How were the radios used by different elements and in different tours?
There were men using the radios vs those repairing them. Both may be able to help with the discussion from different perspectives.
FM (Frequency Modulation), VHF (Very High Frequency, UHF (Ultra High Frequency), ADF (Automatic Direction Finder) Radio
Tom Fleming: This is a good topic. It fills in an aspect of our use of critical equipment by various elements of 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 previous 1968 period was the Lt Scout OH-23Gs. They communicated on FM between each other because their only other radio was left on the Universal Emergency Frequency 243Mhz (UHF Guard), so that in case of in flight emergency they could be located by other aircraft for extraction.
The FM radio in UH-1/AH-1 had an homing capability giving the helicopter could home in on any FM radio.
The UHF radio in all other helicopters was used for air to air and air to ground (Troop Operations) air traffic control and inflight emergency.
VHF Installed in UH-1s for navigation (OMNI & ILS), but used for inflight communications principally by gun ships via a VHF broadcast capability via a limited number of crystal frequencys transmitter.
HF. No experience during my tour
Pat Eastes: How about FM homing? Seems like I can remember using it to find Cu Chi during a night mission in a monsoon when we were seriously IFR (Instrument Flight Rules or flying blind)
Frank Dillon: I figure the users have the most knowledge why/how a specific radio was used. 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: AFVN (American Forces Vietnam Network) “Good morning Vietnam” broadcasts.
Choppers could pick it up on the AN/ARN 83 ADF radio. My memory is that Slicks were the only ones that had those. IDK. Snakes may have had them? Loaches too maybe? I don’t recall them being an issue except when someone lost their “entertainment”. My perception is that the ADF function was never used.
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 Area of Operation 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.