UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - GZ34

turretslug · 16th Oct 2019, 4:37 pm

I suspect that some of the Russian NOS thermionic indirect FWRs that get hawked around as equivalent for various well-known Western types including the GZ34 are actually nearer to the 5Z4GT in characteristics- the GZ34 was a late-comer to the field and probably benefited from a lot of development in cathode materials and electrode mechanical precision and consistency. It was a notable high achiever as regards heater power vs. cathode current capability, also low forward voltage drop and as GJ says, it got better over just a few years. Perhaps Mullard/Philips could see HV silicon rectifiers inexorably breathing down its neck and tweaked it to reduce obvious shortcomings, such as forward voltage drop.

How arduous is the application in mind?- I'd be fairly content about using one of the low-cost Russian types from the auction site at, say, 300-0-300V and 100mA DC output current but if it was for medium-power amp use at something like 450-0-450V and 150mA output, I'd be a bit more fussy about sourcing.

16th Oct 2019, 4:37 pm	#9
turretslug Dekatron Join Date: Nov 2011 Location: Surrey, UK. Posts: 4,400	Re: GZ34 - recommended brands? I suspect that some of the Russian NOS thermionic indirect FWRs that get hawked around as equivalent for various well-known Western types including the GZ34 are actually nearer to the 5Z4GT in characteristics- the GZ34 was a late-comer to the field and probably benefited from a lot of development in cathode materials and electrode mechanical precision and consistency. It was a notable high achiever as regards heater power vs. cathode current capability, also low forward voltage drop and as GJ says, it got better over just a few years. Perhaps Mullard/Philips could see HV silicon rectifiers inexorably breathing down its neck and tweaked it to reduce obvious shortcomings, such as forward voltage drop. How arduous is the application in mind?- I'd be fairly content about using one of the low-cost Russian types from the auction site at, say, 300-0-300V and 100mA DC output current but if it was for medium-power amp use at something like 450-0-450V and 150mA output, I'd be a bit more fussy about sourcing.