# Siemens T5 Emergency Transmitter



## Shipbuilder (Jun 30, 2005)

This may arouse old memories of ex Siemen’s R/Os. I came across it quite by accident yesterday. It is the circuit diagram of the Siemens T5 emergency transmitter. It is hard to believe how simple equipment was 50 years or so ago. We were expected to learn these circuits by heart and be able to draw them for exam purposes as well as knowing how they worked. Even after all this time, it is still ingrained in my memory. Just a simple L/C oscillator coupled into a power amplifier. When the key is pressed, Rla1 relay contact shorts out R10, removing the large negative bias from both valves, allowing them to conduct, whilst Rla2 flips the aerial from the receiver to the transmitter. Modulation was achieved by feeding 110V at 700 c/s into T2, the secondary of which is in the anode circuit of V2. The tuning of the pi-network was achieved with a string-and-pulley device that dragged a large dust-iron core through the middle of L5.

Power came from the 24 volt emergency battery feeding a motor-generator with an output of 800 volts DC for the HT, 110 volts at 700 c/s for the modulation and the much lower LT supply to both valves.

I suppose such equipment would be sneered at today, but it was strong and reliable and most R/Os could repair any fault that occurred in it with very little trouble. I sailed with four of these T5s over several years and none of them gave any trouble at all.

Bob


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## radioman1969 (Dec 12, 2010)

*T5*



Shipbuilder said:


> This may arouse old memories of ex Siemen’s R/Os. I came across it quite by accident yesterday. It is the circuit diagram of the Siemens T5 emergency transmitter. It is hard to believe how simple equipment was 50 years or so ago. We were expected to learn these circuits by heart and be able to draw them for exam purposes as well as knowing how they worked. Even after all this time, it is still ingrained in my memory. Just a simple L/C oscillator coupled into a power amplifier. When the key is pressed, Rla1 relay contact shorts out R10, removing the large negative bias from both valves, allowing them to conduct, whilst Rla2 flips the aerial from the receiver to the transmitter. Modulation was achieved by feeding 110V at 700 c/s into T2, the secondary of which is in the anode circuit of V2. The tuning of the pi-network was achieved with a string-and-pulley device that dragged a large dust-iron core through the middle of L5.
> 
> Power came from the 24 volt emergency battery feeding a motor-generator with an output of 800 volts DC for the HT, 110 volts at 700 c/s for the modulation and the much lower LT supply to both valves.
> 
> ...


Hi Bob, I did my PMG on this TX in 1968. I saw it fitted to an old Clan Line boat once during a ship visit to Belfast docks. 

Other AEI gear in our college was T10 main tx, G11/G12 Rx's and the Q29 Auto Alarm - the selector function was a joy to learn - about a hundred relays ! Never had the joy to sail with AEI gear only GTZM and IMR gear (1500W - ST1400, great tx).

Best regards
Ken


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## Shipbuilder (Jun 30, 2005)

Hi Ken,
I wonder if you were at Wray Castle? as far as I knew, they were the only ones training on Siemens gear. I was there 1959 - 61 and again in 1962. I sailed with all the AEI gear you mention and also the older SB218A auto alarm that was full of relays. We had to learn the relay circuit of that as well. Sailed with SB218a in FREDERICK T. EVERARD. Oldest Siemen's Txs I sailed with were the MF SB502 and SB186X HF. All good reliable gear, but not very powerful.
Bob


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## radioman1969 (Dec 12, 2010)

*T5*



Shipbuilder said:


> Hi Ken,
> I wonder if you were at Wray Castle? as far as I knew, they were the only ones training on Siemens gear. I was there 1959 - 61 and again in 1962. I sailed with all the AEI gear you mention and also the older SB218A auto alarm that was full of relays. We had to learn the relay circuit of that as well. Sailed with SB218a in FREDERICK T. EVERARD. Oldest Siemen's Txs I sailed with were the MF SB502 and SB186X HF. All good reliable gear, but not very powerful.
> Bob


Hi Bob. No sorry I wasn't at Wray Castle. It was Belfast Radio School which was located at Hardcastle Street. I think the radio equipment came off the passenger ship 'Ocean Monarch/GJXD' as that was the way it was set up there. They also had a AEI D/F which was single loop type (can't remember the number of it though). Radar was Kelvin Hughes KH14/9 which sailed several times on Joe Shell boats (and regularly went on the blink - altho not as bad as Marconi's Hermes/Argus radars - nightmares those two.

The guy I relieved on one shell boat handed me the 'screwdriver' which I duly passed on to the next guy who relieved me !


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## Ron Stringer (Mar 15, 2005)

At Brook's Bar we had to learn the Marconi Reliance transmitter circuit diagram. For those that do not know, the Reliance used the MF section of the Oceanspan transmitter, so was somewhat more complicated than the Siemens T5 as shown, with 807 modulator and RF output valves and all.


