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Forum Home > General Discussions > The T1509A - Looking for information

Sean Williams
Member
Posts: 4

Hello All.

I stumbled across this wonderful site while looking for information about the T1509 transmitter.

I have a half share of one - and have some questions about  the transmiter, its accessories and associated equipment, there have been references made to parts of the system that do not appear in any AP that I have for it.

On the historic side of the transmitter, I would also like to find out more regarding the use, maintenance, and peculiarities that were noted during their service at RAF Greatworth, a station that until recently I knew nothing of.

My first question relates to the antenna arrays, and more specifically, if there was any use of an natenna matching unit, I would have expected resonant antennas to have been used, so the need for a tuner would have been negated, however, having been offered "the correct tuner for the 1509" over the weekend, I am slightly intrigued!

Anyway, I hope that there is a chance someone will remember the 1509 in service and be able to help.


Many thanks

Sean Williams

October 10, 2011 at 3:43 AM Flag Quote & Reply

M Hall
Site Owner
Posts: 76

As the caged rhombics were aranged for specifice direction/frequency bands, the tx's aerial coupling circuits were tuned into the aerial in use for that band, no other matching units were used while I were there. Aerials were interconectible with all tx's with jumpers, all were on 600ohm ballanced feeders. Good ole days them.

--

Martin. (aka Tom)

 

October 10, 2011 at 3:59 AM Flag Quote & Reply

Sean Williams
Member
Posts: 4

Thanks, Martin, Much as I expected really - simplicity of operation would have been paramount I guess - another set of tuned circuits between the TX and the antenna would have been a source of trouble.


The plot thickens!

October 10, 2011 at 9:15 AM Flag Quote & Reply

Sean Williams
Member
Posts: 4

This is a copy of some information I posted on the UK vintage Radio Discussion Forum - all results of my research today - hope it is of interest to some of you.


Well, fresh back from the National Archive.....

 

For once, it seems we can beleive something the RSGB printed....

 

The T1509 was designed in collaboration with the RAE, Farnborough, and "The Gramophone Company" (aka EMI) - this is proven by documentation that includes the initial devopment contract, and order for three units initially, then increased to ten.

 

Prototype costs were contentious - EMI had initially been granted £9000 to develop and deliver the 10 units for approval, this was approved by the Ministy of Supply, in that figure was a projected contingency of 100%, despite this generous contract EMI submitted a request via RAE Farnborough for the contract terms to be increased to £12,500 - there are several quite blunt and to the point letters sent from lofty places regarding this request..... this all occured towards the end of 1943, and into 1944.

 

Moving on slightly it appears that EMI were to submit the 10 hand built units for approval towards the end of Oct '45, sadly the archive is a little thin in this area, and more research needs to be done.

 

Around the end of 1945 a meeting was held at Hayes (the home of EMI) where several transmitter projects were discussed - the T1509 hit No.3 on the agenda, and the following orders were discussed, EMI were to produce 400 units, and A.C. Cossor were to produce 600 units to EMI's prototypes.

 

There had been a period of co-operation between these two companies for some time, no doubt due to the ongoing "War Effort" - as yet I have not found the contract for supply of these, but think this was made factual soon after the meeting took place.

 

The contract for design of the "Control Unit 310" was passed to A.C.Cossor, and it appears they were exceptionally quick off the mark witrh these - it was a matter of about 6 weeks between prototype request, and production model!

 

Onto Antenna Coupling Units.....

 

There was a request from the Antenna Rigging section of the RAF (with some paperwork from Henlow if you are reading Alf....) for some kind of matching unit.

 

EMI suggested that no single unit would be capable of matching from 1.5-20Mhz, while giving the impedance transformation from 43r to 600r that the design breif called for, so they proposed to use a selection of four different units, each covering a different band. RAE Farnborough pointed out that this would be a most uneconomical method - the T1509 was envisaged as a mobile station, and as such would need all four units to be shipped to allow the full range of frequencies to be catered for.

 

This discussion started in 1946, and was still ongoing in 1949 - at this time trials were conducted of two differnt tuners - one rated at 4KW power handling, the other more suited to the output of the T1509. The specification called for an integral "Artificial Antenna" - the 4KW unit could not manage that due to weight considerations, and it is unclear if the other tuner managed to squeeze one in.

