Hi Oli, I guess I'm a 'never give up' on a valve type.
I have had "dead" valves come back to life simply by running them for a time.
Seems to allow an electron emitting surface to 're-activate' after being unused for decades.

Marc may have had some experience there or comment?

Also, I test such a valve in some sort of bench rig where I can easily meter what sort of current can flow from plate to heater.
I use a typical 385/385 power tranny hook it all up on the bench with series resistors in the plates and heater output into a load.
The voltage drops across the resistors then translate into Ma.
A common like PW10 x 100 ohm is a good value.

I've left valves sitting for hours hoping and praying and occasionally get a surprise.
The current drawn by the heater may also give a clue to the envelope being under vacuum.
If the current draws a value that then drops to a lower value once heated that could indicate 'normal' vacuum.
Unfortunately i've never had a large rectifier and done that test, just with 5y3 size.
I've 'resurected' filment output like 45 and cathode signal valves like 57.

A lot of trouble unless it's the last bottle 5AS4 on earth!

Fred.

Ian:
Thank you very much! I'd really appreciate that.

Fred:

I guess it wouldn't hurt to try to "rejuvenate" the valve by running it on around 10v on the heater?
But, like you said, a lot of trouble.

Really I just wanted a new (old) one!

Oli

I was rather lucky. Very early in what was then a hobby I scored a 1938 Paton VCT Valve and circuit tester 240VAC 6VDC. Since repairing its meter movement, it has been handy for years, as it can test valve radio tubes except miniatures. Caps resistors & also has a bonding meter.


Later I acquired a Tech that could test miniatures as long as you used an isolation transformer which I moved on, with warning, when a retired Radio guy I knew for ages gave me a 110V Knight 600 Tube Tester. I might run a tube for a while, but that's normally to speed up the Araldite curing when I re glue the base on a cold night.

Tip once you have run a bit of Araldite around the base. Use insulation tape, sticky side in to hold it in place; Until it finishes reacting.

The old "Radiotron Handbook" does not list 5AS4 as its a newer tube. However:-

5Y3 550V in 4μF 8k load is 72mA per plate good & 58mA at end of life.

A hefty 5U4 550V in 6μF 3550Ohms load 141mA per plate good and 113ma at end of life. 1000 ohms series, one volt across the resistor = 1mA

I glued the bases of the ones I have. GT & ST-14 envelopes.

Now! The overlooked method of sorting it out. If the tube is a dud.

Almost plug &play. For the cost of posting. I send you the two I will likely never use.

Hi Marcc,

Very interesting!

Thank you very much! Send me an email (address is unhidden) and we can sort something out.

Oli

Hello again everyone,

All solved! Thanks Marcc for sending one over.

The set runs nicely now.

Oli

Should have been two a GT & ST-14. Both in that chopped up padded envelope in the box?

Yes, sorry, two. Is ST-14 the name of the cylindrical glass envelope?

Tried to post this two days ago. Site locked up & would not reload until today.


To my info: The metal tubes will tend to be, as an example, Metal 6B6; Glass 6B6G and the tubes with straight sided glass 6B6 GT.

There were variations over the years S17 the balloon is 1933; ST-14 around 1935; England has U50 and Brazil, GT 1946, and I think there was an S

The ST-14 is the fancy one and the GT the one with the gassy looking getter. As pointed out to you. Valve tester that does not list it felt that they both worked. We know now one does.

Ended well, that's all that is important.”

Marc

I had the same issue Marc, but you've answered it well.

Here is my "backed-up" answer:

No, the ST-14's the coke bottle shape.

With octal valves you can generally tell by the full type number using the suffix. Examples:

No suffix = original octal metal tube.
G suffix = ST-14 shape (original glass bulb, a carry-over from the previous "UX" tubes. G stands for "Glass".
GT suffix = Glass Tubular.

Peter Lankshear's "Discovering Vintage Radio" Has photos of several varieties. I note that in a box of vintage tubes from a deceased estate,
I have scored a blue Arcturus valve.

Photos uploaded to Post 36.