tubes age 24
the tube characteristics change because of a different gas pressure, the tube
can
stop conducting which lets the voltage rise up to the trigger voltage then the
voltage drops while the tube takes current... A zener diode at the same voltage
is not as fine a regulator. My solid state circuit that I've not yet bread boarded
would do much better. Need to try that some time.
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Date: Sat, 22 Jan 2000 20:33:13 -0500 (EST)
Subject: Re: [R-390] Spurious Intermittent Help...
Apparently voltage regulators fall into a group of tubes that can't be tested
definitively-- or at least that's what I infer from the second page of the Test Data
for Electron Tube Test Sets TV-7/U through TV-7D/U, TB-11-6626-274-12/1.
Sure, you can get an idea of the tube's emission or discharge characteristics,
but read the following quote. YMMV:
Note. The meter indication for tube types such as pentagrid converters, mixers,
thyratrons, and regulators (listed below) is not a true and conclusive
measurement of the tube condition and value. In some equipments, it is
necessary to substitute a known good tube of the same type to obtain a true
indication of the tube's condition. Do not discard a tube which does not operate
satisfactorily in the equipment, if the test set indicates the tube is good. The
tube may operate in another circuit. Thus endeth a reading from TB 11-6625-
274-12/1. Following the note is a
list of the tubes alluded to. 0A2's, 0A3's, 0B2's, etc.,plus over eighty other types
are included as well as the 26D6 (for you R-392 mavens).
Moral: Tube testers in general are not definitive, but a helpful guide at best.
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Date: Sat, 22 Jan 2000 21:18:18 -0600
Subject: Re: [R-390] 0A2 testing
>If a VR tube shorts, the output voltage goes to ZERO because its a shunt
>regulator and the dropping resistor begins to leak smoke.
I had a massive brain fart on that one Doc. I'll blame it this really groovy opiate
laced cough syrup. <grin>
(14 pages)
(10 pages)
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