 

To date, there is no mention of Marconi, or STC, so I think we can probably discount these two manufacturers......

 

So, a breifish resume of my findings today, as is usual with research, there are many more questions left unanswered, and many more added!, in all there is around 1200 pieces of information spread across 3 files I have seen today, with a further three to look at, from there on who knows - I have a lot of other places to go looking now!

 

To end with a question.....

 

What happened to A.C.Cossor's Archive, as well as the archive from EMI?

 

Cheers

Sean

 


October 14, 2011 at 4:47 PM Flag Quote & Reply

M Hall
Site Owner
Posts: 76

So looking at this from a different perspective, the four T 1509's we had in the early sixties, would have been installed at RAF Greatworth in the mid/later fifties? I don't think they were there in the nissen TX Hall (judging from the photos!). Nice work Sean and interesting too, I'd guessed that the T1509 was a lot younger than the SWB's, now it's no guess. The SWB's 8's and 11's go back to the early/mid thirties, today their build quallity would be thought legendary, as they were made to last forever, and they would have too but the progress of technology and changing requirements made them obsolete, along with the T1509's.

--

Martin. (aka Tom)

 

October 16, 2011 at 8:28 AM Flag Quote & Reply

Eric Rogers
Member
Posts: 13

During my time at RAF Greatworth in 1958/59, the T1509`s were used on "short haul" circuits to Second Tactical Air Force Germany (2nd TAF), they were CW transmitters of about 500watts, using machine morse (100wpm), the T1509`s fed vertical aerials hung from a "Triatic", a sort of triangular catenary between 90foot masts in the field just in front of the Hall entrance, (members may remember where the Ensign flew from, these aerials were just beyond there). The T1509`s did not have any matching units, and as far as I can remember used co-axial cable to supply the aerials, which were probably 1/4 wave or 3/4 wavelength fed against ground, this neatly does away with the need for matching units. They were seldom if ever QSY`ed, they operated on "set" frequencies, so the vageries of propagation probably did not affect them too much on the 500/600mile circuits employed.

October 19, 2011 at 8:55 AM Flag Quote & Reply

Sean Williams
Member
Posts: 4

Nice to hear about their use, and the sort of circuits they were set for - Ive been away a while - the curse of jobhunting!, this has somewhat scuppered the research!


Anyway some interesting info, and it does seem that matching units may have only been used for "mobile" installations, something that must have been a sight to behold!


Please keep the stories coming - there is so little information about Ground Comms to read up on - probably less glamorous than RADAR, although I think it is much easier to understand.


Cheers

Sean

October 23, 2011 at 5:32 PM Flag Quote & Reply

Dave Lloyd
Member
Posts: 2

We ran some 1509’s at Isthmus transmitters in Aden in the early 60’s. There were 4 just inside the front door and a further 20 or so in a back “corridor” at the rear of the site, the only air conditioned part of the site.

I don’t recall any AE matching units but I remember that at least two of them had Navy markings on them. As they were mounted on rubber shock-proof feet within a metal frame that could be bolted down, I suppose that they would be suitable for mobile or ship-born use. Perhaps a tuning unit would have been required “on board”.

Most of the sets were for CW use but some were used for voice. I remember walking past some and hearing them muttering away, possibly due to loose transformer laminations in the modulation section, a very eerie sound in the middle of the night when your on the way to the loo!

Dave

January 28, 2012 at 10:45 AM Flag Quote & Reply

Dave Lloyd
Member
Posts: 2

Just a further thought on the matching units used on the T1509 Tx's.  The Output from the the Tx was coaxial and in the fifties, sixties and early seventies, most feeder systems to the Ae,s on the Ae farms were 600 ohm openwire feeders.  I remember matching units, "Balun"s  (Balanced/Unbalanced) units being mounted near the Ae's for matching the dedicated 1509 use to convert the coax feed to Ae's such as cage dipoles that were fed from the 600 ohm outputs.

This might be a simplistic answer but I remember this configuration on quite a few Ae farms. 

February 10, 2012 at 6:50 PM Flag Quote & Reply

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