Tubes Asylum

Question for EICO 667 tester experts.

176.237.16.17

hsuha

When I apply the stttings as described in the printed manual to test a 6550 tube, voltages are 6.3-15-90...but I cant get a logical result.Even new tubes fresh out of box measure %90..When I set the last number to 96 instead of 90 then the measurement seems OK..What do you think?In my country there is no place to get it calibrated..

Follow Ups:

RE: Question for EICO 667 tester experts. - PeterI 16:24:58 11/25/14 (1)
This may be encouraging: When I tested some older used US Tung-Sol 6550s they were around 88-90% on my Eico 667, a bit disappointing. But when I got the Hickok tester the same tubes tested very high, and with trustworthy readings. I did use KT88 test data (all Hickok supplies). I suspect the 667 is a bit off for 6550s.
Pete

Edits: 11/25/14
- RE: Question for EICO 667 tester experts. - hsuha 16:32:13 11/29/14 (0)
  Thanks for the reply..I tested some new tubes and changed the settings.
  I changed the V-S settings to 4 and 1 instead of 3-1 and I increased the plate voltage to 96 instead of 90..Then I started to get some satisfactory results..What do you think?...
Easiest way to fix - Chip647 07:44:17 11/25/14 (0)
1. Measure a few new tubes of the types you use.
2. Calculate the average value and write it down on a 3 x 5 note card.
3. Use that value to judge tubes of those types against.

Most tube testers are relativistic anyway. I have constructed one based on Steffy Bench's design that gives precise Transconductance and Mu measurements, however I do not use it much because it does not really matter. If I purchase a lot of old used tubes, I will pull it out to cull the heard of shorted and nearly dead tubes. I can generally tell pretty quick if I like a tube and if it is performing correctly by listening to it.

Don't fret the numbers. If you are measuring to sell tubes, just add the following words: "Tested on my EICO 667 and test better than new at 107%, no shorts." (like everyone else does). :-)

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