After retiring from the computer maintenance field, I am going to
start repairing some old Tube radios my father in law left unfinished
when he past away. From way back when school I got my electronics
degree from; it was stated that good in circuit diagnostics was just
as good as using a tube tester (if you were good at repair).

Is this s true-ism or does one need a tester? Most of radios are 30,
40's. A few AK's, but testers didn't go back that far to some of
their tubes. Thanks for your time and efforts.

Don

"don" wrote in message
...
After retiring from the computer maintenance field, I am going to
start repairing some old Tube radios my father in law left unfinished
when he past away. From way back when school I got my electronics
degree from; it was stated that good in circuit diagnostics was just
as good as using a tube tester (if you were good at repair).

Is this s true-ism or does one need a tester? Most of radios are 30,
40's. A few AK's, but testers didn't go back that far to some of
their tubes. Thanks for your time and efforts.

Don


one could say the best test for either tune or transister is "in circuit"
..... but having a known working tester, meter, curve tracer, or test jig
sure comes in handy.

Hi,

A few AK's, but testers didn't go back that far to some of
their tubes.

Actually they do, depending how complete a test you need. You can
pick up a 1950s Heathkit or something similar, with test data for
tubes back to the 1920s. Try poking around in the "test equipment"
section of the Forum at antiqueradios.com; your question comes up
every so often there, and you'll also find lots of pther people who
restore older radios.

Alan

"don" wrote in message
...
After retiring from the computer maintenance field, I am going to
start repairing some old Tube radios my father in law left unfinished
when he past away. From way back when school I got my electronics
degree from; it was stated that good in circuit diagnostics was just
as good as using a tube tester (if you were good at repair).

Is this s true-ism or does one need a tester? Most of radios are 30,
40's. A few AK's, but testers didn't go back that far to some of
their tubes. Thanks for your time and efforts.

Don

Most of the tube circuits are seperated from each other by capacitors so the
DC voltages don't usually interact from one stage to another. That makes it
easy to measuer the DC voltages and see what is going on in each stage. I
found it easier to just pop in a tube instead of fooling with the tube
tester. With the tubes becomming harder to come by and at the prices, a
tester may come in handy.

They did make testers that would check about any of the receiving tubes of
any year. At one time I had 2 testers , one went way back to the older
tubes. There are also several diffearnt kinds of testers. I think one was
an emission tester and not very good , the better one was a mutual
conductance tester. It set the tube to a nominal set of operating
conditions and compaired the meter reading to a "standard tube"chart and
the meter read out the percentage it compaired to it.

In article ,
Alan Douglas adouglasatgis.net wrote:

Hi,

A few AK's, but testers didn't go back that far to some of
their tubes.

Actually they do, depending how complete a test you need. You can
pick up a 1950s Heathkit or something similar, with test data for
tubes back to the 1920s. Try poking around in the "test equipment"
section of the Forum at antiqueradios.com; your question comes up
every so often there, and you'll also find lots of pther people who
restore older radios.

Alan

I sold my old Sencore tube tester on eBay several months ago. I think I
got about $50 for it. There were several others available then and I
imagine there are now, though I haven't looked recently.

"don" wrote in message
...
After retiring from the computer maintenance field, I am going to
start repairing some old Tube radios my father in law left unfinished
when he past away. From way back when school I got my electronics
degree from; it was stated that good in circuit diagnostics was just
as good as using a tube tester (if you were good at repair).

Is this s true-ism or does one need a tester? Most of radios are 30,
40's. A few AK's, but testers didn't go back that far to some of
their tubes. Thanks for your time and efforts.

Truism (in the absolute sense), no. Generally speaking, yes. In-circuit
testing can quickly lead to the identification of a single fault in
non-feedback circuits. The problem is, of course, there are circuits with
multiple faults and circuits that use feedback (very little of that in the
30s and 40s in non-oscillators; luckily for you).

A tube tester will have to be verified ... don't forget that important point
as you are talking about OLD stuff. OLD test equipment is going to be a big
question mark.

If I were in your shoes, I'd first try to find a source of parts. If you
suspect a tube, having a known good one to plug in is hard to beat.

Have fun and good luck.

Charles Schuler wrote:
"don" wrote in message
...

After retiring from the computer maintenance field, I am going to
start repairing some old Tube radios my father in law left unfinished
when he past away. From way back when school I got my electronics
degree from; it was stated that good in circuit diagnostics was just
as good as using a tube tester (if you were good at repair).

Is this s true-ism or does one need a tester? Most of radios are 30,
40's. A few AK's, but testers didn't go back that far to some of
their tubes. Thanks for your time and efforts.


