Tube testers

Discussion in '"Boat Anchor" & Classic Equipment' started by KI7WQH, May 17, 2018.

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  1. KI7WQH

    KI7WQH Ham Member QRZ Page


    I have an FT-101 along with the FL-2100B and the transverters for 6 and 2 meters. With all these tubes I think it might be a good idea to pickup a tube tester but I'm not sure what to look for when browsing around on ebay. Would love some input on what to look for, I don't need anything too fancy, just the ability to check out my current tubes and subsequent replacements I'm going to have to get. Thanks for any help you can lend!

  2. KD0CAC

    KD0CAC Ham Member QRZ Page

    Not necessarily a tube tester expert , more of a tool-jones person , likes fix & repair .
    I did the same thing about 10 yrs. ago , looking for tube testers .
    Part of a bad rap was drug store testers , were set up to sell tubes , or could be ?
    Not that there isn't good tube testers .
    Then have to try to avoid those audio-philes - the guys that made tubes & testers high priced ;) at least thats what I get from other hams .
    One start is to get a list of tubes you would need to test and then look at some suggested tube tester to see if they are in the data / books ,
    its common that a couple of tube tester and many an adapter or 2 to cover most of what you may come across .
    This is because for all the years of tubes & testers , them dang tool guys kept changing things and having one do it all just does not happen , especially with power tubes - the ones in the 2100 , but since you have one of those , most will say the best thing to test them are in the amp / or rig they are meant for - JUST BE CAREFUL and need to do a short test , you do not want to do damage to the amp / or other gear .
    So then trying to find a good working tool that is as old as almost any tester is ?
    Just one of a bunch of good sites to checkout about tube tester is
    Once you have gotten more info on them , then the better the questions get on specific .
    I think a good start is a TV-7 the letters after the 7 are newer abcd .
    KI7WQH likes this.
  3. KA9JLM

    KA9JLM Ham Member QRZ Page

    Normally a tube tester will tell you if a tube is bad, But it may not tell you if a tube is good.

    A in circuit test is the best when dealing with RF.
    AG5CK, KM1H, KI7WQH and 1 other person like this.
  4. KE4OH

    KE4OH Ham Member QRZ Page

    ^^^^^^^ This ^^^^^^

    So, there are two main kinds of tube testers: 1) Emission testers and 2) transconductance testers.

    Type 1 is very common and inexpensive. And very limited. I do have one because I deal with a jillion different types of tubes over time and I got it cheap. It's good for a quick check that the tube doesn't have shorted elements and has at least some cathode emissions. It sometimes gives me a clue that a tube might be gassy. It doesn't tell me how much transconductance the tube has nor what plate/screen current it draws at a given voltage. I can't use it to "match" multiple tubes into groups with similar operating characteristics.

    Type 2 is harder to come by and costs a lot more. But it will do all the things I mentioned that Type 1 will not do.

    No tube tester can tell me that a given tube will or will not work in a given circuit. Tubes that test bad may still work in some circuits.

    Your FT-101 has 3 tubes in it. A driver tube and two sweep tubes. If your rig still tunes up correctly and puts out reasonable power, your tubes are good. A lot of testers out there won't have control settings / results published for a lot of sweep tubes. (They can be derived, however.) Your rig is the best tube tester.

    Your FL-2100B has 2 x 572B tubes in it. Again, if it tunes up correctly and puts out reasonable power, your tubes are good. Also, I'm not aware of any commercial tube testers commonly made back in the day that will test these tubes. Tube manufacturers and good tube dealers will have built their own test rigs for high-power tubes like these.

    I don't know what tubes, if any, are in the transverters, so no comment on those.

    But, don't run out and buy a tube tester just for what you have. You really don't need it and most of them don't do a good job anyway. The emission testers (that I called "Type 1" above) were and are just quick and dirty devices that service guys could use to quickly find tubes that *might* be suspect. That made it easy and fast to pick the low-hanging fruit and also to sell the customer more tubes. Nearly all emission testers have a big meter on the front that has a big red arc that reads "BAD". "Look Mr. Jones - This tube is bad! I'll replace that for sure and keep looking for the other problems". Ka-ching! Then the possibly bad tube then goes back into the repair guy's case where it might eventually find itself installed in some other radio/TV/stereo ...
    AC0OB, KI7WQH and K7TRF like this.
  5. K7TRF

    K7TRF Premium Subscriber QRZ Page

    The posts above are dead on, the best way to test RF tubes is in the rigs themselves. Unless you're going to build or buy a whole lot of tube gear that uses a wide variety of tubes you'd probably be better off just picking up another working FT-101 to test tubes independently from your existing rig instead of something like a Hickock tube tester.
    KI7WQH likes this.
  6. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    The best tube tester, in the world, is the unit itself! I do have several tube testers but I seldom use one of those.

    Here are 3 of those tube testers:

    I have, numerous times, run into tubes that test good will not work in a unit and tubes that test bad that work fine!

    In the 1950s, General Electric actually built a tube tester that could really test tubes in virtually every situation. That tube tester cost right at $3,000,000 back in that time frame.

    I am fortunate in that I do have a fairly good supply of replacement tubes:

    Glen, K9STH
    KI7WQH likes this.
  7. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    KD2ACO and KI7WQH like this.
  8. KI7WQH

    KI7WQH Ham Member QRZ Page

    Thanks for all the replies! Looks like I have some reading to do
  9. KD2ACO

    KD2ACO Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    There's a DynaJet in the selling pages here. These are really nice if you're willing to spend a bit.

    I'm constantly serious with tubes. There's a TV7-D/U on my bench to plow through piles of them to weed out bad ones and wake up cathodes on rare and expensive oldies but goodies.

    After that, a curve tracer gives you a clue to what's going on... but that's over the top for most folks unless you make a living with the device.


    All of the goodies only go so far, so as mentioned above, you need to test tubes out in the device that's going to use them, especially at RF and high voltage... but,

    Toyz R us! :p

    If you have only a few devices with tubes, you can get by just fine by substitution and call it good.
    Last edited: May 18, 2018
  10. AJ4CU

    AJ4CU Ham Member QRZ Page

    When all else fails get a Hickok 539C, just recently went through recapping and replacing a few carbon comp resistors then a calibration on mine and it is in fine condition.

    One of the better testers out there.

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