1. You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
    Dismiss Notice

matching tubes

Discussion in 'Worldwidedx.com Amateur Radio Club' started by 517 Leroy, Sep 12, 2018.

  1. 517 Leroy

    517 Leroy New Member

    Joined:
    Sep 1, 2018
    Messages:
    12
    Likes Received:
    6
    How important is all matching tubes? I got a Scout 20 8 tuber in trade, works good but has different brand tubes.


     
    #1 517 Leroy, Sep 12, 2018
    Last edited: Sep 12, 2018

  2. 543_Dallas

    543_Dallas Sr. Member

    Joined:
    Jul 25, 2011
    Messages:
    1,943
    Likes Received:
    2,110
    It would be ideal if they were all matched with a tube tester but it will work fine with different brands in it as long as they all are good tubes. Sweep tubes are too scarce and expensive to be picky.

    Some of the local guys went out and bought tube testers. I repaired one sweep tube amp and found that if you hold an am carrier for several seconds the good tubes start to turn red faster than the weak ones and the duds do nothing. Don't over do it though. Sweep tubes have paper thin anodes.
     
  3. Shockwave

    Shockwave Sr. Member

    Joined:
    Sep 19, 2009
    Messages:
    2,874
    Likes Received:
    1,304
    If anyone wants to trade tubes that turn red for ones that won't, I'm happy to make that deal :) The truth is if you get rid of the ones that don't turn red, the ones that do won't have to work so hard and you'll see more power out. I am a fan of the "red plate" test that 543 mentions above because it's an indication of how the tube is responding to both DC and RF under load. Lots of factory matching is only done with DC. As 543 says, don't over due it with sweep tubes. You only have to key the amp long enough to spot the first signs of color change on the plates. Don't wait for the weaker ones to change color because you already have your results once the first one does.
     
  4. 517 Leroy

    517 Leroy New Member

    Joined:
    Sep 1, 2018
    Messages:
    12
    Likes Received:
    6
    I finally got to open it to preform the test, they all seem to glow the same but one is dim, then when I key it glows really bright then when I modulate it will go dim. I guess its a bad one.
     
    #4 517 Leroy, Dec 14, 2018
    Last edited: Dec 14, 2018
  5. nomadradio

    nomadradio Analog Retentive

    Joined:
    Apr 3, 2005
    Messages:
    2,646
    Likes Received:
    2,388
    If it isn't already it will be soon.

    The gray "plate" structure inside the glass isn't supposed to light up.

    Unless it's a big tube the size of a fruit jar. They're different.

    Your Scout 20 is either set up wrong, or some parts have gone bad from 3 or 4 decades of age. There is more than one kind of problem that can cause the tubes to overheat and "cherry", showing color on the plate structure inside.

    73
     
    517 Leroy likes this.
  6. 517 Leroy

    517 Leroy New Member

    Joined:
    Sep 1, 2018
    Messages:
    12
    Likes Received:
    6
    Guess I'll get on eBay and start looking for tubes. 6lq6s
     
  7. rabbiporkchop

    rabbiporkchop Sr. Member

    Joined:
    Jan 18, 2007
    Messages:
    1,790
    Likes Received:
    629
    Economy Electronics Inc
    225 Frontage Road
    Lonoke, AR 72086
    Phone:(501) 676-3234

    Last I checked, this guy has a warehouse of obsolete stuff like that.
     
    517 Leroy and Shadetree Mechanic like this.
  8. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

    Joined:
    Oct 23, 2017
    Messages:
    1,620
    Likes Received:
    1,447
    Unfortunately their website seems to be down.
     
  9. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

    Joined:
    Oct 23, 2017
    Messages:
    1,620
    Likes Received:
    1,447
    There are also a handful of other tubes that cross reference to this one. I don't know if they are drop in replacements but I think they are close enough to work from what I have read.
     
    517 Leroy likes this.
  10. 517 Leroy

    517 Leroy New Member

    Joined:
    Sep 1, 2018
    Messages:
    12
    Likes Received:
    6
    Thanks! I'll check them out out
     
  11. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

    Joined:
    Oct 23, 2017
    Messages:
    1,620
    Likes Received:
    1,447
    Here is my thread on my Context amp. It uses the 6LQ6 in a 1 driving 4 configuration. One of my posts contains info from Ken's electronics about tube swapping to the 6KG6. There are other tubes that are a direct swap. Looking through my notes now.
    https://www.worldwidedx.com/threads/contex-500-tube-amp.226894/page-4
     
  12. jessejamesdallas

    jessejamesdallas Sr. Member

    Joined:
    Apr 4, 2005
    Messages:
    1,314
    Likes Received:
    685
    I have a bran new set of 4 matching RCA 6JE6A-6LQ6 that I bought from Tube Depot a few years ago for spares to my Kicker 500 Amp (1x3)...Last set of matching RCA's I seen were going for $350+...

    Hard to find 4 matching NOS tubes...most are sold as singles or pairs.
     
    #12 jessejamesdallas, Dec 17, 2018
    Last edited: Dec 17, 2018
    Shadetree Mechanic likes this.
  13. Shockwave

    Shockwave Sr. Member

    Joined:
    Sep 19, 2009
    Messages:
    2,874
    Likes Received:
    1,304
    The problem with the 6LQ6 tube is it wasn't only popular in CB linears. It was also used in some of the most expensive audio amplifiers ever built in matched sets of 8! If you own one of those 8 tube AF amps, it doesn't matter if the tubes cost $250 each. Those owners will pay anything to keep them alive.
     
    Shadetree Mechanic likes this.
  14. 517 Leroy

    517 Leroy New Member

    Joined:
    Sep 1, 2018
    Messages:
    12
    Likes Received:
    6
    I found a matching set of 4 RCA 6lq6s for $120 used, he says they've been tested. Good deal or no?
     
  15. nomadradio

    nomadradio Analog Retentive

    Joined:
    Apr 3, 2005
    Messages:
    2,646
    Likes Received:
    2,388
    If they were tested in an amplifier, maybe.

    A tube tester is good at identifying bad tubes.

    A tube that checks good in a tester may still produce a blue flash and break down under load in an amplifier.

    Given the odds, I would recommend getting five or six good tubes to run a 4-tube amplifier. We recently fixed up a Maco 750 that used a terribly-rare tube called the M2057. It arrived with eight tubes in it, and three of them flunked my tube tester. Found five more to use that tested okay. One of those went "SNAP" after the amplifier was keyed a dozen times or so. The tester confirmed that this tube now tested bad.Tested okay before that.

    Same thing happened to another tube after running it a while.

    So now, after starting with a total of 13 tubes, it has eight that work in it.

    Only a question of how long before another one goes "SNAP!".

    Your mileage may vary. The Maco amplifier is famous for being hard on the tubes.

    73
     
    517 Leroy and Shadetree Mechanic like this.

Share This Page

  • About Us

    The WorldwideDX Radio Forum was originally established in 2001. We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. We are working every day to make sure our community is the best Radio Hobbyist's site.
  • Like us on Facebook

  • Premium VIP Member

    The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. Care to buy us a beer? We'd really appreciate it!

    Donate to us!