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    Tube Tester

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    Ernstmach

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    Tube Tester

    Post by Ernstmach on Tue Jul 18, 2017 8:25 pm

    Hey Everyone!
    I'm looking for a tube tester. Lots of them for sale out there on the interweb.
    Anyone have a preference?
    I will probably use it occasionally but would like to pick up a good unit.
    Hickok seems to be a favorite... What do you think/use/prefer?
    Thank you very much!


    I did do a search but it didn't turn up much.
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    j beede

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    Re: Tube Tester

    Post by j beede on Wed Jul 19, 2017 1:07 am

    A few observations regarding tube testing... What do you plan to do with a tube tester? "Test tubes" I suppose is the obvious answer. Oddly enough most testers don't do much of a test. Consider:

    -An emissions tester will enthusiastically report a tube as "good" or "bad". I'll gladly take your "bad" Mullard, Telefunken, and Amperex dual triodes tubes as they usually sound great in my preamp--in spite of Mr. Hickok and Mr. B&K showing a needle in the "bad" zone.

    -Tube matching for push-pull applications is not a bad idea. If you want to match octals you probably already have a decent tube tester for matching them--a Dynaco MkIII or Stereo 70 will do. The process is tedious but effective. A MaxiMatcher will speed things up if expediency is a priority.

    -Most any old school tester will do an adequate job of testing for pin-to-pin shorts. If you are prone to inserting apocryphal tubes in your amplifier(s) this sort of pre-testing may make sense.

    -If you want to test tubes to see if they will make your amp sound warmer, less tubey, more tubey, brighter, fuller, or richer... Neither Hickok, nor Eico, Nor B, nor K can tell you that. No substitute for quality seat time here.

    -The collectible tube resellers I know tend to have a variety of testers as some tubes perform better on one platform versus another.

    If you have already made up your mind that a tester is in the cards for you... I would suggest you buy a cheap emissions tester that tests for pin shorts ($20-80 on Craigslist) or a new MaxiMatcher--but only if you plan to match octals or 9-pin dual triodes, not both.

    If you are considering the Amplitrex tester then you have probably (and appropriately) disregarded this reply by now.

    If you are buying a tester as an investment, e.g. in place of a 401K, you may be too late... Prices on Hickok 539 and TV-7s are high already. Can they go any higher? The MaxiMatcher is starting to look like a bargain.

    Good luck!
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    peterh

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    Re: Tube Tester

    Post by peterh on Wed Jul 19, 2017 1:53 am

    Amen
    j beede really nailed it!
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    Peter W.

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    Re: Tube Tester

    Post by Peter W. on Wed Jul 19, 2017 8:05 am

    Mpfffff.... Tube Testers. Mpffffff.........

    OK - this is from an old post in another venue, and mostly focused on vintage radios, but applicable here:

    Basic stuff with a lot of generalizations and special-nature stuff
    excepted:

    Tube testers overall come in two groups: Emissions Testers and GM/MC
    (Mutual Conductance) testers.

    Emissions Testers: The much-simpler of the two types, these measure the
    "Edison Effect", whether there is any electron flow between cathode and
    anode. As this is the least any tube must do in order to work at all,
    the accuracy of this single measurement is limited as to the actual
    performance-in-place of the tube. IN 99-44/100ths% OF ALL APPLICATIONS,
    AN EMISSIONS TESTER CAPABLE OF "SHORTS" AND "GAS" TESTS will be more
    than adequate for all vintage radio work. See below on Shorts and Gas.

    GM/MC testers: These tester types measure 'gain' on a tube against a
    scale centered on the 'average' gain required for such tubes, and under
    specific parameters including bias((usually) negative voltage applied
    to the grid). Emissions is assumed or there would be no gain, so these
    testers give a far more meaningful picture of tube performance under
    actual operating conditions. IF YOU WILL BE DOING EXTENSIVE AUDIO WORK
    OR FEEL THE IRRATIONAL NEED TO MATCH TUBES, then a GM-type tester is a
    necessity. See "Other measurements" below.

    Other measurements:

    Shorts: No tube tester should be considered under any conditions that
    does not have specific and panel-marked settings to test for Shorts.
    Some shorts will not show up with a cold tube, so a simple VOM will not
    show all of them. Repeat: If a tester does not have clear, specific
    "SHORTS" testing procedures, reject it.

    Gas: Some tubes become gassy over time or are gassy... either from
    leakage through the pins, poor manufacturing, a bad 'getter' or
    similar. gassy tubes can wreak havoc due to high-voltage 'leaks' and
    other problems. Testers should have a way to detect gassy tubes, also
    clear and specific. Reject any that do not. Note that these tests may
    be complex, but they must be there.

