Grundig 80U

[Amie]

Amie, I presume you're now back from the USA. Hope you had a great time.

Data on the ECL113 can be found here: http://www.mif.pg.gda.pl/homepages/frank...ECL113.pdf and here: http://www.mif.pg.gda.pl/homepages/frank...ECL113.gif  Not a valve I've encountered before.

Initially I'm more concerned that the set was tripping an RCD. An isolating transformer will certainly stop that happening but doesn't solve the problem.  A bench mains supply really needs its own RCD so when it trips you don't annoy anyone else. Not always possible but something to bear in mind. The power supply arrangements in that set are interesting.  A transformer to supply 6.3V heaters plus halfwave rectified HT straight from the mains. The sort of set that's live chassis but might fool people because it's got a mains transformer.

Hello Jeffrey.
Yes, just home. Thanks had a fantastic time, it was great to see my friend again, I was sad to leave

I had started on this before I left on holiday, but am now interested in getting on and fixing it if I can.

The setup I use for powering is an isolating transformer with one side of its output earthed separately from the mains earth and an rcbo on its output, one of dad's bits of kit, I don't think the radio tripped the rcd, just the mcb.

I've read that you can't just replace the original selenium rectifier with a modern diode in a mains derived supply and that it should have a series resistor, this set had already had a silicon diode put in with no resistor and had proven that point. What value would be good?

The grid to cathode voltage (triode section) is zero, but there's no short. It should have a small negative voltage, I would have thought? Its cathode is common with the pentode, and that seems to work fine.

Thanks for the info and PDFs

Amie