I bought a EICO 635 TUBE TESTER from eBay and find out it can only test the newer tubes (no earlier than 1939). But I have a 1931 Philco 70, 90 radio that use the older tubes. Can I use some kind of adapter with this tester to test the old tube? or, which inexpensive tube testers you recommend can test most of the old radio tubes from 1930-1950? Thanks in advance!

Inexpensive. Knight 600 or Eico 625 both are the same thing. ( Emission only ) Can get old and newer settings chart from BAMA.

There was a link to 'obsolete' tube charts for the EICO 625. This may work for the 635 if controls are similar. I can't remember the link's location as of now, but perhaps someone else on here will recall.

T.

Yes you can make adapters for the old tubes. Use an octal plug or base from a dud. Connect the pins on the 4,5,6,and 7 pin sockets one to one to the octal plug. You can make individual adapters or a single one that uses all four sockets and one plug (all socket "1" pins to pin 1 octal, all socket "2" pins to octal 2, etc). Then use the setup charts for an EICO 625 or Knight 600.

:I bought a EICO 635 TUBE TESTER from eBay and find out it can only test the newer tubes (no earlier than 1939). But I have a 1931 Philco 70, 90 radio that use the older tubes. Can I use some kind of adapter with this tester to test the old tube? or, which inexpensive tube testers you recommend can test most of the old radio tubes from 1930-1950? Thanks in advance!
:

Eico 625 & Knight 600 both are 3 position lever sets. The Eico 635 rotary switch set up. Don't see how to use set up chart from 625 for 635 ?

Whoops. You're right. I was thinking the 635 was like the 628. You can still use adapters but they can't just be one to one. Each adapter needs to be unique. Luckily most of the old types use similar base connections. The settings need to be figured out so as to apply test voltages to the elements. This can be done by looking up the tube to be tested in a tube manual and setting things up for a tube with similar characteristics. Doable but not nearly as simple as hoped.

:Eico 625 & Knight 600 both are 3 position lever sets. The Eico 635 rotary switch set up. Don't see how to use set up chart from 625 for 635 ?
:

Know what your saying about that. Have used an old tube base with stiff wires soldered in the pins. Clip leads to the tube under test. One thing to take note of, is how fast the needle climbs. Gives some indication of a more healthy tube.

Thanks for all the input. If it is too much to modify it, I may just go ahead to sell it on bay again and buy another tester. I saw someone selling a Heathkit IT-3117. It seems it will works with the old tubes as well. Do you recommend it over Knight 600 or Eico 625? Thanks.

:Know what your saying about that. Have used an old tube base with stiff wires soldered in the pins. Clip leads to the tube under test. One thing to take note of, is how fast the needle climbs. Gives some indication of a more healthy tube.
:

:Thanks for all the input. If it is too much to modify it, I may just go ahead to sell it on bay again and buy another tester. I saw someone selling a Heathkit IT-3117. It seems it will works with the old tubes as well. Do you recommend it over Knight 600 or Eico 625? Thanks.
:
::Know what your saying about that. Have used an old tube base with stiff wires soldered in the pins. Clip leads to the tube under test. One thing to take note of, is how fast the needle climbs. Gives some indication of a more healthy tube.
::
:
Terry

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:I went through 2 testers before I finally bought a Precision 912 on eBay. It's a great tester and I haven't found a tube yet that it can't test, from 4 pin to 9 pin, (with an adapter). I love it.
:Terry
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I have the Hickoc 800 & the knight 600. Both tested a 12BE6 as good. (no shorts, no gas) in the radio it had modulation hum. Sub in any other 12BE6. The radio works fine. Even the best so called tube testers have there short comings.

That's why most of us who have been at this for a long time consider tube testers to be our least useful pieces of test gear. Their best use is to determine that a tube is really extremely weak or dead when we don't have another to substitute.

:I have the Hickoc 800 & the knight 600. Both tested a 12BE6 as good. (no shorts, no gas) in the radio it had modulation hum. Sub in any other 12BE6. The radio works fine. Even the best so called tube testers have there short comings.
:

:That's why most of us who have been at this for a long time consider tube testers to be our least useful pieces of test gear. Their best use is to determine that a tube is really extremely weak or dead when we don't have another to substitute.
:
::I have the Hickoc 800 & the knight 600. Both tested a 12BE6 as good. (no shorts, no gas) in the radio it had modulation hum. Sub in any other 12BE6. The radio works fine. Even the best so called tube testers have there short comings.
::
:
T.

When I get an old set I do test the tubes on my Hickok 539 at least to see if any of them are dead or have an obvious short. Low emissions are innocent until proven guilty. I would agree that 90% of problems are with capacitors, shorts, and excrement, and dust. And spiders, because their webs are conductive!

::That's why most of us who have been at this for a long time consider tube testers to be our least useful pieces of test gear. Their best use is to determine that a tube is really extremely weak or dead when we don't have another to substitute.
::
:::I have the Hickoc 800 & the knight 600. Both tested a 12BE6 as good. (no shorts, no gas) in the radio it had modulation hum. Sub in any other 12BE6. The radio works fine. Even the best so called tube testers have there short comings.
:::
::
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:I don't know about that. My 912 has shown inter-element shorts I wouldn't have found otherwise. It tests emission as well as function. Loctal and 9 pin, (with adapter). A bunch of supplement books came with it. I have yet to find a tube it can't test.
:T.
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