Tube Tester?

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,

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

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.

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

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.

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.

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.

with

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.