The rig was used to test large alternator and motor rotors impedance and for interstrand and interturn insulation resistance checks through the 60s
Possibly used with a step up tranf, since the highest tap selection is 300Volts
But then we also use, still use, a pair of 1000hz MG sets for that....similar age. Built to last though
Possibly used with a step up tranf, since the highest tap selection is 300Volts
But then we also use, still use, a pair of 1000hz MG sets for that....similar age. Built to last though
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Some pictures 
So heres a few photos
Firstly, the close-up again, with the name corrected......
Then the small collection of the output valves. Condition unknown........yet.
Then the rectifier bank, which is in the lower portion of the cabinet behind the louvres (follows in the next photo):
And the cabinet,(trying to get it all in here. It must be close to 6'6", im 6'3" and its bigger than me
The Output tubes/valves hide behind the middle louvred portion, in a pair, seperated by a vertical quad (I think) which are the drivers. I assume .
I should get a photo of that really, its quite a neat arrangement.
So heres a few photos
Firstly, the close-up again, with the name corrected......
Then the small collection of the output valves. Condition unknown........yet.
Then the rectifier bank, which is in the lower portion of the cabinet behind the louvres (follows in the next photo):
And the cabinet,(trying to get it all in here. It must be close to 6'6", im 6'3" and its bigger than me
The Output tubes/valves hide behind the middle louvred portion, in a pair, seperated by a vertical quad (I think) which are the drivers. I assume
.I should get a photo of that really, its quite a neat arrangement.
Wow, looks very similar to some shaker amps I saw in my apprenticeship.
After that I worked for an induction heating company for a while. They still used 50 and 100KW Delapina tube induction heating machines. The rectifiers were originally high vacuum types but were converted to SS diodes in six long strings with appropriate balancing R and C across each one. The HT was "only" 6KV so they were simply mounted on paxolin panels in air. A fan blew on them not only to help cooling but also to stop dust build up due to the HV. Your amp/s could quite easily be converted to SS rectifiers.
The tubes do look like STC 4212 you can get them but they aint cheap.
Cheers
Matt.
After that I worked for an induction heating company for a while. They still used 50 and 100KW Delapina tube induction heating machines. The rectifiers were originally high vacuum types but were converted to SS diodes in six long strings with appropriate balancing R and C across each one. The HT was "only" 6KV so they were simply mounted on paxolin panels in air. A fan blew on them not only to help cooling but also to stop dust build up due to the HV. Your amp/s could quite easily be converted to SS rectifiers.
The tubes do look like STC 4212 you can get them but they aint cheap.
Cheers
Matt.
I've been meaning to reply to this thread but haven't had the chance tell now. Those mercury vapor rectifiers are pretty small. I bet there similar to an 866a tube.
That unit looks different then expected. I thought it would be closer to a radio transmitter. I am guessing the unit doesn't go that high in the frequency range. I bet it would make a killer sub amp.
That unit looks different then expected. I thought it would be closer to a radio transmitter. I am guessing the unit doesn't go that high in the frequency range. I bet it would make a killer sub amp.
I would imagine a limited frequency response even though from data another member posted in this thread, the upper BW limit of the valve is 1.5 Mc/s.
Which could explain why the schematic claims 250/500/1kW, despite looking like a single pair running push-pull. From the datasheet 600 W is quoted, so Id imagine the BW is limited to gain more power from them.
Since it was used (from what I understand) to impedance test large generator/alternator/motor rotors, and for insulation checks, it could have been used with an external oscillator, or it could itself oscillate...I haven't looked into the wad of info I have, too much work to do whilst im in the office
Which could explain why the schematic claims 250/500/1kW, despite looking like a single pair running push-pull. From the datasheet 600 W is quoted, so Id imagine the BW is limited to gain more power from them.
Since it was used (from what I understand) to impedance test large generator/alternator/motor rotors, and for insulation checks, it could have been used with an external oscillator, or it could itself oscillate...I haven't looked into the wad of info I have, too much work to do whilst im in the office
1.5 Mc,wow that's surprising. I'm betting your right. What is the input requirements and output impedance?
That thing has to be fun to just look at. I love to just study things like that. The way they built things back in the 30's to the end of tube only designs.
Do you know the a.c. Input voltage to those mercury vapor rectifiers? Is it a choke or capacitor input filter? And also do you happen to know how they are wired? Fullwave, bridge, or what?