Truism (in the absolute sense), no. Generally speaking, yes. In-circuit
testing can quickly lead to the identification of a single fault in
non-feedback circuits. The problem is, of course, there are circuits with
multiple faults and circuits that use feedback (very little of that in the
30s and 40s in non-oscillators; luckily for you).

A tube tester will have to be verified ... don't forget that important point
as you are talking about OLD stuff. OLD test equipment is going to be a big
question mark.

If I were in your shoes, I'd first try to find a source of parts. If you
suspect a tube, having a known good one to plug in is hard to beat.

Have fun and good luck.





While tubes in general are generally ok in my experience, that's still
the first thing to test when you open up an old radio. The next step is
to replace every electrolytic capacitor in the set, and if you take your
time you can even stuff new caps in the old casings to keep the original
look. Clean all the switches with a shot of contact cleaner and give
everything a good visual check. Once that's been done then power the set
up with no tubes installed and check for reasonable voltages from the
power transformer if present, then reinstall the tubes and go from there.

If you omit any of these steps you'll be chasing your tail trying to
track down a problem which may just be a multitude of tired old components.

If you omit any of these steps you'll be chasing your tail trying to
track down a problem which may just be a multitude of tired old
components.

Indeed, that (tired old components) is the reason why I have little interest
in restoring vintage electronics. I love the look, but don't need to hear
or see it play.

Charles Schuler wrote:
If you omit any of these steps you'll be chasing your tail trying to
track down a problem which may just be a multitude of tired old
components.


Indeed, that (tired old components) is the reason why I have little interest
in restoring vintage electronics. I love the look, but don't need to hear
or see it play.




I always figured if it can't be made to work then it's not worth keeping
around, but to each their own I suppose. Restoring an antique radio can
be a fun challenge, and is certainly a lot less work than restoring an
old car.

On Fri, 06 Jan 2006 23:08:03 -0800, don
wrote:

After retiring from the computer maintenance field, I am going to
start repairing some old Tube radios my father in law left unfinished
when he past away. From way back when school I got my electronics
degree from; it was stated that good in circuit diagnostics was just
as good as using a tube tester (if you were good at repair).

Is this s true-ism or does one need a tester? Most of radios are 30,
40's. A few AK's, but testers didn't go back that far to some of
their tubes. Thanks for your time and efforts.

Don

I recall my old teacher saying you need to use a GOOD tube tester. A
cheap one is a waste of time. I'm sorry I forget the details, but I
suspect it's something like the transconductance models someone else
mentioned. My teacher was of the opinion there were very few worth
using. I'd imagine he was qualifying this by what was reasonably
priced for techs.

wrote in message
...
On Fri, 06 Jan 2006 23:08:03 -0800, don
wrote:

After retiring from the computer maintenance field, I am going to
start repairing some old Tube radios my father in law left unfinished
when he past away. From way back when school I got my electronics
degree from; it was stated that good in circuit diagnostics was just
as good as using a tube tester (if you were good at repair).

Is this s true-ism or does one need a tester? Most of radios are 30,
40's. A few AK's, but testers didn't go back that far to some of
their tubes. Thanks for your time and efforts.

Don

I recall my old teacher saying you need to use a GOOD tube tester. A
cheap one is a waste of time. I'm sorry I forget the details, but I
suspect it's something like the transconductance models someone else
mentioned. My teacher was of the opinion there were very few worth
using. I'd imagine he was qualifying this by what was reasonably
priced for techs.



maybe his theory is that a tube has many more parameters then a tester with
a single meter and a few switches can account for. like checking a
transistor with an ohmmeter: you know its good or bad but not how good.

for ease and safety the tester beats probing HV terminals with a meter or
scope probe.

"TimPerry" wrote in message
...

maybe his theory is that a tube has many more parameters then a tester
with
a single meter and a few switches can account for. like checking a
transistor with an ohmmeter: you know its good or bad but not how good.

for ease and safety the tester beats probing HV terminals with a meter or
scope probe.


As with many testers you have to know what to look for. Most are not a
simple go/nogo tester. Some tubes can test good in a fairly good tester and
still be bad or atleast not work in a circuit. I have used a tester and cut
the filiment voltage back on a 'good' tube and watch the meter fall off to
the 'bad' section of the meter. The tube will work in some circutis but not
others as it can not substain higher plate current if needed. Most tubes
will fall off some and you have to know about how fast they will fall to
really be good. Back in the days when alalog meters were used you had to
know that the meter could load down a circuit and the voltage may not show
what you expect in the high resistance tube circuits.