[R-390] Tube Testers

[KR4HV]

FWIW, during the early (1970's) part of my long association with and when I
worked for Motorola in their two-way radio division, we still maintained a
LOT of tube sets.  I never went in a Motorola shop and saw a tube tester.
New tubes were always put in the radio under test and testset meter
readings, signal generator settings and other parameters observed to
determine if a tube was operating to spec.  Never, ever was a tube tester
used or even present in the maintenance shops. 

When new I once asked where the tube tester was and I was told that "TV
repair guys" used them because they didn't stock many spares and besides,
testers weren't conclusive.  We always had several new tubes of each type to
try.

IMHO, It's best to spend your money on a set or two of running spares to
have on hand.  Most likely you'll need a few over the years anyway since the
R-300/390A disease is usually severe and generally lasts a long time.

Regards,
Walt
KR4HV

-----Original Message-----
From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]
On Behalf Of KA9EGW
Sent: Tuesday, September 17, 2013 11:29 AM
To: R-390 at mailman.qth.net
Subject: Re: [R-390] Tube Testers

What he said.
73, Brian KA9EGW

-----Original Message-----
From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]
On Behalf Of Glenn Little WB4UIV
Sent: Tuesday, September 17, 2013 1:13 AM
To: R-390 at mailman.qth.net
Subject: Re: [R-390] Tube Testers

Your best tube tester is the instrument that you will be using the tube in.
If it works in the circuit, it is good.
Measure the voltages around the tube.
If they vary significantly from the manual, replace the tube.
If this fixes the problem, the tube was bad.
If the problem remains, put the original tube back in and find the bad
capacitor, open coil or out of tolerance resistor.
Most of the resistors will be out of tolerance, high.
Any paper capacitors should be replaced with mylar or similar capacitors.
By definition, the paper capacitors are bad.




73
Glenn
WB4UIV

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