Linehand
Active Member
I picked up this tester (emissions, shorts) to go through some tubes I found in an abandoned organ- mainly 12au7 and 12ax7. This checker lists two sets of testing parameters for this tube and all tubes will pass the test one way, but most fail the test in the second (only 2 out of 20 pass both tests).
I can physically see that both elements at the top under the getter are glowing in the tubes that pass, but all others that fail only show one side glowing under the test.
If these tubes are placed in circuit in my amplifier, both sides will glow.
I'm assuming its an issue with the tester but find it strange that a couple tubes pass the test. I did replace some out of tolerance resistors and successfully tested several output tubes, one of which was known bad, and the tester indicated a short.
Anyway, I'm really just experimenting and learning as I go - what should I be checking? The signal tubes are RCA and Sylvania 12A_7's from the mid 50's
thanks
I can physically see that both elements at the top under the getter are glowing in the tubes that pass, but all others that fail only show one side glowing under the test.
If these tubes are placed in circuit in my amplifier, both sides will glow.
I'm assuming its an issue with the tester but find it strange that a couple tubes pass the test. I did replace some out of tolerance resistors and successfully tested several output tubes, one of which was known bad, and the tester indicated a short.
Anyway, I'm really just experimenting and learning as I go - what should I be checking? The signal tubes are RCA and Sylvania 12A_7's from the mid 50's
thanks