[MRCA] RCA AVT-111 Question

[D. Platt]

On 2/27/2014 2:02 PM, Ray Fantini wrote:
> AVR-20?, wasn't there some sort of old timey craziness about how you used HF to talk to the tower and the tower responded on LF? Maybe on the NDB? And where were you supposed to put those huge square boxes in your L3 Cub anyway? By the mid-fifties when the Cessna 150 came out it incorporated a modern style avionics bay so assume all the old HF AM junk was dead by then and VHF AM had taken over so that AVT/AVR stuff must have had a short life span back in the forties and maybe early fifties.
>
> Ray F
>
>
Ray,
You are correct.  There was a "tower common" frequency in the 3 or 5 MHz 
range that was used by the aircraft and received, typically, on a 
tunable LF receiver.  RCA, Heath, Harvey Wells, and a bunch of others 
made them. In the 50's, Narco came up with the venerable Superhomer 
VHT-( ).  It had 5-8 transmitter channels and a tunable VHF receiver 
with VOR converter.  It also had a "whistle tune" like the A.R.C. 
systems.  The military had a VHF "tower common" of 126.18 (hence all 
those crystals out there for that frequency).  Its all a matter of 
history after that.  Narco, King, Cessna, et al with the 90, then 180, 
360, and finally 720 channels.  A lot of radio equipment (and their 
manufacturers) have gone to pasture in the process!

Jeep - K3HVG