking back at 900 MPH, enjoying the scenery, it is awful easy to be tuning a radio.
Only times you may have your hands full is takeoffs, landings, avoiding SAMs and such.
Those ancient ARC radios were like a brick outhouse and that stable.
In those old contelations, it would give flight engineers something to do besides glaring at all the instruments.

 

[yahya]

Hi Merlin, thanks for the reply. After all, I am not so sure if the ARC Type 12 sets were that easy to tune in a single seat aircraft. I've just checked that such radios were also used on the Cessna O-1 Bird Dog, where the control panel was oddly installed in the upper side of the cockpit (see below). I've never used or seen the ARC Type 12 radios in action and I wonder if the fine tuning of the receiver, which required first to preset the transmission channel, then to coarse tune the VFO, and, finally, to depress and move the small crank to find the loudest side tone in the headphones, was easy. That rather sounds a bit cumbersome than simple. The ARC Type 12 represented the 1930s/1940s technology, albeit with the more contemporary control panel with DZUS mounting screws. I wonder if vibration and the workload on a single pilot would make it difficult to tune these radios in real life scenarios. Also, I wonder about the frequency stability of the ARC Type 12.

The place where the ARC Type 12 control panels were installed on the Bird Dogs is shown below. I wonder how to depress and crank the fine tuning knob when flying solo.