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    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

How to test a subminiature tube

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dayveshome

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Joined 2002
#1
I recently thought of a project for a subminiature tube. I have a small supply of JAN6418 subminiature tubes I purchased a few years ago. The question is: How do I test these. I own a B&K model 707 DynaJet tube tester. The tube is not listed in tester charts, is there a way to make a converter to test these little tubes? Thanks in advance!
 
#2
While a 707 is a nice tester (I have one) it's a semi dedicated tester to the tubes listed and has no submin socket. The 6418 takes a maximum of 30 volts. Even if you had a submin to octal adaptor, you would have to lower the plate & screen voltage with an external network. The drive signal may also have to be lowered. Then test several known good ones and develop a curve. Not very practical. Many of the better Hickoks have a provision for a low voltage test of these subminiature tubes.
 
#3
Tester replacement model?

Thanks HollowState for the advice. I've had this B&K tester for years and years, it's been very adequate. I'm starting to have problems with it so now is a good time to perhaps replace it. Any suggestions on which Hickock model would be a good choice for submini's and more conventional tubes?
 
#4
dayveshome said:
Any suggestions on which Hickock model would be a good choice for submini's and more conventional tubes?
Click to expand...

Well, both the 539C and 752A will test them. They have compactron 12 pin and novar 9 pin sockets too. The older 533/A, 534, 539A/B & 752 also will but are minus the two sockets just mentioned. (you'll need adaptors) And the 6000/A probably will as well as the KS (Western Electric) version of the 539B will. But remember, not all submins require low voltage testing like your 6418s. I happen to be familiar with these tubes because they are used in some older General Radio and Keithley instruments.
 
#5
Hi davyshome ,

HollowState gave excellent tips about Tube Testers . But if you want a lot of information
about this subject , I recommend the book :
" Tube Testers and Classic Electronic Test Gear '' by Alan Douglas ( Sonoran Publishing -
2000 )

Regards,

Carlos
 
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