I have tested some 6AV5GAs on my EICO 666 and they give wild results. I've tried several settings based on different versions of EICO charts, but wondered if anyone had the 'correct' lever settings etc.

I define wild as loud hum from the PT in the EICO, needle slamming on one leak test, and almost no gain. Both tubes tested identical, which makes me suspicious of the EICO settings. I know replacements only cost a few bucks, but a shame to junk any good tubes. These are in a Bogen I am starting to restore, but I've not yet powered the amp up, which I guess would be the 'real' acid test anyway.

Situations like this are part of why I have several different testers.

Incorrect published tube test settings aren't unheard of, by any means. My Weston 981 roll chart settings for a 6BQ5 were incorrect, producing results not unlike the ones you describe. Other testers showed no problems with the tubes under test, and neither did in-circuit tests. Later on, I got hold of some supplements for the 981, showing different 6BQ5 settings, and these worked.

Yes, the acid test is how the tube functions on the job, but under the circumstances, I'd proceed with the utmost caution. Frankly, I would defer in-circuit testing until I'd run those 6AV5 tubes across at least one different tester and cleared them for trial in your amp. Otherwise, if the tubes are defective, you may be risking expensive output and power transformers, among other things.

Best of luck with your project.

Larry

Often you can figure out what the tube tester settings should be by looking at the tube basing diagram and knowing what general type of tube it is. Do the recommended settings you are using appear to match the tube's pin assignments?

-David

is 6AU5 or 6FW5 listed? Same base pattern and quite close... or for that matter, see if 12AV5 or 25AV5 have different settings (other than heater, of course). 6BD5 and 18A5 also have the same base but less heater power, so 6AV5 will read REALLY high on those settings.

I ended up using these settings from the 1978 Coletronincs data.

Fil= 6.3
Grid= 10
Plate= 80
Levers 1-5: 5 1 1 1 4
Levers 5 - 10: 1 2 3 1 1
V= 4
S= 1
Leak= 1 3 5 8
Merit= 5

With these they tested borderline OK. In the yellow between good and bad... No leakage, and not gassy.

Tweaking plate/grid of course alters the readings, which is expected, but unless the values stated in the data sheet are correct, it's difficult to be 100%. Since they are cheap tubes I'm not too worried

One of my 3 Eico's (2 667's, old & new style, & 1 666) still hums loudly using the corrected settings you list above, so to eliminate humming and still get test results on 6AV5, I have changed switch setting on pin number 5 from "4" to "3". It's interesting that some perfectly good Eico 666 and 667's hum like crazy but other units don't hum at all. Previous discussions explained that this variation can be caused by small differences between transformer windings, laminations, or transformer mounting into the case.

As I mentioned in a different post on this amplifier, if you need new tubes order 6FW5 which has higher power and voltage ratings but run without any circuit changes. In my Bogen they seem very rugged. Only $4 as there is no demand, they were only used in B&W televisions.
Don

Don,

Where do you see them at 4 bucks? I can only find them at $9.95, which is twice as much as the 6AVs.

Thanks,

N

Here they are, at Vacuumtubes.net, http://www.vacuumtubes.net/Prices%206C%20to%206LY8.htm
I have bought other tubes from there.
Order extras if you want to try to match them for idle current. etc. They are sweep tubes which are very linear.
Don