03-29-2016, 09:51 AM
I have to agree with Mike. A tube tester will give you a good idea of the condition of a tube, shorts, emission gM and such. But the real test is in the circuit. Oft a tube will not work in one circuit, even though it tests perfect on the tester, yet work fine in another. With most types of tubes we use no longer being produced, don't toss anything that may read weak, only if it is shorted, dead or verified gassy. Output tubes are least sensitive, and if you don't want room shaking bass, a weak tube can serve for years. Been using a weak 47 in the old 70 for years. Sounds fine so far.
I have had a few experiences with tube testers, but by no means a pro at it. I have both a Hickok 600a, and Precise 111. They don't read the same. I tried once to calibrate the 111 to match the 600a. Didn't work. They simply read different. The values are on the charts. If I recall, the 600a read higher than the 111. Calibration seemed ok on the 600a, and I had painstakingly calibrated the Precise. Same NOS tubes checked accurately on both according to each ones tube chart. The RCA tube manual can give you fits to when you are looking at the gM of a tube. Seldom will the tube being tested match the RCA manual, even when new. Something else that comes to mind is the variations in line voltage. I cant accurately test a tube on the 600a when my wife is cooking supper on our electric stove. Each time an element cycles, the reading on the tube tester also changes!
As Mike mentioned, you don't need a laboratory tube tester for bench radio work. Even a simple emissions tester will give you an idea of the condition of a tube and check for shorts. They don't put a load on the tube like the gM testers tho. I prefer the 600a over the 111, mainly for the ease of setup, but if I really want to test a tube, check for noise, heater current or halfway match tubes, then I go to the Precise 111. Mine does have solid state rectifier for the 83. I have also read up on the bogey tube. It really isn't a bad idea to have one, whether it is one you made or from some supplier. It gives you a quick reference to check your calibration, but there are other ways to calibrate the 600a, which is how I checked mine, and left it alone.
I have had a few experiences with tube testers, but by no means a pro at it. I have both a Hickok 600a, and Precise 111. They don't read the same. I tried once to calibrate the 111 to match the 600a. Didn't work. They simply read different. The values are on the charts. If I recall, the 600a read higher than the 111. Calibration seemed ok on the 600a, and I had painstakingly calibrated the Precise. Same NOS tubes checked accurately on both according to each ones tube chart. The RCA tube manual can give you fits to when you are looking at the gM of a tube. Seldom will the tube being tested match the RCA manual, even when new. Something else that comes to mind is the variations in line voltage. I cant accurately test a tube on the 600a when my wife is cooking supper on our electric stove. Each time an element cycles, the reading on the tube tester also changes!
As Mike mentioned, you don't need a laboratory tube tester for bench radio work. Even a simple emissions tester will give you an idea of the condition of a tube and check for shorts. They don't put a load on the tube like the gM testers tho. I prefer the 600a over the 111, mainly for the ease of setup, but if I really want to test a tube, check for noise, heater current or halfway match tubes, then I go to the Precise 111. Mine does have solid state rectifier for the 83. I have also read up on the bogey tube. It really isn't a bad idea to have one, whether it is one you made or from some supplier. It gives you a quick reference to check your calibration, but there are other ways to calibrate the 600a, which is how I checked mine, and left it alone.
If I could find the place called "Somewhere", I could find "Anything"
Tim
Jesus cried out and said, "Whoever believes in me , believes not in me but in him who sent me" John 12:44
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