Commo basically operated on 4 levels. First, there was wire
telephone commo. We could call the firing batteries but it wasn't easy. We
connected to the 101st and 24th Corps Artillery, and with difficulty, Da Nang.
Mostly it was used within Headquarters Battery but they were also used at the
firing batteries pretty much the same way. Mostly we relied on FM radio to
communicate with the firing batteries. They were especially important to the
Fire Detection Center (FDC).
At the firing batteries, FDC would use them to talk to Forward Observers and
Aerial Observers, and then use their 312 telephone to talk to the gun pits. We
also had AM radio that was used mostly for teletype capability. AM had a longer
range but was dependent on a stable ionosphere. The AM could be unreliable. Both
AM and FM had secure capability by using a crypto unit. The problem was you had
to reset the “heart” of it every day. The heart was a plug in that had a whole
bunch of little wires with little plugs that kept breaking.
It was necessary to periodically deliver new codes, call signs and frequencies.
If a radioman lost his codebook in the heat of battle, we might have to replace
it with new codes to prevent the enemy from being able to use it. We were often
in conflict with the ARVNs over who could use what frequency.
There was a bunker with safes that stored codes, classified documents, etc. It
was someone’s job was to pull the pins on the safe destroyers if we were ever
The 83rd switchboard call sign was Heavyweight.