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Old 14th Mar 2023, 1:03 pm   #1
iainmaoileoin
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Default Russian 1940s-1950s tank radio 10rt-26

I have the rx and tx units of a 10rt-26 (~3-6meg) Russian tank radio system. Internally it looks in fair condition.

I dont have the 2 generator/motors that run off the 24/26volt batteries and generate the ?200v and ?400volt HT, nor do I have the pin outs for the front panel.

I would like to renovate the beast for display in the radio section of my WW2 bunker - www.behind-the-radar.co.uk - I dont need the motors/genny, I would be prepared to use a couple of HV supplies and a 26v to drive the heaters.

The unit appears to use part of the circuitry in the receiver when in transmit mode - I guiess it means the rx and tx frequency are locked..... I dont know what else is novel in here.

I have put up the best schematics I can find of the power-unit on the web-site. But I just cant figure out how it works and what the various pins are for. (The "dots" showing joined wires may be missing and while I think I may have a good guess, I cant apply power on that basis!). Some of the symbols for relay/solenoid are strange to me. What I think I can see is that the 400v genny does not power up until the TX unit is present...

Can anyone help interpret the schematic for the PSU? (I have been around many Polish/Estonian/German/Russian web-sites but just cant find anybody/any schematic that is clear and obvious).


I have put a German schematic of rx/tx/power up on http://www.behind-the-radar.co.uk/10rt/10rt-26psu.jpg and the full schematic on http://www.behind-the-radar.co.uk/10rt/10rt-26.jpg.

Some old 360 degree photos of the radio display is at http://www.behind-the-radar.co.uk/10rt/radioroom.jpg Zoom in on it then scroll about to see some of the radios.

All help appreciated and will be acknowledged on the display.
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Old 15th Mar 2023, 10:50 am   #2
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Default Re: Russian 1940s-1950s tank radio 10rt-26

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Old 16th Mar 2023, 6:15 pm   #3
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Default Re: Russian 1940s-1950s tank radio 10rt-26

Quote:
Originally Posted by iainmaoileoin View Post
jpgs copied up for long-term-visibility
AFAIK, the originals were US made.
They were selling them cheap on the surplus market. It was part of the lend-lease program. Isn't it wonderful, the way they paid us back!
Dave, USradcoll1
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Old 16th Mar 2023, 7:00 pm   #4
iainmaoileoin
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Default Re: Russian 1940s-1950s tank radio 10rt-26

Quote:

AFAIK, the originals were US made.
They were well made the innards are well assembled, all the markings inside my unit are in cryllic. So the Americans must have been busy.

Does that mean I can find schematics in the states? I have been hunting to my east.
Quote:
They were selling them cheap on the surplus market. It was part of the lend-lease program. Isn't it wonderful, the way they paid us back!
Dave, USradcoll1
I will keep out of the politics ;-)
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Old 16th Mar 2023, 7:34 pm   #5
trh01uk
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Default Re: Russian 1940s-1950s tank radio 10rt-26

Iain,

here's a few pointers on the power unit.

Terminals K3-1 and K3-2 connect to the 24V supply. +ve and -ve respectively.

B3-7 looks to be the "start contacts" which start up the two dynamotors. That's presumably a relay contact, but I am not clear where the relay coil to actuate it is located.

The 400V HT rail goes out on Sch3-1 at pin 4.

P3-1 looks to be a relay coil. Its right hand pair of contacts switch the 24V DC supply to the 400V dynamotor. So P3-1 is most likely a SEND relay.

The 200V supply is unclear because it looks like some "joining dots" are missing on the diagram. I would say the junction of C3-2 and Dr3-2 is the point where the fully smoothed 200V supply is located. Where it goes from there is unclear. If I am right, then the 200V supply is routed to:
  • Sch3-2 pin 3
    P3-1 pole of the left hand contact set

Where the 200V is routed after that is going to take some more concentrated study of the whole diagram. I offer the above for a start - have to go out right now, so must leave it there for now!

Richard
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Old 17th Mar 2023, 12:09 am   #6
iainmaoileoin
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Default Re: Russian 1940s-1950s tank radio 10rt-26

Thanks for taking the time to look at this. It all helps.
Quote:
Originally Posted by trh01uk View Post
Iain,

here's a few pointers on the power unit.

Terminals K3-1 and K3-2 connect to the 24V supply. +ve and -ve respectively.

B3-7 looks to be the "start contacts" which start up the two dynamotors. That's presumably a relay contact, but I am not clear where the relay coil to actuate it is located.
I am guessing that B3-7 could just be the on/off?.
BUT I THINK that the P3-1 (is that a symbol for a coil/relay) closes off the circuit to the 400 volt motor, so only the 200V starts right away?
If that is the case then something driving pin5 of SCH3-1 closes the relay and energises the 400 V motor? I wonder if something on the Throatmicrophone (Kehlkopfmikrofon) connects to ground and runs up power? Perhaps when the mic is plugged in the TX powers up?

Quote:
The 400V HT rail goes out on Sch3-1 at pin 4.
ta
Quote:
P3-1 looks to be a relay coil. Its right hand pair of contacts switch the 24V DC supply to the 400V dynamotor. So P3-1 is most likely a SEND relay.

The 200V supply is unclear because it looks like some "joining dots" are missing on the diagram.
Aye, that is what is scr*wing me up
Quote:
I would say the junction of C3-2 and Dr3-2 is the point where the fully smoothed 200V supply is located.
Thanks, I was not looking at that point - I was working on the point after the S13-2 fuse and the Dr3-2 choke.
Quote:
Where it goes from there is unclear. If I am right, then the 200V supply is routed to:
  • Sch3-2 pin 3
    P3-1 pole of the left hand contact set

Where the 200V is routed after that is going to take some more concentrated study of the whole diagram. I offer the above for a start - have to go out right now, so must leave it there for now!

