[ccomer1955]

Has anyone tried to rejuvenate 01A tubes using a battery set to apply voltage to the filaments? I was reading on a different, and inferior, forum that 15 minutes or so at about 6.3 volts can help marginal tubes.

I have also read that the process doesn't work as well on some manufacturers. My Freed Eismann NR-6 has a set of WARDS 01a tubes that measure in the low acceptable to low marginal range on my Triplett 2314.

So, the idea was to apply 6.3 measured at the filament pins with no other voltage on the set. Can someone explain why this is a horrible idea?

Don't worry, it is just a mental exercise.

[Ron Ramirez]

Do you have a tube tester? Depending on the tester, you can usually apply filament voltage only by setting the controls to leave the plate and grid disconnected.

I rejuvenated some 201A tubes from my Super-Zenith VIII a few years ago this way, and the process worked very well on all but one.

[Phlogiston]

I would not do it in a radio. You might overheat one of the filament control rheostats.

[ccomer1955]

Good point about the rheostats. Ron, I have a Triplett 2314. Would I set switch A to the correct circuit setting for an 01A, switch B (the filament) at 6.3 and switch C at zero while leaving the levers in the middle position (neither down nor up)? Then, go have a cup of coffee and check back in around 15 minutes later?

Here is a link to a photo of the 2314: http://www.radiomuseum.org/r/triplett_tu..._2413.html

[Arran]

The first thing I would try on weak testing 01As is to resolder the pins, especially if they are the older balloon types. Sometimes you will need to remove the bases to do this which involves melting the old putty with lacquer thinner to get them off, and then windshield adhesive to glue them back on, but try touching them up first to see if there is an improvement. The solder they used in the 1920s was not the best, and it gets worse with age. I've actually thought about making a test adapter involving a four or five pin base with alligator clip leads for testing early tubes with the base off, I'm running into flaky solder joints a lot with things like #24s and #26s. Nothing is guaranteed though, it may only work on some of the tubes or none at all, but until we can convince someone overseas to make new 01As you sometimes have to make do.
Regards
Arran

[ccomer1955]

They are all ST style tubes, but I will take a look at re-soldering the pins. I always like it when it turns out to be the little things that only cost time. I had a low performing Crosley 7H4, it played but had no volume, and I spent hours tracking down possible issues that would affect volume. One day, I removed all the tubes and cleaned the sockets and the tube pins, grid caps and grid clips. Put it back together, and suddenly no volume issues at all. I use that set pretty often (seven tubes); I'd use it more often if I could find one of those "fishing reel" tuning knobs for it.

Thanks for the suggestion, Arran.

[Phlogiston]

01As in a ST envelope will probably not "rejuvenate". Running them at an elevated filament voltage may actually make them worse. Running them at normal voltage and under load for a few hours my improve some.

[ccomer1955]

Well then. Looks like I'm probably going shopping for 01A tubes if the desoldering doesn't help