Nick
That thing has to be fun to just look at. I love to just study things like that. The way they built things back in the 30's to the end of tube only designs.
Do you know the a.c. Input voltage to those mercury vapor rectifiers? Is it a choke or capacitor input filter? And also do you happen to know how they are wired? Fullwave, bridge, or what?
Nick
Ive been meaning to reply to this thread for a lonnnng time.
I haven't had much of a chance to look at this wonderful amp
Returning to Uni and full time work in the run up to christmas doesn't leave much time.
However I might do some more investigating over Christmas, since Ill probably be the only one in anyway!
Im not familiar with that tube, Id say they're about the size of a 6L6, but a little like the stubby 6L6's, so not large.
have no idea, I should really investigate further.
It has a certain Steam-punk thing going on, for sure.
That I could find out, Ill have to dig out the schematic and post a picture, but im not sure if a 1955 Amp is even covered by copyright any longer...
Wouldn't want to post something and break the forum rules of owt.
Any kind moderator, let me know?
I haven't had much of a chance to look at this wonderful amp
Returning to Uni and full time work in the run up to christmas doesn't leave much time.
However I might do some more investigating over Christmas, since Ill probably be the only one in anyway!
Im not familiar with that tube, Id say they're about the size of a 6L6, but a little like the stubby 6L6's, so not large.
have no idea, I should really investigate further.
It has a certain Steam-punk thing going on, for sure.
That I could find out, Ill have to dig out the schematic and post a picture, but im not sure if a 1955 Amp is even covered by copyright any longer...
Wouldn't want to post something and break the forum rules of owt.
Any kind moderator, let me know?
Hey Mondogenrator,
I was wondering how you where doing. This time of the year no one has any time left, lol.
The 866 is a mercury vapour rectifier tube that can handle 5kvac at .25 amps. They can be had for cheap on ebay. Or just get a couple 872a tubes and be done with it. They handle 5kvac at 1.25 amps. But the have less loss across the rectifier when compared to vacuum rectifiers.
if its single phase the rectifier circuit would either be a bridge or full wave. But seeing all those tubes makes me think 3 phase even though its only 1kw output. With 3 phase you just have 3 rectifier circuits that are all identical. Nothing too crazy. I envy you. Fixing things like this are play time for me. Although to be honest for me it was tv transmitters and not a.f. Amps. But tubes are tubes.
Steam punk,,,, where are you going to fit the boiler and huge steam engine to run the long leg dynamo to power it, lol. Now that would be a sight.
have a safe Christmas.
Come to think of it those look like mercury vapour rectifiers. Plus there's 8 of them which makes me think a bridge rectifier with 2 parallel diode for each leg.
I was wondering how you where doing. This time of the year no one has any time left, lol.
The 866 is a mercury vapour rectifier tube that can handle 5kvac at .25 amps. They can be had for cheap on ebay. Or just get a couple 872a tubes and be done with it. They handle 5kvac at 1.25 amps. But the have less loss across the rectifier when compared to vacuum rectifiers.
if its single phase the rectifier circuit would either be a bridge or full wave. But seeing all those tubes makes me think 3 phase even though its only 1kw output. With 3 phase you just have 3 rectifier circuits that are all identical. Nothing too crazy. I envy you. Fixing things like this are play time for me. Although to be honest for me it was tv transmitters and not a.f. Amps. But tubes are tubes.
Steam punk,,,, where are you going to fit the boiler and huge steam engine to run the long leg dynamo to power it, lol. Now that would be a sight.
have a safe Christmas.
Come to think of it those look like mercury vapour rectifiers. Plus there's 8 of them which makes me think a bridge rectifier with 2 parallel diode for each leg.
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Hi nhuwar,
Yes indeed, there is aquivalent tube , the DCG5/5000. This rectifier is made by Philips. The suffix GB is a direct replacment for the 872A.
Data sheet:
http://www.mif.pg.gda.pl/homepages/frank/sheets/030/d/DCG5-5000GS.pdf
73
Wolfgang
Yes indeed, there is aquivalent tube , the DCG5/5000. This rectifier is made by Philips. The suffix GB is a direct replacment for the 872A.
Data sheet:
http://www.mif.pg.gda.pl/homepages/frank/sheets/030/d/DCG5-5000GS.pdf
73
Wolfgang
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