Richard
I will keep reading and drawing. I am wondering what the TF "four pin" connector on the receiver circuit is for - I was 1/2 thinking high-voltage supply, but no.

All the other dots are so damn clear that the missing ones on the power supply are very strange!

Thanks for your input. Appreciated.
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Old 17th Mar 2023, 10:10 am   #7
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Default Re: Russian 1940s-1950s tank radio 10rt-26

Quote:
Originally Posted by iainmaoileoin View Post
I am guessing that B3-7 could just be the on/off?.
BUT I THINK that the P3-1 (is that a symbol for a coil/relay) closes off the circuit to the 400 volt motor, so only the 200V starts right away?
If that is the case then something driving pin5 of SCH3-1 closes the relay and energises the 400 V motor? I wonder if something on the Throatmicrophone (Kehlkopfmikrofon) connects to ground and runs up power? Perhaps when the mic is plugged in the TX powers up?

Yes, you are right that B3-7 is a simple on/off switch! Nothing complicated there!

The 200V dynamotor starts as soon as the unit is switched on, because HT is needed to get the receiver to work.

The 400V dynamotor will be energised whenever the unit is put into "transmit" mode. Normally that will be by a pressel switch on the microphone. Do you have the correct microphone for this unit?


Richard
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Old 17th Mar 2023, 10:17 am   #8
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Default Re: Russian 1940s-1950s tank radio 10rt-26

Here are details of the transmit/receive switching system.

There is a relay top left of the large diagram, marked "125" I think. That is the aerial changeover relay. One side of its coil goes to the 24V rail, which comes in via pin 7 of connector "138".

The other side of the coil goes to the middle pin of the connector marked "Kehlkopfmikrofon". That will go to the pressel switch on the microphone. Incidentally the microphone is a carbon type, since there is DC voltage applied to energise it. This line also picks up P3-1 in the power unit to start up the 400V dynamotor.


Richard
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Old 17th Mar 2023, 11:21 am   #9
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Default Re: Russian 1940s-1950s tank radio 10rt-26

I think the mystery of the 200V HT rail is solved if a missing connection is made between the junction of C3-2 and Dr3-2 and the single line that crosses that junction.

Once that correction is made, it appears to relay P3-1 switches the 200V between the receive system, and the low power circuits of the transmitter. Specifically it feeds 200V to the anodes of valves, 203, 204, 205, 206, 207 in receive mode.

I think there is another missing connection on the 200V Send circuit,which comes out of the P3-1 normally open contact. Most likely it should connect to Sch3-1 pin 3 and Sch3-2 pin 2.

I recommend you do some circuit tracing and establish that my analysis is correct.

Richard

Last edited by trh01uk; 17th Mar 2023 at 11:32 am.
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Old 17th Mar 2023, 4:41 pm   #10
usradcoll1
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Default Re: Russian 1940s-1950s tank radio 10rt-26

Quote:
Originally Posted by iainmaoileoin View Post
Quote:

AFAIK, the originals were US made.
They were well made the innards are well assembled, all the markings inside my unit are in cryllic. So the Americans must have been busy.

Does that mean I can find schematics in the states? I have been hunting to my east.
Quote:
They were selling them cheap on the surplus market. It was part of the lend-lease program. Isn't it wonderful, the way they paid us back!
Dave, USradcoll1
I will keep out of the politics ;-)
A bad habit of mine.
I have one of those sets! I'll probably pluck the valves and trash-can the rest.
IIRC, Philco made the set!
Dave, USradcoll1.
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Old 20th Mar 2023, 4:18 pm   #11
iainmaoileoin
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Default Re: Russian 1940s-1950s tank radio 10rt-26

Quote:
Originally Posted by trh01uk View Post
Here are details of the transmit/receive switching system.

There is a relay top left of the large diagram, marked "125" I think. That is the aerial changeover relay. One side of its coil goes to the 24V rail, which comes in via pin 7 of connector "138".

The other side of the coil goes to the middle pin of the connector marked "Kehlkopfmikrofon". That will go to the pressel switch on the microphone. Incidentally the microphone is a carbon type, since there is DC voltage applied to energise it. This line also picks up P3-1 in the power unit to start up the 400V dynamotor.


Richard
No I dont have a mic for this radio yet. But I hear your comments about spinning up the 400 volt etc. I am beginning to follow.
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Old 20th Mar 2023, 4:21 pm   #12
iainmaoileoin
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Default Re: Russian 1940s-1950s tank radio 10rt-26

Quote:
Originally Posted by trh01uk View Post
I think the mystery of the 200V HT rail is solved if a missing connection is made between the junction of C3-2 and Dr3-2 and the single line that crosses that junction.

Once that correction is made, it appears to relay P3-1 switches the 200V between the receive system, and the low power circuits of the transmitter. Specifically it feeds 200V to the anodes of valves, 203, 204, 205, 206, 207 in receive mode.

I think there is another missing connection on the 200V Send circuit,which comes out of the P3-1 normally open contact. Most likely it should connect to Sch3-1 pin 3 and Sch3-2 pin 2.

I recommend you do some circuit tracing and establish that my analysis is correct.

Richard
Yep! You are a magician. I just could not get my head around what was going on here - I could see the "missing" dots could only be in 1 of 2 places but kept getting list in the bigger diagram.

I can trace from here.
Thank you.
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