View Full Version : AVO Two Panel Tester
Just dug this out.
Tried to test a 45. Basically it doesn't work.
It powers up fine. Heater voltage set to 2.5V and looking at the filament that looks about right in terms of glow for a 45. Set 4V and it's too bright. I therefore believe it is supplying about the right heater voltage.
Anode is set to 100. Select anode set to normal. Set mA/V switch is set to mA/V marking.
With these settings it should be possible to set the meter to read zero. However, that's impossible and the lowest value I can back it off to is 4.8 mA/V. But then it slowly rises see 2nd pic.
The Philco 45 is working and known to be good. The switch settings for a 45 are correct according to the AVO Data Manual.
Conclusion is it is bust. I have known that for a long time.
Anyone on the forum know how to fix these meters?
Mod fix the title to AVO?
Cheers.
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Firebottle
05-07-2019, 13:53
I could take a look at it for you Justin old boy.
I like a challenge :cool:
Alan like the sound of that.
Will PM at some stage over the weekend.
Just spotted in a computer repair shop in Clifton...
Retro cool.https://uploads.tapatalk-cdn.com/20190707/b2df0311530503fcc37fc3a53c4f71a7.jpghttps://uploads.tapatalk-cdn.com/20190707/4cf76742fa109be9e6ae63d81d796f7f.jpghttps://uploads.tapatalk-cdn.com/20190707/cd95ff1bf0c52726f39edb2044ed5ea8.jpg
thingfish
07-07-2019, 12:12
A O Tester....?:scratch:
What....... Tests Amps, Ohms but no Volts.
A few internal shots.
Couple of caps which I suspect are from around 1938.
The main concern seems to be the state of the large tranny.
Alan please take a quick look. I don't know whether that looks repairable. Don't want to send it on if it looks doubtful. But we do know that large tranny supplies about the right heater voltage (amazingly).
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Some more...https://uploads.tapatalk-cdn.com/20190708/f3fa6927655bc016eb15b955452b41fc.jpghttps://uploads.tapatalk-cdn.com/20190708/9d42d800da49b34b54e67e8ec05c2c70.jpghttps://uploads.tapatalk-cdn.com/20190708/2ffdc60ab44c05c3b7d9a8bc3b382cac.jpg
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Firebottle
08-07-2019, 11:44
It looks old, it is old, with insulation materials to match.
I will definitely replace the two wax capacitors but I doubt there will be a problem with anything else.
OK will try and post out tomorrow.
The wiring insulation is shot in places. But I can't see anywhere where it would cause an actual problem. It may be prudent to correct the obvious issues where they can be seen.
I think the issues it has are deeper rooted than the two caps and wiring, so enjoy trying to suss it out:)
Firebottle
08-07-2019, 13:55
Does the unit have a 4 pin socket suitable for 211 valves?
If not have you a spare 4 pin socket you could send as well?
No it doesn't. And the only ones I have are in my amps.
It has a 10V heater winding on the tranny, though, as you have probably seen.
But I do have some excellent UX4 Teflon CMC sockets if I can find the buggers. It'd be good if you can slip one in instead of the current one.
The unit like most testers certainly won't be capable of testing a 211. Virtually nothing is. Most are sold untested on eBay for that reason.
Do some Googling and you will probably find some custom built add ons for Hickocks and the like.
On its merry way Alan. Just posted it.
Amazingly perhaps Alan has this working!:) Top marks.
Am sending him a 211 valve and base. With a bit of luck 211 testing will be possible. I have a large 211 collection so I reckon it's worth doing.
I also have a large triode collection e.g. 2A3, 6A3, 45, VT52, CX 345, AD1, PX4 etc and quite a few rectifiers. And countless smaller valves.
Back from Alan. Fixed he says;)
New box too. The 164XXXXXX. WTF?
:)
Will try soon.
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8 months old and 212 views. Definitely in the nerd category!:D
https://youtu.be/UHsH-5U_BrA
Firebottle
24-08-2019, 15:12
Back from Alan. Fixed he says;)
New box too. The 164XXXXXX. WTF?
:)
Come on Justin I thought you could have worked that out. It is the rotor settings for the tester for the 211 add on box.
X = don't care.
I know Alan it was a joke...:)
Thanks for doing it BTW. I hope I don't get disappointed when I start testing my valves.
Here we go Alan. That's a GE 211 in there. The meter reading is 2.4 ma/V same as the Chinese 211 I sent you and you measured.
That's good news. It survived the post!!!:)
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Now aptly named...
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Firebottle
24-08-2019, 21:57
Spot on :D
It is showing variance between 211 performance well after testing quite a few more.
Top job.
Firebottle
25-08-2019, 07:45
Excellent, i rather hoped it would after studying the valve curves.
Now aptly named...
https://uploads.tapatalk-cdn.com/20190824/88c4b02770ca3f423dbed814f9912062.jpgHa - cool Perid Dymo Tape too!!!
Sent from my G8441 using Tapatalk
Talking of periods I thought my collection of Amperex 211s were 1950s but some are dated stamped 1940 on the base in small print.
Why I didn't see that before I don't know. They are US made for the US Army.
The wife bought the Dymo recently. Surprised they are still made TBH.
Seems to work rectifier testing, too, Alan.
Tested three Chatham's. 20mA is NOS. FSD on the meter is 100mA in recti testing mode.
Tested my entire 211 collection yesterday. What really surprised me is the Amperex I have actually been using for years tested the strongest.
Found two lemons but I can put together very good quads of GE, Amperex and RCA.
Satisfying. Thanks again Alan.
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I can definitely state that some eBay valve sellers are lying through their teeth with claims about how well the valves they are selling test.
It isn't a prolific problem. But it is there. It's a 5 or 10% problem at most. But be very careful if you are spending a lot of money without a tester.
That said some brand new valves could measure better.
Some really old triodes can take about 5 to 10 minutes before they provide a stable output. Curious. But once settled they are fine.
Anyone know how to test a dual triode with a quoted mA/V figure greater than the 10 mA/V full scale deflection value the meter allows?
Is there a trick or is it basically not possible?
It IS possible to set it up so FSD represents 1mA/V. Not useful in this case.
E88CC is quoted as 13 mA/V in the data manual, which is the valve in question.
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