How and where the radios were used is the discussion
………………………………………………………………………………………………………………………………………We tend to throw the radio terminology around quite loosly making it hard for our viewers to really understand which terms mean what, how did the devices and instruments for them change over time and by aircraft, how were the same radios used in different ways by different elements of the Centaurs, and so on.
Tell us what you remember about FM. Automatic Direction Finder (ADF), UHF, VHF, HF, Omni, ILS, GCA, American Forces Vietnam Network (AFVN), Guard, 243.0, Intercom, Air Traffic Control (ATC), non-directional beacon (NDB), etc
Tom Fleming: This is a good topic. It fills in an aspect of our use of critical equipment by various elements of the Centaurs.
The FM radio was the tool used to talk to individuals on the ground, e.g. artillery warning nets, artillery firing units, ground forces (Comand and Control HQs, Div, Bde, Bn/Sqdn, Co/Trp/Btry, Aero Rifles, LRRP/ etc.
One anomaly in the 1968 period was the Light Scout OH-23Gs. They communicated on FM between each other because their only other radio was left on the universal emergency frequency 243.0 so that in case of in flight emergency they could be located by other aircraft for extraction.
The FM (Frequency Modulation) radio in UH-1/AH-1 had an homing capability giving the helicopter could home in on any FM radio.
The UHF (Ultra High Frequency) radio in all other helicopters was used for air to air and air to ground (Troop Operations) air traffic control and inflight emergency.
VHF (Very High Frequency) Installed in UH-1s for navigation (OMNI & ILS), but used for inflight communications principally by gunships via a VHF broadcast capability via a limited number of crystal frequencys transmitter.
HF (High Frequency). No experience during my tour
One use of AFVN was that the ADF (Automatic Direction Finder) could home on it. If you flew in a local area that you knew the relationship of the AFVN transmitter and your home base and other features that were fixed like Nui Ba Din mountain, it could be useful in marginal weather as a navigation aide.
Pat Eastes: How about FM homing? Seems like I can remember using it to find CuChi during a night mission in a monsoon when we were seriously IFR.
Frank Dillon: My job was to keep them working without knowledge of why one or another was used.
That said, FM was used to talk to ground troops because the PRC/77 was an FM.
I never saw an HF, but I reckon they were used to catch a skip at night and talk to the US.
Carl Betsill: Concerning HF radios, I discussed what I know about them in the avionics section. Only used by higher echelon. ADF was used very little for actual navigation by the time I arrived in 71. All aircraft had it as I recall. It was old technology. Originally there would have been continuously broadcasting beckons that allowed the pilot to tune in and adjust his heading to that beacon. I knew of no operating beacons in our AO in 71. That said, in an emergency, the radio would allow the pilot to fly toward any continuous broadcast signal in the frequency range of the radio. For example if there was a entertainment broadcast station at Chu Chi, it would have been possible to fly to it. There may have even been a broadcast beacon earlier in the war.