FISHER 400 TUBES

Discussion in 'Fisher' started by rudpra, Aug 8, 2017.

  1. rudpra

    rudpra Active Member

    Messages:
    170
    Glad to be back its been a while my 400 quit working checked the 7868 tubes 3 are fisher 1 is Sylvania,well
    the Sylvania is dead hardly registering on EMC 215 tube analyzer, 2 of the Fisher are good and 1 low good,
    I guess its time for McShane Electroharminics ? other opinions....Thanks...
     
  2. AlTinkster92

    AlTinkster92 AK Subscriber Subscriber

    Messages:
    3,026
    Location:
    NC
    Yep, Jims the tube guy to go too, stay off the auction site...
     
  3. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

    Messages:
    19,962
    Location:
    Glen Burnie Md.
    Just be advised, the EH7868 pins are slightly larger and once you insert them you can't go back to old stock unless you can score some new sockets. Otherwise the EH's are good tubes.
     
  4. rudpra

    rudpra Active Member

    Messages:
    170
    I guess you cant trust the 7868 tubes that are sold on Flea bay thanks again....
     
  5. gadget73

    gadget73 junk junkie Subscriber

    Messages:
    32,777
    Location:
    Southern NJ
    Thats very much hit and miss. I have 8 "NOS" ones that came from Ebay at a good price, one is a "set" of 4 that are grossly mismatched, the other 4 actually match up reasonably well. They came from different places at different times, the badly mismatched set are Sylvania, the good ones are RCA.

    I have a set of EH 7868 from Jim in my Sherwood S-7000. No complaints about them. The old production ones are used in my S-5500II. They both sound excellent.
     
  6. rudpra

    rudpra Active Member

    Messages:
    170
    Jim said that he is out of stock 7868,new stock will be coming soon ,does that mean that old stock might be better and if so any production dates and production numbers.....
     
  7. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

    Messages:
    19,962
    Location:
    Glen Burnie Md.
    No. I just means the EH7868 is becoming more popular as the "OLD STOCK(1960's era)" wears out and the remaining stock gets very thin, matching ones from dealers are getting more expensive. Get the EH's now before they go up in price when the stocks of "old stock" disappear.

    I'm not pulling the old "Gloom and Doom" thing here. It's just that the 7868 was a very late comer to the show and aren't as plentiful as the 7591's.
     
    Bill Ferris likes this.
  8. rudpra

    rudpra Active Member

    Messages:
    170
    Can you use adapters to convert to 7591 in worse case.....thanks
     
  9. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

    Messages:
    19,962
    Location:
    Glen Burnie Md.
    You'd have to re socket it. No adapters for 7868's to 7591's. I'm not going to tell you which way to go , but I will tell you that old stock 7868 (60's made) that are any good are either being hoarded or are selling for ridiculous prices. The russian 7868's are about 85-90% of the old stock when tested against the old stock Westies. Meaning they tend not to play well with others when run at full dissipation. None of the Russian tubes do for very long.And that is a manufacturing fault. But run them at 70% to 80% of max dissipation(you'd end up running the old ones at the same levels to save them anyway) and they are very good, stable, sounding very much like the originals. I've put them in at least 7 400's (3 of which are or were mine) and haven't had any problems or gripes about them. The oldest set were gotten in 2010 and to my knowledge are still running. If your only gripe with them is the pin size, this actually works out quite well with them. Granted you'll have a hard time with old stock tubes after EH's were installed due to the pin size, but if you have EH's in one, the sockets are tight against the pins and don't loosen (I've never seen one loosen up after an EH went in).

    The other plus is when you get EH's from a dealer who tests them with a custom rig built specifically for testing tubes beyond their max capabilities, you're practically guaranteed that they match for cathode draw. Getting them off E-PREY is, like Gadget said, is hit or miss. I'd wait for Jim to get a quad. He'll make sure they match within 2ma max. With that as a start, and installation of an IBAM or IBBA board will ensure you can match them up to whatever level you want them at with out problems, either during adjustment or afterwards. My personal experience with the EH7868's, EH7591's and Tungsol 7591's is that I have yet to have to readjust any of my EH or Tungsol 7868 or 7591's in a unit, as long as they stay in that unit. I check them every 6 months of use, logging each test. 1ma variance over 10 years from initial installation on a quad of 7868's and or 7591's is nominal for my tubes. I've never had one change more than 1ma unless the wall voltage changes by more than 5 volts.
     
  10. superjojo

    superjojo Active Member

    Messages:
    225
    Ive been thinking about trying out the EH too. It probably takes some finesse to install them the first time. What's the best method as to not damage a tube or socket?
     
  11. Patrice B

    Patrice B AK Subscriber Subscriber

    Messages:
    2,008
    Location:
    Montréal, Canada
    The Tubestore has them in stock. I ordered a quad last month for a Sherwood and they bias at 1-2 ma close.
     
  12. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

    Messages:
    19,962
    Location:
    Glen Burnie Md.
    Spray some FADERLUBE on the pins. Set the tubes on the socket with the pins lined up, and push down while moving the tube in an arc around the socket to get the pins past the initial resistance. They will go in all of a sudden so don't do a HULK on them. Moderate pressure, while moving the tube in a slight arc gives the best results.
     
  13. superjojo

    superjojo Active Member

    Messages:
    225
    Thank you.


    what can I use instead of FADERLUBE? Maybe just soak them with contact cleaner or use a little Noalox (which is a anti seizing compound)?

    And I assume once they are in, I can easily remove and reinsert without effort the second time.
     
  14. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

    Messages:
    19,962
    Location:
    Glen Burnie Md.
    Contact cleaner has no lubricant, which is why I suggested Faderlube. I wouldn't use the noalox. Too much risk of no contact for me.
    If the Faderlube isn't in your kit, and you need some electronics lube, go down to Home Depot and get a can of CRC 2-36 electronics lube. It lubes pretty much like faderlube, but without the De-Oxit in it. Electric section Home Depot.

    I was gonna say something about popping cherries.........BUT yeah you can easily remove and re-insert them afterward. They'll be tight.
     
  15. superjojo

    superjojo Active Member

    Messages:
    225
    Larry I was thinking the same thing about popping cherries but I wouldn't dare say it.

    But as far as lube is concerned, come to think of it, I do have an old can of CRC 2-26 in the garage, I placed it there around the time Bill Clinton was president.

    If I remember right that stuff has to dry completely (hours?) before energizing a circuit. The suspense is going to kill me, but perhaps the little that will use on the pins I wouldn't have to wait so long.
     
  16. larryderouin

    larryderouin Do I get Food, Med's, or more gear this Month? Subscriber

    Messages:
    19,962
    Location:
    Glen Burnie Md.
    Just a lite coat on the tube pins, and touch the ends to a paper towel. Install and power it up. No problems, do it all the time.
     
  17. gadget73

    gadget73 junk junkie Subscriber

    Messages:
    32,777
    Location:
    Southern NJ
    Just be careful with the sockets. Not sure if Fisher used the same ones Sherwood did, but my Sherwood sockets are coming loose from the metal mounting frame. They've never been stretched either, even removing stock tubes needs me to poke a screwdriver in there to hold the insulator down while removing the tube.
     

Share This Page