[Milsurplus] Re: [MRCA] TBS radios

[Rob Flory]

TBS was absolutely used into the 50s. 

Rob Flory

-----Original Message-----
>From: Ray Fantini <rafantini at salisbury.edu>
>Sent: Jan 4, 2008 10:58 AM
>To: milsurplus at mailman.qth.net, mrca at mailman.qth.net
>Subject: [MRCA] TBS radios
>
>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.
>
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