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## Shipbuilder (Jun 30, 2005)

The Siemen's DF was the R19 and I found it was very good. Although at the time, I looked with envy on those with automatic Marconi DFs, but when I eventually sailed with them, I never really liked the "quavering" pointer.
Siemen's gear was very good for training on because of the extensive monitoring system where the anode currents and principle voltages could be checked at the flick of a switch without even opening it up. Also liked having the fuses on the front panel rather than hidden away inside.
Bob


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## Shipbuilder (Jun 30, 2005)

Here is the Oceanspan VI circuit.
Bob


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## Ron Stringer (Mar 15, 2005)

Shipbuilder said:


> Here is the Oceanspan VI circuit.
> Bob


Very similar to the Reliance but with an LC oscillator instead of crystals (more like the 'Span I) and less the MF/HF switching.


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## Shipbuilder (Jun 30, 2005)

I never really like the horrible looking EF50. I accept that the performance of the valve itself was pretty good. I have also heard it described as "the valve that won WWII! But that dreadfull aluminium can made it look more like a tin of beans! But the thing I disliked most about it was those ridiculous little pins, prone to corrosion and expensive valveholders that are so difficult to find these days. What a difference from the pretty little EF39s, ECH35s and EBC33s with their red coatings and shapely envelopes!
Bob


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## mikeg (Aug 24, 2006)

The EF50 looked more like an electrolytic capacitor can than it did a valve.

Valves at christmas look really great with their filaments aglow, anodes glowing red and a soft blue glow playing Noddy Holder at 11 (K)

('Australian' valves plus comments about soft..please)


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## Shipbuilder (Jun 30, 2005)

Here is a mint condition EF50 that I use frequently. A very good pentode, but not very attractive. Seveal years ago, got a box full on car boot for next to nothing. Must admit, I have removed several from their cans and put them in International Octal bases where, although they perform just the same, they look a lot better.
Bob


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## Graham P Powell (Jun 2, 2007)

I sailed mainly on ships with AEI gear. Royal Mail and Houlders. Very simple, very robust and which gave little trouble. The Q29 ( I think that was it) auto alarm could be problematic with all those flippin relays. I sailed with a 250w Telefunken HF tx where the keying relay gave trouble . On RML we had separate HF and MF receivers but with Houlders the ship had two mounted one above the other with a common power supply. Changing from MF to HF could be a slow process.
We had two large (600W) transmitters on RML ships. One MF one HF. On one trip, the HF one packed up. The Chief and 2nd found out it was the main transformer open circuit. They took HT from the other power supply using some wire taped to the deckhead and proceeded to dismantle said transformer.
They unwound it, counting the turns until they found the break , fixed it and restored it to service. They were old fashioned R/O's!.
At GKA we had racks of amplifiers covering the marine HF bands and they consisted of banks of EF50's. I should have saved a few before they went into the skip.
rgds
Graham Powell


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## hawkey01 (Mar 15, 2006)

Graham,

So true. I have often wondered what happened to so much of the old equipment. Including the really old stuff we had in our mini museum. Of course I had left before the final demise so not around to rummage, mores the pity. I had been promised various photos of ships and some of the Aero stuff but nothing came my way. 

Neville


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## david.hopcroft (Jun 29, 2005)

The MF & HF receiver was the G12. The changeover switch was just out of sitting position reach. Does anyone remember the Siemens SB186X HF Tx, with the pull out tuning coil slug ? On one ship, it was next to the G12, and when on 16mhz it was fully pulled out. If you went to change the G12 back to MF, and stood up without thinking......... crash ..............a nasty crack on the head !!

David
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## Shipbuilder (Jun 30, 2005)

David,
I sailed with the SB186X in the FREDERICK T. EVERARD and remember the big brass rod sticking out of the front.

Also the T10 with IF R/T had the send receive switch on the front panel of the Tx rather than the handset and one had to lean over to work it. On another ship, Captain could never quite get the hang of it, and didn't like duplex calls, so I had to sit there trying to anticpate when he was going to speak or listen and work the switch for him. His dislike of duplex calls came from the first phone call I put through for him to head office. After speaking to the first person, he asked them to put him though to another department and then, turning to me said "Spend some more of their $?#@+** money, eh, sparks?" and of course they heard him! It was simplex from then on!

Bob


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## Graham P Powell (Jun 2, 2007)

Neville, My understanding was that Phil Lewis had it but not sure whether or not that is true and poor old Phil is no longer with us. I have a big TX valve and very large tuning condenser ex Portishead. Plus of course one of the keys ( given to me by one of the engineers). I also have a couple of pictures including one nobody wanted only me. An aerial view of Southampton docks during the seamans strike when I was on one of the few British passenger ships to sail in and sail out again. I would have liked the bit of Richard Branson's baloon and the picture of the Queen!.
rgds
Graham


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## John David Mair (Nov 3, 2010)

Wray Castle, all of us who went there will remember the Siemens T10, receivers and the Auto alarm etc.
Standard PMG question: Draw the circuit diagram of an autolarm and explain the action.


