TR96 WWII Pilots Radio or Just Misheard?

[jamesinnewcastl]

Hi All

I've just been chatting to a man who was a Wireless Operator on Stirling Bombers in 1941! He mentioned that the Pilot used a Radio Telephone to talk to the tower when getting permission to land.

He said it was TR96 but I can't get any hits on Google. It wasn't TR1154/55 as he had those ones, and I can Google them.

Has anyone any information that could shed light on the TR96 please?


Cheer
James

[jamesinnewcastl]

Doh!

Isn't it funny how just asking a question makes you think differently.

TR1196 brings up loads of hits! I suspect he was just giving me the last letters.

Still interested in hearing any info on here though - would like to know the range.

Cheers
James

[techiesteve]

Could he have meant a TR1196? That was an aircraft transmitter.

Edit. You beat me to it. Full spec here http://www.rnmuseumradarandcommunica...org.uk/613.pdf

Range listed as 30 miles air to air, 50 miles air to ground.

[jamesinnewcastl]

Thanks Steve,

I've seen the control box on Spitfires too - Would the aerial for this thing be the one strung from the tail to the cockpit I wonder? I know that they also had 'trailing aerials' but the WO I was talking to said he would be busy winding this in as they were coming in to land.

Why only have transmit OR receive? I have head tales of aircraft being attacked as the pilot had left the R/T in transmit and was unable to get any warnings from the tower.

James

[Station X]

Why only have transmit OR receive?

With transmit and receive enabled at the same time the transmitter output would overload the receiver, jamming it or possibly damaging it. This applies even if the transmitter and receiver use different frequencies.

[M0FYA Andy]

Or perhaps it was a TR9 Transmitter-Receiver he was referring to?
The TR1196 replaced the TR9, but then it was ousted by the VHF sets TR1143 and TR5043 (the latter being the US SCR-522)
Andy

[jamesinnewcastl]

Don't think he meant TR9. Incidentally this site is quite amazing - the first bit is on the TR9

http://www.spitfirespares.com/Spitfi...ges/radio.html


Thanks all

James

[neon indicator]

It's extra-ordinarily difficult to to transmit and receive even at well separated frequencies at the same time. Over 110dB of isolation needed for a 5W to 10W transmitter.

Even today a 10m repeater might use TX and RX sites 5km to 10km apart with VOIP or UHF link between. A VHF repeater at 145MHz needs 4 x giant metal cylinders (or very complex helical filters, not really very easy below 300MHz) to give isolation. That's with modern filters and crystal or ceramic IF too.

A lot of modern apparently full duplex systems such as some mobile and Wifi actually use TDM half duplex (small time slots, and rapid switching between TX and RX) or large duplex split and very clever ceramic RF filters not available below 800MHz.

[Malcolm G6ANZ]

Hi, Duplexing is possible on the 2m band.Or at least it was! When i started I had a separate Tx and Rx. (Homebrew Tx and B40 with microwave modules converter) and I used to have two way conversations with a friend by transmitting at the bottom of the band and listening at the top. I used two aerials, a dipole for transmitting and a 14 element parabeam for receiving. separation was about 20 feet. This setup worked quite well with little or no desensitising on the receiver.

Malcolm

[jamesinnewcastl]

Thanks Guys

Just got a copy of AP1660 - a sort of Haynes Manual for the Stirling Bomber, and a surprise for me, there was a space for a TR9!

As far as Tx and Rx goes - I'm going to see if I can find out if the Tx position was biased so that it had to be held on transmit.

Cheers
James

[neon indicator]

Originally Posted by Malcolm G6ANZ

Hi, Duplexing is possible on the 2m band.Or at least it was! When i started I had a separate Tx and Rx.

It probably was desensing. I built a 435 MHz band repeater and I used handheld with 50 Ohm BNC termination instead of aerial to check desensing.

I had to insulate TX & RX from chassis, fit ferrites and do a couple of turns loop on every cable and have secondary screen over the TX and RX coaxes, earthed only one end (at the Duplex filters). 1.6MHz offset.

Then I could get 200m range with 100mW into a dummy load.

The repeater also had a VHF/UHF diplexer and a 2m rig set up as if a user on the 2m Repeater (20km away). Thus if UHF was receiving TX on 2M and 70cm and if VHF receiving, TX on 70cm only.

I have a 10GHz system that runs duplex by using separate side by side patch aerials, one H and other V. Using a dish with H & V feeds on one waveguide it's only really good half duplex, about 18dB port isolation. 10.25 GHZ RX, 10.56GHz TX.

I think in 1940s a ground station using separate aerial sites could have managed Duplex on same band, but an aircraft would have had to use quite different bands to operate Duplex.

The WWII TX and RX often separate on ground station with landlines to avoid de-sensing RX even on different bands. Even Aerials separated isn't enough if TX and RX in same room due to feeder loss and screening issues as alluded to on repeater.

Now you can have HF radio with 60MHz to 80MHz 1st IF and amazing filters to allow "close in" Working. I have had a TR16 military set and it's ability to receive with nearby transmitters is amazing. Some "Radios" today actually have a 1.2GHz 1st IF with 95dB+ dynamic range on 1st RF amp and mixer.

[GMB]

The TR9 was the pre-war and pretty obsolete transceiver used by pilots to talk to an airfield. It was replaced as rapidly as possible (but not quite fast enough for the Battle of Britain) by the TR1133 VHF set for land-based aircraft (and later by TR1143 and SCR522).

To avoid getting into trouble during the VHF roll-out the bulky TR9 became the standard shape for all future radio installations, so the TR1133 and the US made SCR522 all fitted in the same hole. It seems that there was concern that we could build aircraft faster than VHF radios.

The T1154/R1155 installation in big aircraft was not used by pilots, so they still carried the TR9 or TR9-shaped local airfield transceiver.

For some reason the Fleet Air Arm chose not to go VHF so the TR1196 was a modern replacement for the TR9 but using the same band. I think some big aircraft carried both a TR1196 and TR1133 so they could work with either. All this was additional to the T1154/R1155 for long range use.

[jamesinnewcastl]

It seems that the TR9F was fitted to MkIII and MKIV Stirlings.

[M0FYA Andy]

So is the general feeling now that he meant TR9 or TR1196?

Andy

[jamesinnewcastl]

Hi

I suspect that he would have used both in his time and a good many others! I'll ask him when I have a few more questions lined up.


James