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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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4th Feb 2009, 5:59 pm | #1 |
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Ancient Ekco Power Unit (AC10/20)
Hello everyone again.
This is another fishing expedition among your extensive knowlege. See attached pictures. I came across this accidentally. However, here it is, at a good home. It's about 9" x 5" x 3 1/4 deep, and made of brown Bakelite, slightly cracked. There's a hand-written label stuck on which says 1920s. On the back is stamped:- AC 10/20 4251 REGD. 782513 PAT No. 262567. There's also a Westinghouse Patent label which I hope you can see in the picture. Also on the back is a mains voltage selector and a 'mA' selector. On the front are a range of sockets - again I hope you can read them. I haven't tried to do anything with it yet. As you can probably see the mains cable has been cut off, and anyway its insulation is falling off. The rectifier measures about 100k in both directions and the choke (?) measures about 50k. The triple electrolytic shows no sign of 'charging' from the AVO. My guess is that it's meant as an HT Battery Eliminator. I've read the Thread on battery eliminators, but they seem much more up-market than this one (I really like the idea of chargeing the accumulator when the radio is off!) So, before I'm tempted to do anything silly has anyone come across a similar one? When was it made? Is that a Copper Oxide or Selenium rectifier? What is the purpose of the 'mA' selector on the back? What would I expect from the various sockets on the front? etc, etc. Here's looking forward to some interesting posts. Alan Last edited by Station X; 4th Feb 2009 at 6:18 pm. Reason: To comply with forum rules. |
4th Feb 2009, 6:21 pm | #2 |
Nonode
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Re: Ancient EKCO Power Unit
You are right Alan. This is a 1930s battery eliminator. If I recall correctly there was a thread on these a couple of years ago.
This was what the E K Cole company, better known as Ekco, started out manufacturing. They were made for years. This one looks to be in good condition considering its age. Regards,
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4th Feb 2009, 6:28 pm | #3 |
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Re: Ancient EKCO Power Unit
Brian,
Ah, you think it's 30s. OK. I did wonder because of the rectifier. When were they invented and when did the Westinghouse Patent run out? A couple of other thing I forgot to mention: The whole thing is held together with Aluminium rivets, which make it very difficult to get at anything. Also, there are a couple of 'variable' resistors tucked under the top panel. They appear to be carbon rods with sliders. Alan |
4th Feb 2009, 6:32 pm | #4 |
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Re: Ancient EKCO Power Unit
First time I have actually seen one of those. Battery eliminator as Brian says. EK Cole originally made Bakalite mouldings and started producing these when all the houses were built in Southend with mains electricity, most people still had battery sets so the demand was huge, they really made Ekco.
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4th Feb 2009, 6:36 pm | #5 |
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Re: Ancient EKCO Power Unit
Rivets can easily be drilled out and replaced with nuts and screws if necessary.
S.G denotes Screen Grid Supply. The other supply is HT to the anodes. H, M and L denotes High Medium and Low. It might be useful to reverse engineer the unit and produce a circuit diagram.
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4th Feb 2009, 7:20 pm | #7 |
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Re: Ancient EKCO Power Unit
Graham,
Yes, but it's always a bit fraught. I'll have to do it in the end, I was just hoping someone had already worked it all out. Darren, That's a splendid link. Perhaps the 10/20 relates to the current 'link' on the back. But what changes when the link is changed? I fear the reverse engineering will be the only anwer. Alan |
4th Feb 2009, 7:25 pm | #8 |
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Re: Ancient EKCO Power Unit
I've one somewhere in the same case, but can't remember exactly what it does (or did ). I expect the mA settings at the rear are for adjustment according to the anode current demand of the output valve in use, to maintain the expected voltages at the various front panel sockets.
Paul |
4th Feb 2009, 7:40 pm | #9 |
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Re: Ancient EKCO Power Unit
Paul,
That's logical - a sort of crude method of maintaining 120 volts (say) at different loads. However, I can't see any extra resistors. I've just noticed that the 'mA' selector is on the 'output' side of the transformer, and there appear to be 4 'output' wires (see picture) so perhaps it simply changes the output voltage. Bearing in mind that the losses from there on will be pretty constant a bit more voltage from the transformer would allow more current to be drawn at the same output voltage. Alan |
4th Feb 2009, 8:34 pm | #10 |
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Re: Ancient EKCO Power Unit
I reverse engineered a similar Regentone W1F battery eliminator a few years back. If you've got Paul's Service Data DVD you'll find it on there.
