[Boatanchors] tube testers

[Morris Dillingham]

OF course, you're right it's an emission type. Sorry if I confused anyone
besides myself.  Couldn't remember the name.  (Hope I can remember my own
<g>)  I've a few shorts, myself.


         73 de KI4IUA 
         Morris   


-----Original Message-----
From: boatanchors-bounces at mailman.qth.net
[mailto:boatanchors-bounces at mailman.qth.net] On Behalf Of Al Parker
Sent: Thursday, July 14, 2005 3:16 PM
To: John King; boatanchors at mailman.qth.net
Subject: Re: [Boatanchors] tube testers

Hi JOhn,
    The "bible" on tube testers is "Tube Testers and Classic Electronic
Test Gear" by Alan Douglas (who went to high school with my wife, FWIW).
It's out of print, but is available thru the various usesd book suppliers,
and I'd suggest that you find a copy.  He covers history of various
brands, and most brands' features.
    The B&K's use the basic Hickok circuit, according to him, as did most
mutual conductance (transconductance) units.  (I think Morris Dillingham's
is an emission type, not a mutual conductance, as he describes it.)   They
use basically unfiltered DC, and there's not much, if any, "recapping" to
be done.  Douglas has sections on calibration, accuracy, etc., and is good
reading.  IIRC, there are some precision resistors which can go outta
whack (technical term), but in general calibration isn't particularly
difficult.  Hickok used to supply a "calibrated" 6L6 I think, don't expect
we'd find many of those around, and what good would they be now (R at Re on
ebay).
    Let me know if I can help you by reading more carefully for you.
(how's the wx up there now?)
73,
Al, W8UT
New Bern, NC
BoatAnchors appreciated here
http://www.thecompendium.net/radio/
http://www.hammarlund.info




----- Original Message ----- 
From: "John King" <k5pgw at yahoo.com>
To: <boatanchors at mailman.qth.net>
Sent: Thursday, July 14, 2005 2:36 PM
Subject: [Boatanchors] tube testers


> There has been a recent thread on capacitor checkers
> and the need to recap the instrument to get the power
> supply of the instrument up to specs, voltage wise, to
> give correct test results.
>
> I am curious if the need to rework the power supply of
> vintage tube testers is appropriate as well.
>
> I have a nice "old" B&K tube tester that is supposed
> to be a mutual conductance tube tester. The test
> results are questionable and most of the tubes that
> test weak work as well as the ones with very good
> meter reading. Very few tubes test as "very good".
>
> This makes me wonder what is in the tube tester as a
> power supply to test the tubes with. Seems to me if
> the correct voltages are not provided to the tube
> under test, that the reading would be inaccurate.
>
> Has anyone checked their tube tester power supplies?
> What did you find? Did you find the need to recap the
> power supply, change resistors or bring the power
> supply up to specs?
>
> I would like the benefit of your EXPERIENCE with the
> subject. Please don't ask me "is it plugged in".
>
> I have more than one hundred tube receivers and
> transmitters and believe me, a good tube tester is a
> great help and a bad one is a liability. No one wants
> to throw away good tubes. While substitution may be
> the best test, a tester can give a fast test, if
> reliable. Thanks for your input. You may email direct
> or share your information with the group. All will be
> appreciated. 73, John, K5PGW (since 1958)
>
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