[Hallicrafters] Testing tubes

[Radio Randy]

Barrie,

I would be more inclined to believe that the high reading is more an issue
with the calibration of your tester, although that may be wrong. Also, I
wouldn't worry about those tubes glowing brightly upon turning the set on.
The inrush current is always higher with cold filaments until they balance
out.

If there are any opposing views on this, I won't argue with them. It's been
a while since I've really played much with the older gear.

Radio Randy

----- Original Message ----- 
From: "Barrie Smith" <barrie at centric.net>
To: <hallicrafters at mailman.qth.net>
Sent: Sunday, September 28, 2003 2:03 PM
Subject: [Hallicrafters] Testing tubes


> Attempting to discover why an old Luxman tube-preamplifier didn't sound
too
> good, I drug out the Hickok Cardmatic tube-tester this morning.
>
> I noticed that 6 of the 7 12AX7s tested off-scale (to the right, above
100).
> New 12AX7s that I tested ran from 80 to 90 on the scale.
>
> Is there a problem with an off-scale reading?
>
> There was no indication of leakage or gas in any of the tubes.
>
> Also, all of the tubes that tested off-scale had another characteristic:
> Upon powering them up in the tester, the wires in the base that evidently
> connect to the cathode lit up bright red to almost white for a short
period
> of time, perhaps a second or two.
>
> The new tubes that I tested did not exhibit that characteristic.
>
> Any thoughts on this subject?
>
> 73, Barrie, W7ALW
>
>
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