[R-390] Tube testers

[Tracy Fort]

Guess I=92m a wimp!

-----Original Message-----
From: r-390-bounces at mailman.qth.net =
[mailto:r-390-bounces at mailman.qth.net]
On Behalf Of Bernard nicholson=20
Sent: Tuesday, June 26, 2007 8:39 AM
To: r-390 at mailman.qth.net
Subject: [R-390] Tube testers

Guys tube testers are for wimps  the best tube tester is the circuit =
that
the tube is working in , you can check the voltage drops across
plate&screen& cathode resistors and with a modicum of mental arithmetic
[remember that?] you can easily see what is happening in a circuit, in a
well designed radio tubes don't work very hard at all !  The original =
signal
Corps Specs for the RCA  AR88  calls for the set to perform to its
specification with ANY or  ALL tubes at 30% emission   This is the =
reality !
this is the reason that tubes are rejected on the tester but the set is
still working OK,  I was trained in communications in Carrier Telephony  =
,
we used to keep detailed maintenance logs of every piece of equipment =
And
performance checks were done regularly this gear used literally =
thousands of
tubes  and many tubes were only changed after many years when the specs =
were
no longer achieved, Back in these times  people who resorted to tube =
testers
were called Valve or Tube Jockeys,  They were looked down upon and were
figures of fun .   Tube testers were used in Australia as a marketing =
tool ,
you could take all the tubes from your radio or TV and test them in the =
shop
where they could sell you some more, Very convenient !   Surely if we =
have
Pretensions to own and Maintain an Esoteric R390A  one can learn about
mutual conductance and amplification factor Ect   then all you need is a
voltmeter Regards to everyone  and keep the posts coming .=20
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