TBY – USMC and Navy Transmitter-Receiver

The TBY as used by the USMC and Navy during WWII. This particular example is an early TBY-2, Type CRI-43007 and was built by Colonial under a contract dated 8 January 1941. It is a late 1930’s design for the U.S. Navy and at the time was reportedly better than earlier Army gear of the same, or earlier vintage, namely the SCR-194/195. The TBY morphed up to the TBY-8 series, incorporating many incremental improvements to improve water resistance, a stronger antenna etc.
When carried in its canvas backpack it was slightly splash proof but still not up to the task of amphibious landings unless the individual operators provided additional waterproofing. This era was before MFP – Moisture Fungus Proofing – so I would imagine their life expectancy in a humid Pacific island jungle would be rather short before rain, humidity, fungus, rust, sand and salt water corrosion destroyed them.

It is known that they were used aboard PT boats as a backup to the TCS sets. After action reports from PT Boat squadrons in the South Pacific / Rendova AOR indicate that TCS comms between the boats and from the boats to base were generally “satisfactory”. Enemy jamming was noted and was effective at times on 3785 kc, one of the operational frequencies in use. When HF radio problems occurred, the reports noted that TBY’s were used to good effect between boats. However weak batteries, beyond their “use by” dates, were a constant problem. Reference 54.

Operating over a frequency range of 28 – 80 MC with about a half-watt output, it provided short range CW and AM voice signals. (I wonder how much CW was used with these sets.) Between assault troops on the beach and a supporting destroyer I would guess its transmit range would be a few thousand yards. In the jungle, well, not much. The frequency stability was rather poor but the regenerative receiver was relatively wide so they apparently worked reasonably well together – with significant operator training and experience. Using what is essentially a modulated oscillator in the transmitter, they also produced significant frequency modulation as well, but what the heck. Just be sure you don’t have to change frequencies often – in the dark – in combat – in the rain – in the jungle. I’m guessing the Marines used the KISS method in comms planning whenever possible – during an active assault, stay on the same freq as long as safe/practical.

TBY Radio - N6CC

Above – A TBY radio with some old modifications. I bought this radio when I was about 16 years old from Algeradio in Hempstead NY for $15 I think, in 1965 dollars. A couple of weeks’ paper – route earnings. It did not have a power supply, battery box or antenna – just the basic RT. I had “Ham-mered it” by removing (GASP!) the microphone-headset connectors and replaced them with a single 6-pin connector for a PTT carbon handset. I did not have (or even know about) the accessories but I wanted to make it usable on 10 meters after I got my General Class ham license. I could easily talk with my buddy Eric across about a mile of suburban terrain using a modified CB ground plane antenna. He was using an HT-40, Lafayette HA-350 plus a 14AVQ vertical antenna.

This radio came with an SO-239 antenna connector on the port side – probably installed by the previous owner but that type connector was also a stock modification at some point. Since a 110 VAC supply was also available instead of batteries, they were probably also used as a ship-shore radio where an external antenna on the ship would be most effective in supporting the ashore Marines. Some examples have been seen in Navy haze – gray paint. (Reference 21).

TBY Radio - Frequency Tuning Chart N6CC

Above: The TBY has a unique frequency tuning chart serialized to each individual radio. This set was pretty drifty and did not have a direct frequency readout on the tuning dials. One for the transmitter, another for the receiver. The tuning chart provided the conversion from dial numbering to channel / frequency. This example still has its original chart.

TBY Radio Internal Configuration N6CC

Above: The TBY internal layout showing some the larger tubes and some of the Acorn “UHF” tubes, 8 tubes in all. Spare tubes were held in clips under the lid. The receiver and transmitter each had a 4-position rotary switch that inserted the necessary band coils into the circuit.

Since I didn’t have a power supply, I had lashed up a bunch of batteries to provide the required +150, +3, +1.5 and – 7.5 VDC to the 4 pin power connector on the bottom. With a built in crystal calibration oscillator, I could come close to the Amateur 28 MC band for comms plus I could also listen the local police and fire departments plus Channel 2 and 3 TV stations. I’m sure I never asked the local police cruiser “What’s your 10-20″…..

There is a fair amount of information on the Web about these radios in technical detail plus a few photos of them in use by the Marines and Navy. Primarily, they were used by the Marines at Guadalcanal, Bouganville, Tarawa, Iwo and other places; and notably by the Navajo Code Talkers who were organic with the Marine Divisions in those amphibious operations.

USMC Navaho Code Talkers with TBY Radio Official USMC Photograph

These Marine radio operators also used other USMC radios during their operations, especially the TBX. In simulated combat communications tests conducted early in 1942, General Clayton Vogel, Commander of Amphibious Forces Pacific evaluated the Navajo’s tactical communications potential. The Code Talkers were able to send and receive a 3-line English language message in 20 seconds. The same message, encrypted and then decrypted by the then-standard M-209 encryption device took 30 minutes. (Reference 22). Two hundred Navaho’s where initially recruited; the rest is history.

I wonder if the Code Talkers even received any CW training since their tactical advantage was their spoken language.  The use of CW would have been problematic with this radio – they key being physically mounted on a transmitter that is admittedly sensitive to vibration. More research is needed here….

My buddy Andy supplied the TBY radios and technical consultation to the movie “Windtalkers”. The entire premise of the movie was pure Hollywood nonsense and not much about, well, Code Talkers. But the radio gear and its operation was technically very accurate. Mr. Smith is a U.S. Marine Corps veteran Navaho Code Talker who was also recruited by the movie producer as a technical consultant. He provided Andy with a wealth of information on the use of the TBY radios in the WWII Pacific campaigns and this combined information was utilized in making the movie communications aspects more realistic. Photos by Andy Miller, KD6TKX

USMC Navaho Code Talker Albert Smith

Above: USMC Navaho Code Talker veteran Albert Smith with my buddy Andy on the set of the movie “Windtalkers”.

Code Talker Albert Smith autographing Andy's TBY on the Wind Talkers set

Above, Albert Smith autographs one of Andy’s TBY radios on the movie set in Hawaii. Wow.

In combat, tactical communications speed and security can be at odds with each other. These Marines provided both. In this case, the Navaho language as adapted for military operations. Thanks guys.

My TBY now resides as part of a permanent display at the Danville CA Veterans Memorial Building museum.