    Life: Smoke and mirrors for the most part. Drop the filament voltage by
    one setting or reduce the line-in voltage by 25% or so, you will get
    the same results on the meter. But a nice addition if everything else
    is there first.

    Other Measurements: Some testers will measure or allow to  be measured
    Plate and/or Filament currents. Some will allow the addition of an
    external bias resistor. These are necessary if "matching" is to be
    done, but not relevant much to vintage radios.

    Limitations: Not all testers do a great job of measuring high-demand
    tubes such as a 6550 amplifier tube or an 83 mercury rectifier tube.
    The typical vintage radio person will seldom see either.

    So why have a tube tester in the first place?

    Mpffffff..... well..... they can be nifty things to show off, all those
    sockets, settings, knobs and other mad-scientist aparatus. But the
    brute fact of the matter is that in most cases the best test of any
    tube is the gear it is in. All that aside:

    - they are useful for go/no go decisions, based on intact filaments,
    shorts and gas.
    - they will allow you to screen tubes before installation or detect bad
    tubes prior to troubleshooting.
    - under some conditions, they will indicate potentially bad tubes or
    point towards potential failures due to bad tubes.
    - if one does extensive audio work, or works with expensive or rare
    tubes or chooses to match tubes or has any of several other unusual
    requirements, then an MC tester will be required. This is the
    56/100ths% crowd.

    So, to sum up (and a lot of my *opinion* sneaks into this):

    Tube testers are largely luxuries as instruments, to be purchased
    _AFTER_ a good isolation transformer, a properly metered Variac, a very
    good VOM, a good signal generator, even after a good signal tracer.
    Equal to a full-voltage cap tester, but before an Oscilloscope, just.

    A tube tester *MUST* have clear, specific tests for shorts and gas.
    Harp, harp, harp. Without them, it is useless for any practical
    purposes.

    Brands:
    Sencore, Heath and Simpson make some very nice emissions-type testers
    with all the required tests as noted above. Others do as well, but
    sometimes the brand-names are just better, easier to use and better
    supported. The three named above are extremely well-supported,
    up-to-date charts are readily available and they are fairly robust.

    Hickok, Stark, Eico, Heath, Supreme, Simpson, AVO and others make MC
    testers. Hickok is considered to be the TOL, with specific reference to
    the 539C. In point of fact, the good 'names' all make good testers, but
    Hickok has the best support-in-detail and reputation. AVO if you are in
    Europe.

    Thing to keep in mind: There was a point when every back-street
    instrument maker was making tube testers for home use. And even some of
    the better 'names' chose to cash in on the post-war consumer
    electronics craze. A great deal of crap got out into the market and
    resurfaces every day. Unless you know what you are doing, DO NOT
    purchase a tester sight-unseen, especially from an unknown or untrusted
    source. Period.


    I keep a properly calibrated Hickok 539B and a very nice Simpson emissions tester. The former has become increasingly useful as I shift from 95% vintage radio stuff to about 50:50 radio/audio as of late. With additional instrumentation (two VOMs) I can now match tubes very closely, and, yes, it will drive a 6550. The Simpson handles the vast bulk of my radio needs as - and I repeat - the best test of any tube (other than shorts and gas) is the radio needing it.

    Were I looking for a tube tester today, would I drop the probably necessary $1,200 - $1,500 for a properly calibrated and reliable Hickok 539-series? Not likely.

    Of course, now that I have these beasts, and it has gotten out into the 'community', I average about a visit per month from those needing tubes to be tested. And there is usually a line at Kutztown.

    http://tone-lizard.com/tube-testers/
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    Ernstmach

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    Re: Tube Tester

    Post by Ernstmach on Wed Jul 19, 2017 9:24 am

    Thanks for all of the information everyone.


    I do have an Accurate Instruments Co Model 257 emissions tester.
    Had I done a bit of "due diligence" I would have found that it is not one of the better pieces of equipment.


    Do I need a tester?
    No but I would like to have the ability to test vintage tubes, tube matching and so on.
    I'm also interested in the learning aspect.

    Big Harry

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    Re: Tube Tester

    Post by Big Harry on Wed Jul 19, 2017 9:40 am

    Picking the best tester depends on what you want it to do and how much you want to spend. I own several testers and they all get used. The Hickok testers are well regarded and I own a 539B and 600A which I use regularly. I also own BK 707 and 747 testers and the 707 is the tester that gets used most often as it is the easiest to set up. Companies such as Jackson, Heathkit, Eico also made good testers and are usually a bunch cheaper than anything made by Hickok. There is a website called Tone lizard that has a good article on the different tube testers and what they can do.
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    Ernstmach

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    Re: Tube Tester

    Post by Ernstmach on Wed Jul 19, 2017 9:47 am

    Hey Big,
    Looking at what is out there most are pricey.
    Not sure yet what my upper limit would be. If I'm going to spend the money I want to be sure it's worth it.
    Thanks for the link! I'll get over to it and check it out.

