Reducing the valve collection

[Richardgr]

A few years ago I acquired a lot of valves (around 4,000) with a valve tester I bought, and since then they have been taking up a lot of real estate in my home, still in the boxes I packed them in when I catalogued them.

Now I need to thin out the collection. I had thought there was a hobby/business there when I was retired, but now I see the writing on the wall and there is no real demand for any valves that are not exotic, or the standard audio types, and if selling audio valves, then it really is not that liquid a market.

When I did the first catalogueing, I grouped them using the Philips type letters, e.g. 'C' for triode, 'CC' for double triode, 'CL' triode/output pentode, and so on.

I have sorted out the L's, F's, CL's, C's and CC's, but it is not so obvious what are good candidates for future projects amongst the CF's. Anything vari-mu has been discarded (e.g. PCF805), but I need to keep on slimming the numbers, and wondering what other valve enthusiasts would hang on to, with half an eye on a future project.

The ECF82 is a good candidate - has been used in some well known audio amps - but are there any others?

[Richardgr]

What I have learned so far ...
ECF80 has been used by some manufacturers as driver + phase splitter.
PCF82 is nothing like ECF82.

There is a useful resource where many of these types are tested and compared: MV Audio - Tube Data Library

Vari-mu variants are best discarded, e.g. PCF201. They can be usable in certain linear regions of the curves, but the better valves are available and cheap, so they are not worth keeping.

Common cathode types hard to make use of, e.g. PCF80, PCF806, PCF86.

There would not seem to be that many types worth hanging on to ...
ECF82, PCF82, ECF802/PCF802, PCF200 are keepers.

[Radio Wrangler]

You may be looking at them with an audio-centric viewpoint. This is a general forum and there are people here who treasure valves designed for radio or for TV purposes. Variable-mu valves aren't wanted for audio stages, but AGC amplifiers in radios and TVs are designed around them. Common cathode double valves have RF applications where it isn't a show-stopper.

There are valves in current production serving a lot of audio applications, though not particularly old styles like directly heated power triodes. On the other hand, virtually no valves re currently produced outside of the audio types. If you're interested in valved radio, then the current stocks od NOS and used devices are likely to be all that there will ever be.

David

[Richardgr]

Hi David, yes you are correct.

Part of the justification for acquiring those valves in the first place was that I could ensure they go to good homes.
The ones that I do not think I will ever use for one of my projects get put in a box, and boxes of 80 are listed for 30p (the minimum fee) on a local auction site, and so far they are finding new homes. I have even made about £50 from 700 valves.

Thanks to the robustness of valve technology, the days before 'just in time purchasing' and the rapid ascendancy of new technology for TVs, there are many hoards like mine all over the world, and countless replacements for the generic TV types.

If anyone here has a particular need for nonodes, heptodes, vari-mu pentodes or detector diodes, I will happily look out for them and pop them in a jiffy bag.

I am actually trying to promote the use of non-audio types for audio projects. I am looking at some simple PCBs that I could supply with TV tubes, e.g. PCL200, PCL82, PY88, PCF200, so they are used in projects.

[Craig Sawyers]

Originally Posted by Radio Wrangler

though not particularly old styles like directly heated power triodes
David

The directly heated Western Electric 300B power triode is being remanufactured.

https://www.westernelectric.com/300b

You read that right. $1500 for a matched pair, and twice that for a matched quad.

Craig

[GrimJosef]

Originally Posted by Craig Sawyers

The directly heated Western Electric 300B power triode is being remanufactured ...

As are a few 'trawler triodes'

e.g. the 211 https://www.tubeampdoctor.com/en/psvane-211-hifi-series

and the 845 https://www.mcru.co.uk/product/elrog-er845-triode-valve-tube/?v=79cba1185463

and at a smaller scale the 2A3 https://psvane.co/products/psvane-horizon-series-2a3-at-vacuum-tube-amplifier-matched-pair-2-pack.

Cheers,

GJ

[kalee20]

Originally Posted by Richardgr

What I have learned so far ...
...
PCF82 is nothing like ECF82.

They're not the same (other than the heater which obviously isn't!), but to be fair they are not hugely different either. The pin connection is the same, and the specifications, while different, are reasonably similar.

The mu of the triode is listed as 35 for the PCF and 40 for the ECF; and the mutual conductance is 5.5mA/V for the PCF at 10mA anode current, and 5.2mA/V for the ECF also at 10mA anode current.

I'd bet that given a tweak to the heater supply, either would work as a drop-in replacement for the other. The interelectrode capacitances are similar, which is a fair indication of similarity of construction as well as being important in the VHF frequency changer target application!

[Richardgr]

Yes, you are right, not sure where I saw the differences then! The valve data sheet even says 'For further information and characteristics see ECF82'. Now it gets an extra star in the spreadsheet

[Joe_Lorenz]

I have been keeping some "odd" valves like AK2, EH80, PCH200 just because almost 50 years ago we used these for audio purposes: To exercise building some synthesizers! Said valves could be used for modulators, mixers and the like. We truly produced some sounds that no-one of us had ever heard before. Unfortunately everything has been scrapped in between but the valves.

Joe

[Maarten]

Originally Posted by Richardgr

I have sorted out the L's, F's, CL's, C's and CC's, but it is not so obvious what are good candidates for future projects amongst the CF's. Anything vari-mu has been discarded (e.g. PCF805),

I hope by discarding you mean selling them off (cheaply)? Especially if they're new in box.

[Richardgr]

See above.

Part of the justification for acquiring those valves in the first place was that I could ensure they go to good homes.
The ones that I do not think I will ever use for one of my projects get put in a box, and boxes of 80 are listed for 30p (the minimum fee) on a local auction site, and so far they are finding new homes. I have even made about £50 from 700 valves.

The exception to the rule are EHT rectifier pulls, e.g. DY82, GY501. They go in the 'tested and below minimum' box for eventual safe disposal.

[Richardgr]

Originally Posted by Joe_Lorenz

I have been keeping some "odd" valves like AK2, EH80, PCH200 just because almost 50 years ago we used these for audio purposes: To exercise building some synthesizers! ...

Joe

I have put aside some ECH83 (and the ECH81 which is meant to be similar) to build some effects pedals.

I had a lot of Telefunken diamond marked EH900S, but they went to good homes.

The 10 pin valves, like PCH200, are a harder sell. The curves for a PCH200 are here:
Triode part
Heptode part
... and the verdict was 'useable', so it will go in the 2 star box.