Not very complicated. Mains Transormer, Rectifier, CLC filter and a few resistors.
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4th Feb 2009, 9:20 pm | #11 |
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Re: Ancient EKCO Power Unit
I expect someone thought it was 1920's because it has a 7xxxxx reg. des. number. The rule of thumb is 700,000's were 1920's
( according to an antiques guide I saw once). Maybe the design WAS late 20's so it's very possible actual item early 30's? Nice thing though.
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4th Feb 2009, 9:26 pm | #12 |
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Re: Ancient EKCO Power Unit
Graham,
I fear I haven't got Paul's DVD. However, I suspect that's not worrying him much as I keep buying individual ones! Also, I've got some books which cover the era I'm most interested in. Tim, That's brilliant. I never thought of looking at it that way. Alan |
4th Feb 2009, 9:44 pm | #13 |
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Re: Ancient EKCO Power Unit
Just found a summary of RD nos. at http://www.great-glass.co.uk/glass%20notes/regnos.htm , according to which 779292 is 1933's earliest known number and 789035 the earliest for 1934. 1933 does sound right to me for this one, I think the bronze case Ekco units tend to be a little older.
Paul |
4th Feb 2009, 10:02 pm | #14 |
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Re: Ancient EKCO Power Unit
I have an Ekco K12 in daily use. It's very simple inside. Charges my 25AH Cyclon at about 150mA. Switch on top switches between charging voltage and HT out when the set is to be used. Transformer and choke inside mine look a bit more "modern" than those pictured in the link. I wonder when Ekco stopped making eliminators?
Ian. |
4th Feb 2009, 10:14 pm | #15 |
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Re: Ancient EKCO Power Unit
Paul,
Thats splendid. I think that nails it down nicely. Ian, That looks very swish. What is the HT output, and at what current? I'm just interested about what I might expect. Alan |
4th Feb 2009, 10:34 pm | #16 |
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Re: Ancient EKCO Power Unit
I have one of the earlier Ekco HT only units, a No2 A10, Possibly from 1926 as shown HERE , All original with a long copper oxide rectifier, Still gives it's rated output of 10mA at 120v.
Regards, Mick. |
4th Feb 2009, 11:07 pm | #17 |
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Re: Ancient EKCO Power Unit
Alan,
The K12 is rated at 12mA. At 10mA, the voltage from mine is 125 volts which is about right for a new 120 volt HT battery. The 12 mA rating on the HT output is reduced if you are feeding a screened grid at say 1.5mA from one of the other sockets. My radio uses a 220OT and this psu suits that quite nicely. Suffice it to say that I have never had to remove my accumulator to charge it and it's been in operation for nine months and used daily. The K12 remains as cool as a cucumber, probably as a result of snipping the wires to the metal rectifier and replacing with a 1N400 something. Also gutted the can with the reservoir/smoothing caps in and replaced with modern and much higher capacitance units. Then refilled with wax. Fitted new mains lead and grommet, replaced charger output leads. Added loading resistor to keep off- load HT voltage at about 150 volts. Thought about zenering output to 130 volts, but it would not be as original then. All in all I am pleased with it. Well worth getting yours going especially if you have a 1930s radio to run from it. |
5th Feb 2009, 12:05 pm | #18 |
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Re: Ancient EKCO Power Unit
Gentlemen,
That definitely answers my question about what to expect. As far as a '30s radio is concerned I haven't got one at the moment. My earliest memories of radios, from the '50s, when we lived in a house with no mains suppy, was of just such a set. We had two accumulators (one was being recharged at the local cycle shop while the other was being used), plus of course a GB battery and a steady drip of HT batteries. My parents used to complain about the cost of the HT batteries! So I guess my next step is to carefully take it to bits, sort out the circuit and fix what needs fixing. Then, a battery set to try it with. Mods, I think I probably put this thread in the wrong place as usual. I'd like to keep it going as I'm likely to need some more advice and guidance as I do the job. Could you move it to a more sensible place please? Alan |
5th Feb 2009, 2:26 pm | #19 |
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Re: Ancient EKCO Power Unit
From a 1933-34 catalogue.
John |
5th Feb 2009, 2:58 pm | #20 | |
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Re: Ancient EKCO Power Unit
Quote:
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