    I should add that a tester would be nice to keep my guitar amps working well.
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    Peter W.

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    Re: Tube Tester

    Post by Peter W. on Wed Jul 19, 2017 9:59 am

    If you want to match, and do not want to shell out for a modern-production tester ($2,500 and up) that ties into your computer for nice curves and such, you have two (2) choices:

    a) The Hickok 539 series and the Stark/WE clones of same.

    b) AVO Mk3 or Mk4.

    All others will need to be modified (there are some nifty mods to some Jackson units). And the Hickok TV7 series *WILL NOT* do it, despite rumors to the contrary.
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    Ernstmach

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    Re: Tube Tester

    Post by Ernstmach on Wed Jul 19, 2017 10:03 am

    Thanks for that info.
    Reading the article on Tone Lizard about testers is quite enlightening..
    Rethinking this whole thing. Will keep looking into it though.
    Thanks!
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    peterh

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    Re: Tube Tester

    Post by peterh on Wed Jul 19, 2017 11:07 am

    Some readings from "jac" who has opinions about tube-testers :
    http://www.jacmusic.com/Tube-testers/
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    Peter W.

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    Re: Tube Tester

    Post by Peter W. on Wed Jul 19, 2017 11:29 am

    To the OP - look for the MARC meet, usually around Lansing - you just missed this year as it finished on 7/15. But, you will find any number of testers there and will be able to kick the tires as well. Should you go next year, I will give you a couple of names to make sure you get to the right information.

    If you ever get east, the Kutztown Radio Show (September) is another excellent source where tires may be kicked and testers may be actually tested in direct comparison to fully calibrated units (mine) at the Club table - where I run a clinic for the entire show. At the spring show, there were three (3) Hickok 539-series testers, two sold in excess of $1,200 each in pristine and fully calibrated condition.

    Now, after some thought - I will render a few opinions on the species as a whole, and their general utility. A tiny bit of history:

    I started in this hobby over 40 years ago assembling a number of Dynaco SS products - some of which I still have to this day. And got into tube via a gift of a Philco table radio in rough shape from my future brother-in-law. As time went on and the hobby progressed from filling the need for a decent stereo into a collection of radios, then some tooling, spare parts, and so forth, I started frequenting a vintage electronics warehouse in north Philadelphia - Leon Fertik owned and ran it with his wife. Fast-forward 15 years. Leon's lovely wife died. He got tired of dealing with a 15,000 s.f. unheated warehouse full of *stuff* that he purchased, sorted, collated, packed and more, now all by himself. So, he decided to sell out. Did I mention he had 30,000 tubes? Mostly TV, but quite a number of 'good' ones as well. And two Hickok testers. He and I got along well - I helped him lift and carry sometimes, and also did some fine soldering work for him - his eyes were weak at close range. So, he offered me my pick of the two testers, $100 flat. One of them was a GE-origin device, complete with calibration tubes, obsolete/Euro/Military/WE testing literature, a spare roll, and its log-book (came from GE Re-Entry Systems Division AKA Warheads). The other did not. I took the one with the 'paper'. That is my 539B. No, it is not radioactive - and yes, I do have a Geiger counter (my wife once collected Fiesta Ware). That was in 1997. I replaced the 83 with a solid-state device, double-checked the calibration, cleaned the innards and it has served me flawlessly since. I have come to appreciate its capacities and it will be taken from my cold, dead fingers if my son-in-law does not get it first. The Simpson 555 was a $10 garage-sale item purchased at about the same time, cleaned and checked. For most of my radio work, it is adequate - not to mention very easy to use.

    So my advice is to think long and hard before *Investing* in a tube tester. At this moment, I have, audio and radio, about 34 active devices that are tube-based. I have, probably, upwards of 3,000 tubes stored specific to those devices. Having a couple of testers around is likely justified. As I lurch towards retirement and becoming more active directly in the hobby, I will be using these devices yet more for culling the herd considerably both in livestock and feed.

    Were I to have half-a-dozen devices and use them not-so-much, having a tester would be less desirable. Were I working very nearly only with post-blight tubes, probably less so. And not at $1,200 for a reliable specimen.


