Jackson 648 is a good quality emission tester. It does not measure mutual conductance, aka transconductance. "Dynamic"
means they saved money on power supply filter caps and ran everything on unfiltered, full wave rectified AC.
"Conductance" without "Mutual" or "trans" ahead of it means "emission".

See Alan Douglas' "Tube Testers and Classic Electronic Test Gear", available at AES.

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"A F Four Kilo" wrote in message ...
FOR SALE:
Jackson Dynamic Conductance Type Tube Tester - Model 648

Excellent condition with built-in roll chart.
Has almost all type of tube sockets and will test
a very broad variety of tubes. This is not just an
emission tester like most tube testers.

This is a full-feature transconductance type tester.
115V AC operation, with a good power cord.
Unit is in excellent working condition.
Will sell for $99.00 plus shipping.

E-mail:


and Remove that NOSPAM

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