[Hallicrafters] When do you replace tubes?

[Jim Brannigan]

I replace tubes when the device does not meet published specs AND the tube
is suspect.

Jim

> Hi,
>     My question is when do you replace tubes in Hallicrafters receivers.
>   I use a Hickok 6000A tube tester which is a dynamic mutual conductance
> and reads out Gm.  As an example in a SX-100 receiver I'm working on I
> read some of the following measurements:  For a 6AU6 (book value) 2300
> (measured) 1475 or 64%, For a 6C4 (book) 2200 (meas.)1700 or 77%, And
> for a 6SC7 (book) 1000 (meas.) 350 & 200 or 35% & 20%, and so forth.
>     My inclination is to replace any tube below 75% Gm reading of a new
> tube.  What are other opinions?  Thanks.
> 73,  Skip Magnuson  W7WGM