KEL80 Output Transformers

[sbellradio]

Going through my old DIY supplements, I came across the KEL80 monoblocks.

I am interested in building but I'm assuming the output transformers are long obsolete. Does anyone know the specifications?

thanks,
Steve.

[bob orbell]

Greg. is WD Archivist, he should see you post shortly and advise. Bob

[pre65]

I checked my WD Gold archive disc and can't find the details. I'll try and find my old pile of supplements.

I did have a pair of the power transformers for a while, but they went to help a KLE80 owner in distress.

It should be relatively easy to Google "EL34 in parallel push-pull 80W" to see what transformer impedance is recommended. I believe GEC might have done one in the past ?

Hammond would be a good place to start for ready made, but there are still transformer places that can make to order.

PS what is the supplement number ?

PPS I found supplement number 49 which has some info, was there anything later ?

[sbellradio]

Supplement 48 (Nov 1999) was the 1st part and 49 (Feb 2000) was the 2nd part. I don't know if there was anything later.

[John Caswell]

I've being trying to help Steve out, hence the thread here.
I have looked through the supplements but there is absolutely no info regarding the optX. Matthew cannot help either, so if anyone here has a KEL80 we could arrange to measure one of the opts.
In fact it might be an idea if we have various types of WD amps available to measure them and put in the FAQs I would be happy to do the measuring and it would probably take about 10-15 mins per amp.

John

[pre65]

Some few years ago I sold a pair of KEL80 mains transformers to a guy on this forum.

The relative posts are probably in the forum archives now, but if anyone can find out who the recipient was he might be able to measure them ?

As an aside, those mains transformers were stripped from a pair of KEL80 amps that were dumped in a skip when World Designs folded.Obviously someone must have "rescued" the majority of the kit and sold it to anyone who had cash. The man who I got them from purchased quite a few different amps and bits and pieces but he was not the skip diver.

I believe our Bob may have got some bits as well ?

[bob orbell]

I only had PCB 's, cases that had been used or damaged and a very poor KEL84, some capacitors also, the KEL 80 PCB,s went to Wieslaw Lipowski in Poland, to my knowledge he is the only one on this forum who still uses these amps, it could be worth a PM to him, he is quite helpful. Bob

[Richard]

Friend GerryB bought a pair of these when we went to a rally. One had a duff OPTX and we were lucky to get the last the Mike Holmes had when he bought the old WAD stock.

We fixed them fine and he had them a while. A few members had them when they came out, Pip and Rash come to mind.

They were Kel34 with parallelled output valves, running pentode mode with "compound" bias (a mix of part fixed and part cathode).

I'd guess the OPTXs were 3 or 4K, as the original Kel34 used higher than the 6k6 that might be expected, but don't have a figure.

If the spec was ever given it may be during that short period (a couple of years) when the OPTXs were listed as separate items for sale in the main part of HFW every month. So if anyone still has their stash of mags from the early 2000's many of the TXs were specced for impedance and current in there and the items listed did change so if you find the mags check them all

[Greg.]

April 2001 HFW gives the specs as Kel80 E/I parallel-push-pull output transformer. 95mm(w)x115mm(l)x133mm(h). Primary-secondary 4.6K-8 & 4 ohms, max o/p-80 watts, max current-250mA. Valves EL34, 5881, 6L6.

Steve, if you want to pursue this as a project, I can supply you with the original build instructions with diagrams and also a correction to, I think something published in the original supplement article. Just PM me your email address.

[pre65]

Originally Posted by Greg.

April 2001 HFW gives the specs as Kel80 E/I parallel-push-pull output transformer. 95mm(w)x115mm(l)x133mm(h). Primary-secondary 4.6K-8 & 4 ohms, max o/p-80 watts, max current-250mA. Valves EL34, 5881, 6L6.

Steve, if you want to pursue this as a project, I can supply you with the original build instructions with diagrams and also a correction to, I think something published in the original supplement article. Just PM me your email address.

Well done Greg.