    Last edited by Peter W. on Wed Jul 19, 2017 5:32 pm; edited 1 time in total (Reason for editing : More blather.)
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    deepee99

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    Re: Tube Tester

    Post by deepee99 on Wed Jul 19, 2017 8:07 pm

    HAWWRRR
    The only thing better than owning a Hickock is having a best friend who does. Kinda like wooden boats.
    I blew up my best friend's 539 with a shorted 6550 a year ago and albeit he only lives a block away, doesn't return my calls anymore.
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    Ernstmach

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    Re: Tube Tester

    Post by Ernstmach on Wed Jul 19, 2017 9:18 pm

    Looks like I'll be going to Great Lakes HamCon .:http://glhamcon.org/
    Less than 15 miles from my house. I'll take some cash and look for one 0f the testers mentioned here.
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    tubes4hifi
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    Re: Tube Tester

    Post by tubes4hifi on Thu Jul 20, 2017 11:46 am

    the best instrument for matching OUTPUT tubes is a push-pull tube amp, such as ST70 or ST120.
    Set the bias the same for each tube and then read the differences in cathode current (bias reading).
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    deepee99

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    Re: Tube Tester

    Post by deepee99 on Thu Jul 20, 2017 11:57 am

    tubes4hifi wrote:the best instrument for matching OUTPUT tubes is a push-pull tube amp, such as ST70 or ST120.
    Set the bias the same for each tube and then read the differences in cathode current (bias reading).
    Roy, not to sound thick here, but do you mean, set the pots in exactly the same position, then dive in with the Fluke?
    I understand that even best tube-testers don't put output tubes in "real world" stress conditions.
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    Ernstmach

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    Re: Tube Tester

    Post by Ernstmach on Thu Jul 20, 2017 4:37 pm

    "
    the best instrument for matching OUTPUT tubes is a push-pull tube amp, such as ST70 or ST120.
    Set the bias the same for each tube and then read the differences in cathode current (bias reading)."

    Any chance I could use one of my MkIII's?

    As always, lot's of great advice here!
    Thanks fella's!
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    peterh

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    Re: Tube Tester

    Post by peterh on Thu Jul 20, 2017 4:51 pm

    Ernstmach wrote:"
    the best instrument for matching OUTPUT tubes is a push-pull tube amp, such as ST70 or ST120.
    Set the bias the same for each tube and then read the differences in cathode current (bias reading)."

    Any chance I could use one of my MkIII's?

    As always, lot's of great advice here!
    Thanks fella's!

    Yes, but you have to modify the Mk-III to have individual cathode resistors.
    As original there is a 11.2 ohm resistor shared between the cathodes ( pin 8 )
    Replace this with 2 10 ohm resistors ( 0.5w is ok) between pin 8 and ground on
    both kt88 sockets.
    Then identify the "biaset" cable on the external octal plug ( pin 8), make this connect
    to one of the kt88 (pin8 ). Connect the other kt88(pin 8 ) to pin 7 on the external
    octal connector. This connection will be measuring points for cathode current, one for
    each tube. The voltage between (7,8) and ground represents the current each tube
    draws where +.5V equals 50mA current.

    Mount your tubes, turn on and measure the voltage at the measure points, using 2
    multimeters is an advantage. Adjust with the bias adjustment pot. A perfectly
    matched tube-pair will have same reading on pin (7,8) , any differences here
    marks unbalanced tubes.
    To measure a lot of tubes, adjust the bias pot to 0.5V with a pair of good tubes,
    then without altering the pot install tubes , let them warm up and note the
    voltage at (7,8) and mark the corresponding tube with the current.
    When the lot of tubes are measured, start pairing tubes with simular current markings.

    Always have a load on the amp. If not speakers use a 8 ohm power resistor.
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    j beede

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    Re: Tube Tester

    Post by j beede on Thu Jul 20, 2017 5:49 pm

    j beede wrote:A few observations regarding tube testing... What do you plan to do with a tube tester? "Test tubes" I suppose is the obvious answer. Oddly enough most testers don't do much of a test. Consider:

    [cut]

    -Tube matching for push-pull applications is not a bad idea. If you want to match octals you probably already have a decent tube tester for matching them--a Dynaco MkIII or Stereo 70 will do. The process is tedious but effective. A MaxiMatcher will speed things up if expediency is a priority.

    [cut]

    Good luck!

    I guess my comment above didn't get read... If you have a MkIII you have all you need to match EL-34 or 6550 or 6L6 or KT-88. No mods necessary.