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## david.hopcroft (Jun 29, 2005)

At the start of GPS when it was still FGMDSS, I visited OST with Ron Champion who was with SES at Greenhithe at that time and was developing the system. On the way over, we were talking about Siemens gear and the time he was with them. He said of the T10 - 'now there's a transmitter that was properly engineered, not just put together'. I quite agree. Never gave me any problems.

David
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## Graham P Powell (Jun 2, 2007)

David, What was a T10?. I can remember the T5 but after that it all gets a bit hazy. The HF /MF tx's we had with RML were in cabinets that had the corners rounded off. The turning was easy, select band and frequency, hold down key and turn knob for maximum reading. Full power, I think they were around 600W which was more than Marconi tx's of similar vintage I think.rgds
Graham Powell


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## david.hopcroft (Jun 29, 2005)

Hello Graham

It was badged AEI, and properly called a T10A, MF WT/RT only and I think 100w was nearer the mark, with RT belting out all of 60w. Never failed me though each time I came across one. 

The thumbnail is on the Aulica/GFHC, but was the same layout as Partula/GBYH that I was on for a time.

David
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## Graham P Powell (Jun 2, 2007)

Hi David, The Swan River ( Houlders) had one of those. Very reliable. That ship also had 250W H/F W/T tx labelled as Telefunken. It worked okay but I had trouble with the keying relay. I unfortunately took over from an R/O who had been on the ship for ten years. Consequently I didn't have his knowledge of the gear and never seemed to able to satisfy the old man. I did like AEI gear though.
Very well made . Very robust and for the most part reliable.
rgds
Graham Powell


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## david.hopcroft (Jun 29, 2005)

Graham

That would be the T36 - shown alongside the T10A. Also same on Partula. That one though, had a larger EHT transformer mounted outside the casing - suitably insulated from wandering hands !! - because the original design was not sufficient and so tended to blow up. 

Any experience of the BTH RMS2 radar ? When I joined, there were about a dozen deck lights connected in a series/parallel arrangement sticking out of the cabinet. My predecessor had very cleverly wired them up to replace one of those big green wire wound heat dissipating low wattage resistors in the power unit !

David
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## Graham P Powell (Jun 2, 2007)

Hi David, Thats the Telefunken transmitter I had. The radar was a BTH.
The transceiver was in the alleyway leading to the chartroom. The 2/O slipped on a oily patch and it was a delay line in the radar leaking oil. It hardly ever worked for the rest of the trip. When I did eventually get it repaired, I found a pile of duff delay lines in the motor generator room. I managed to keep everything going but it was a bit of nightmare for the first trip on my own. For some reason, after I left it, Marconi's put two R/O's on the ship which had a radio room like a broomcupboard. The radio surveyor told me it was one of the smallest he had ever seen. Certainly you could operate everything from a sitting position. rgds
Graham Powell


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## Larry Bennett (Aug 28, 2005)

hawkey01 said:


> Graham,
> 
> So true. I have often wondered what happened to so much of the old equipment. Including the really old stuff we had in our mini museum. Of course I had left before the final demise so not around to rummage, mores the pity. I had been promised various photos of ships and some of the Aero stuff but nothing came my way.
> 
> Neville


Neville

As far as I am aware, the vast majority of the items in the mini-museum were taken to BT Archives in London for further scrutiny. From there I don't know what happened, but I was working with them for a few months after the station closed and we loaded up a large BT van with files of written archives, photographs and other material.

The photos and pictures were distributed to 'selected' staff (I was not involved as I was working for BT's Satellite Services and didn't get anything either). Suspect some excellent pictures lining the walls of certain houses in the Burnham on Sea area!

Larry +


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## Graham P Powell (Jun 2, 2007)

We had an R/O off the Queens at GKA. He told me that the MF tx was tuned to an especially low note so that they could be heard above the normal din on 500khz. Whether that was right or not I have no idea!. I believe both ships were equipped with coast station transmitters.
rgds
Graham Powell


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## david.hopcroft (Jun 29, 2005)

Digressing a little, and getting back to the SB186x - does anyone have a photograph of one, or know where one might be please ?

I remember on GWWJ trying to raise GKA from only just off the N.African coast near Safi, but with no success. It was Christmas Eve though so maybe my 'voice' wasn't loud enough !

David
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## david.hopcroft (Jun 29, 2005)

No doubt GM4BES - if he sees this - will immediately say I should have waited till after the single op periods, and called GPK on 500 !!

But I was a mere lad at that time who did not appreciate the nuances of propagation.

David
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