Out of the thousands of tubes I have tested, it was a rare occasion I had to go into the circuit to find a bad tube. So unusual I cant remember the last time that happened with me. Very rare!
Lou WA5LOU
On Fri, Jan 19, 2024 at 10:51 PM Jim Shorney <jimNU0C@gmail.com> wrote:
Nevertheless, it remains a fact that a tube can be "good" on a tube tester and fail in circuit, and vise-versa. That is why it is said that the best test of a tube is the circuit that you want it to work in.
73
-Jim
NU0C
On Fri, 19 Jan 2024 22:19:09 -0500
"Lou WA5LOU" <loueverettsr@gmail.com> wrote:
> I've relied on mine for years and years and it has never failed me! I
> could not work on Tube rigs speedily without it!
>
> Lou WA5LOU
>
> On Fri, Jan 19, 2024 at 10:12 PM Don Root VA3DRL <
> drootofallevil@teksavvy.com> wrote:
>
> > Robert and all
> >
> > Re "I am no expert but I believe you can't rely too heavily on any tube
> > tester. "
> >
> >
> >
> > Well if it "reads bad" it likely *is bad. *
> >
> > if it "reads good" it may well be * good *under the condition it is
> > being tested at*. *
> >
> > Most TTs measure Gm [where amplification is part of the intent in the
> > tube.]
> >
> > If you have a variable Mu tube you really want to know if it works
> > properly with a small bias. But you want it to also work properly at a
> > large negative bias
> >
> > .. if you don't test it down there you might not know it has too hi a gm
> > .. maybe that is where the gas messes things up like Jacques said.
> >
> > I recently saw other postings somewhere the front end tube tested ok …
> > but did similar things
> >
> > .. but we need to get the books out on the details
> >
> >
> >
> >
> >
> >
> >
> > *From:* Amateur-repairs@groups.io [mailto:Amateur-repairs@groups.io] *On
> > Behalf Of *Gary WB6OGD
> > *Sent:* Friday, January 19, 2024 11:58 AM
> > *To:* Amateur-repairs@groups.io
> > *Subject:* Re: [Amateur-repairs] Creating a LSB and USB Test Signal!!
> >
> >
> >
> > Robert,
> > Good advice.
> > I am no expert but I believe you can't rely too heavily on any tube
> > tester. The actual circuit where the tube goes is the best tester.
> >
> > I downloaded the 51s1 manual just to have a look. The BFO is one tube. I
> > would try another, there are probably many types that could substitute
> > there if you don't have a good spare. I am thinking it maybe has a
> > filament to cathode short or leakage of some kind that lets the AC filament
> > signal onto
> > the BFO signal. But just a guess.
> > 73,
> > Gary
> > WB6OGD
> >
> >
> > --
> > 73 don va3drl
> >
> >
> >
>
>
>
>
>
--
73
-Jim
NU0C
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