Recent content by chrisW

Conversion using UF5407 800V 3Amp 2-Pin DO-2 Soft Recovery Ultrafast Plastic Rectifier Diodes in a standard octal plug with the cap off of a fabric conditioner bottle a perfect press fit to finish it off :grinning:

Two parallel 1K 5W resistors in the B+ gives me 325V at the rectifier and 320V on the plate. I might need to add a 600 Ohm or so resistor into the bias, as with the new diode in place of the selenium the lowest it will adjust to is -13.1V. Not to sure what would be best, about 12.5V at a guess...

After much fiddling I have managed to dismantle the selenium rectifier and rebuild it using UF5407 Diode 800V 3Amp Soft Recovery Ultrafast Rectifier Diodes. So it now looks original.

Stone me!! I knew the Frank 30 amps' were rare now and expensive to get hold of one. But I didn't know people would pay this much for one. I found this while doing a deep Google search for data on the amp' I'll not be selling it though :^)

If anyone needs valve radio data sheets, you can download them free from my server here: Valve Radio Data Sheets

I have other 60s nice looking and working kit to keep you amused like this stereo valve radio. Details here: Radio Museum Data

I have two more valve amps but they are modern Chinese amps' with PCBs neither are integrated, so no phono preamp, and you can easily hear the difference in the sound. I bought them to experiment on, to see if they could ever match my 60s kit....... Not a hope in hell :grinning:

Here is another one of my pride and joy amps'. This one isn't quite as good as the Frank, but still a great sounding amp'. This one has been completely rebuilt with all new caps and resistors, bar the wire wound resistors. Both amps have all matched quad & pair Russian military gold grid valve...

Thanks for the advice, but I've been playing with this stuff since 1964 when I left school and started earning. Still have all my finger, not too sure about the marbles though :^)

Yes, valve equipment and printed circuit boards are not good bed partners. It's very difficult to design a printed circuit board to keep all the high voltage stuff from injecting interference into the signal path, especially in a fully integrated amp'. Also to stand any chance of getting a...

Hi Gray, Thanks for that..... Done :^)

I have a FRANK pram 30 watts Ultra-linear Stereo tube amplifier, in which I am replacing the selenium full wave rectifier with a diode full wave rectifier, I am also replacing the selenium bias rectifier with a diode, as well as replacing the electrolytics. The details of the amp are below. I...