[Milsurplus] TBS radios

[Ray Fantini]

Some thoughts about using the TBS radio system in the modern world,
though I would post it here too so everyone can point out the error of
my ways. This is in regards to using TBS radios on Ham bands today.
Ray Fantini KA3EKH

>From the early fifties on most if not all military and commercial AM
transmitters used audio bandwidth limiting (3 to 5 Kc) and peak limiting
to prevent over modulation. Most if not all the WW2 stuff just had a
plate modulator or the Navy favorite “suppressor modulation” that
relied on frequency limited microphones and response limited in
transformer design. I have a bad habit of referring to the old school
transmitters as wide band although what’s way more important is level
of modulation. If you drive modulation beyond 100 negative the
transmitter will produce spurious wide band noise. Any AM transmitter
will do this but with a TBS being just below the low band television
channels and with it lacking any type of output filtering it has the
real possibility of producing wide band noise that can interfere with
television reception. Additionally their exist the possibility of
generating interference in the low band LMRS service (30 to 50MHz)
although do not think anyone is still using that service with almost all
fire and police operations migrating to the 800 MHz band. Think the only
thing I may be saying here is when using the TBS stuff try to keep the
modulation set low so regardless how excited the people who talk on it
get they cant over modulate. Do they have any limiters installed in the
audio system feeding the radio systems? Also I think I have read that by
the fifties all the TBS equipment was not used within site of shore
because of the likelihood of TVI, not 100 % cretin but have to wonder if
their was any use of the  TBS equipment beyond the war.