[Milsurplus] Original TBX radio

[Ray Fantini]

Ok, just pulled the trigger on the TBX-5 manual, don't know about the 7, only know that I have owned a 6 in the past and the 8 is a different animal. All of the old TBX series using the 34 tubes were an interesting radio with the low power drain and the like and don't remember but think the 34 tube may be something like a two volt filament so would be two batteries in series for getting the filament voltage at from what I recall was 300 or 330 Ma.
The other issue was that they used a special high output microphone with all the non-eight versions. Think I installed a one transistor amplifier inside of a T-17 to use it years ago but may end up building a small box to go between the microphone and the microphone input on the radio.
The next issue will be identifying the PL connectors on the front of the radio for building up the cables. Figure that with the radio being such low current drain in receive will use batteries for the receive function and throw together a small inverter for the +500 and +12 that can be run from something like a car battery. Have had a lot of success running things for prolonged period of time on a car battery, just using one was able to run as NCS for the 3886 WW2 net at Dayton last year with no issues, too bad I am receiving this radio too late for this year.

Ray F/KA3EKH



From: Robert Downs <wa5cab at cs.com>
Sent: Sunday, February 26, 2023 2:32 AM
To: Ray Fantini <RAFANTINI at salisbury.edu>; milsurplus at mailman.qth.net; mrca at mailman.qth.net; MMRCG at groups.io
Subject: RE: [Milsurplus] Original TBX radio


Ray,

I offer a reprint of the TBX-5 manual.  Go to wa5cab.com.  There is very little difference from TBX through TBX-6.

TBX-7 was to be the same as TBX-8 (no change to the transmitter but the receiver is nearly the same as in the BC-1306 (7-pin miniature tubes).  The order for TBX-7 was apparently  cancelled.  The only place that I have seen it mentioned is in the manual for the 12VDC vibrator power supply.

If you plan to run the receiver filaments off of parallel D-cells, don't use DuraCell.  Two or more in parallel get very hot very quickly.

Robert Downs

From: milsurplus-bounces at mailman.qth.net<mailto:milsurplus-bounces at mailman.qth.net> [mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of Ray Fantini
Sent: Friday, February 24, 2023 09:03
To: milsurplus at mailman.qth.net<mailto:milsurplus at mailman.qth.net>; mrca at mailman.qth.net<mailto:mrca at mailman.qth.net>; MMRCG at groups.io<mailto:MMRCG at groups.io>
Subject: [Milsurplus] Original TBX radio

I will soon be picking up a new to me Navy TBX transceiver. I did have a TBX-6 about twenty years back that I had operated at Dayton and a couple other events but traded that away years ago. Problem was way back then used all printed material so don't know how much of the old paperwork I will be able to locate
The new radio is a 1939 straight TBX (NOs-65704 16 Mar 1939) CG-43005 That's not a TBX-8, never wanted an eight and always liked the "Old School" design of the radios before that was interduce. I remember that the six that I had before used all 34 tubes along with something like a 1C4 in the receiver and the entire receiver only drew around fifteen or twenty mills at 90 volts during normal operation and was always amazed that any receiver can operate with that low a demand. Also, the non-eight all just have one tube in the transmitter that's suppressor modulated, think it was an 837
The new plan is to build up a battery pack with a couple D cells and a stack of nine-volt cells for supplying the 90, 1.5 and bias needed by the receiver and get that working first and then throw something together for the transmitter for the five hundred volts required for that.
The problem will be that I am now in need of a couple things, first the schematic for a TBX, any TBX up to the seven series will do but the schematic for the eight is of little to no use, have that anyway and I will need the correct name and identifier for the two power plugs on the front of the radio. Think they are all the same on all the TBX family.  I now have to come up with another set of plugs for the radio.
Somehow over the years this radio has lost its case, think that may be a huge issue in the future but for now not a big problem, kind of like the way they look when you operate them outside their case. I have an RCA AVR receiver and a old command set transmitter that I intend to be running for the WW2 3885 AM Net out in Dayton this year and the old RCA looks way cool with all its aluminum cans and tube shields exposed.

Ray F/KA3EKH

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/milsurplus/attachments/20230227/69d550a5/attachment.html>