[Milsurplus] TBX-8 frequency calibrator

[Ray Fantini]

All real TBX transceivers, not including the eight with its fancy audio amplifier and oscillator use a signal 837 tube for the entire transmitter. 500 volts on the plate and 12 volts to light the tube and you go to town. Maybe the feedback current thru the crystal is so high that they had to use a huge crystal like that? Wonder how long an AF4K crystal would hold up in a TBX? Or perhaps it's just the manufacture liked that big round crystal holder. The same style crystal holder was also used in other pre war commercial and armature stuff. Other then that the early TBX was a neat radio in other way like using only  around 300 Ma of filament current and under 20 Ma @ 90 volts for the receiver it would run all day long on small batteries. The old 34 tubes were an incredible tube. I ran one from two D cell for the filament and ten 9 volt transistor batteries for a long time with no issues. The worst problem I recall was the broad tuning and the lack of AVC so in a net operation you had to ride the gain control I kind of miss not having one around for Dayton and other events. Sorry if I offended all the eight owners but once they fixed all the issues of the older series and introduced the eight just not the same appeal to me having a radio with modern headphone connectors, the ability to use a regular carbon microphone and no longer using a filament rheostat it's just not the same.
RF

-----Original Message-----
From: milsurplus-bounces at mailman.qth.net [mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of Mike Morrow
Sent: Wednesday, February 22, 2012 1:37 PM
To: milsurplus
Subject: Re: [Milsurplus] TBX-8 frequency calibrator

Rob wrote:

> Of course if you have a crystal in the calibrator, you could put it in 
> the transmitter and get the same result.

Well...it'll be a bit of a challenge to use a crystal for the nt-60133 calibrator (FT-243 holders) in the TBX transmitter, which uses (God only knows why) the large round heavy semi-unique nt-40024A crystal holders.