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    peterh

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    Re: Tube Tester

    Post by peterh on Fri Jul 21, 2017 1:42 am

    j beede wrote:
    j beede wrote:A few observations regarding tube testing... What do you plan to do with a tube tester? "Test tubes" I suppose is the obvious answer. Oddly enough most testers don't do much of a test. Consider:

    [cut]

    -Tube matching for push-pull applications is not a bad idea. If you want to match octals you probably already have a decent tube tester for matching them--a Dynaco MkIII or Stereo 70 will do. The process is tedious but effective. A MaxiMatcher will speed things up if expediency is a priority.

    [cut]

    Good luck!

    I guess my comment above didn't get read... If you have a MkIII you have all you need to match EL-34 or 6550 or 6L6 or KT-88. No mods necessary.

    A dynaco MkIII have a common cathode resistor, there is no way to measure the individual
    cathode currents of the output tubes. Same with an dynaco ST70.
    A vta70 is another creature, here individual cathode resistors are implemented.
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    deepee99

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    Re: Tube Tester

    Post by deepee99 on Fri Jul 21, 2017 12:22 pm

    Just as an artifact of curiosity here, and showing how long in tooth I am, but there was a time every Woolworth's (Woodwards in Canada), drug store and Dairy Queen had a tube tester. Who built them, what did they actually test for, and whatever happened to them? There were a kazillion of them, that I remember.
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    j beede

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    Re: Tube Tester

    Post by j beede on Fri Jul 21, 2017 3:48 pm

    peterh wrote:
    j beede wrote:
    j beede wrote:A few observations regarding tube testing... What do you plan to do with a tube tester? "Test tubes" I suppose is the obvious answer. Oddly enough most testers don't do much of a test. Consider:

    [cut]

    -Tube matching for push-pull applications is not a bad idea. If you want to match octals you probably already have a decent tube tester for matching them--a Dynaco MkIII or Stereo 70 will do. The process is tedious but effective. A MaxiMatcher will speed things up if expediency is a priority.

    [cut]

    Good luck!

    I guess my comment above didn't get read... If you have a MkIII you have all you need to match EL-34 or 6550 or 6L6 or KT-88. No mods necessary.

    A dynaco MkIII have a common cathode resistor, there is no way to measure the individual
    cathode currents of the output tubes.  Same with an dynaco ST70.
    A vta70 is another creature, here individual cathode resistors are implemented.

    What you say is correct when running the output in push-pull mode. Running the MkIII (or one channel of a ST-70) single ended facilitates pretty effective cathode current matching--one tube at a time. In the case of the ST-70 the channel not being used for matching should be run push-pull.
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    j beede

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    Re: Tube Tester

    Post by j beede on Fri Jul 21, 2017 4:08 pm

    deepee99 wrote:Just as an artifact of curiosity here, and showing how long in tooth I am, but there was a time every Woolworth's (Woodwards in Canada), drug store and Dairy Queen had a tube tester. Who built them, what did they actually test for, and whatever happened to them? There were a kazillion of them, that I remember.

    Those were typically simple emissions testers mounted over a large storage cabinet full of replacement tubes for sale. I believe those machines were marketing bonanzas as people would buy replacement tubes hoping to avoid the TV repairman and his house call and bill.

    I knew people who would periodically open their perfectly working set, pull all the tubes, head over to Radio Shack or Sears and test them all. They would usually buy one or two replacement tubes (whether the need was indicated or not), go home and (try to) plug them all back in from whence they came.

    My B&K 707 resembles one of those old Walgreens testers. Cool.
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    peterh

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    Re: Tube Tester

    Post by peterh on Fri Jul 21, 2017 4:43 pm

    j beede wrote:
    peterh wrote:
    j beede wrote:
    j beede wrote:A few observations regarding tube testing... What do you plan to do with a tube tester? "Test tubes" I suppose is the obvious answer. Oddly enough most testers don't do much of a test. Consider:

    [cut]

    -Tube matching for push-pull applications is not a bad idea. If you want to match octals you probably already have a decent tube tester for matching them--a Dynaco MkIII or Stereo 70 will do. The process is tedious but effective. A MaxiMatcher will speed things up if expediency is a priority.

    [cut]

    Good luck!

    I guess my comment above didn't get read... If you have a MkIII you have all you need to match EL-34 or 6550 or 6L6 or KT-88. No mods necessary.

    A dynaco MkIII have a common cathode resistor, there is no way to measure the individual
    cathode currents of the output tubes.  Same with an dynaco ST70.
    A vta70 is another creature, here individual cathode resistors are implemented.

    What you say is correct when running the output in push-pull mode. Running the MkIII (or one channel of a ST-70) single ended facilitates pretty effective cathode current matching--one tube at a time. In the case of the ST-70 the channel not being used for matching should be run push-pull.

    Touche ! You got me there ! Never thought of that.

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