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
Dismiss Notice
This forum does not allow a single user to have more than one username. If anyone wants to change their username contact an admin and it will be done. Multiple accounts belonging to the same member will be deleted without warning.

help with amp conversion

Discussion in 'General CB Services Discussion' started by Glazierman, Jun 24, 2008.

  1. Glazierman

    Glazierman Member

    Joined:
    Apr 9, 2005
    Messages:
    76
    Likes Received:
    0
    I come across this amp and not sure of two driver tubes , but think other six are 8950's would like suggestions on tube replacement and links if any one can help thanks will try to show pics .http://i25.photobucket.com/albums/c70/glazierman/100_1081.jpg
    http://i25.photobucket.com/albums/c70/glazierman/100_1082.jpg
    http://i25.photobucket.com/albums/c70/glazierman/100_1086.jpg


     
    #1 Glazierman, Jun 24, 2008
    Last edited: Jun 24, 2008

  2. dudmuck

    dudmuck Active Member

    Joined:
    May 21, 2007
    Messages:
    482
    Likes Received:
    9
    The drivers have the same sockets and wired the same as the other six?
    If so, then its was probably just two 8950 driving six 8950.

    The 8950 was a bit of an oddball with its 12volt heater.
    Most other sweep tubes were 6 volt heaters.

    The Siltronix 1011 used the 8950 tube, so you might find information from notes on replacing the tube in that radio.
     
  3. fnkycoldmedina

    fnkycoldmedina Well-Known Member

    Joined:
    May 18, 2005
    Messages:
    2,267
    Likes Received:
    92
    8-8950`s ......ha....might as well just buy another amp.those are the most expensive sweep tubes around.
     
  4. ExitThirteen

    ExitThirteen Grumpy and Cranky

    Joined:
    Apr 18, 2008
    Messages:
    1,930
    Likes Received:
    1,434
    If the amp takes 8 x 8950's, you can sub in 8 x 30KD6, wire the filaments in series in 2 groups of 4, and wire the filaments to your AC line switched. 4 x 30v filaments in the 30KD6's = 120v. I used to do that with the Maco 200's all the time, worked fantastic, and a LOT cheaper too. Granted, the 8950 tubes are 40 watts max plate dissipation, vs. 34 watts for the 30KD6, but losing a couple watts is a small price to pay for trying to buy 8 x 8950's. Another alternative is use 6LF6 tubes, and tie 2 tube filaments in series and use the 12v output on the filament transformer, but 6LF6 tubes are also pricey. If you really want to keep full output, you can substitute 8 x 27LF6 tubes and wire the filaments up same as the 30KD6 mentioned above. Hope this helps!


    -Exit
     
  5. Glazierman

    Glazierman Member

    Joined:
    Apr 9, 2005
    Messages:
    76
    Likes Received:
    0
    I'm not so sure about the front two tubes being the same if you look at the pics you'll see that two of the sockets have a slot in them where the other six sockets do not ??
     
  6. ExitThirteen

    ExitThirteen Grumpy and Cranky

    Joined:
    Apr 18, 2008
    Messages:
    1,930
    Likes Received:
    1,434
    Upon further inspection, the only difference I see between the driver section (2 tubes) and the final section (6 tubes) is that the 2 driver tubes are grid tuned with a variable capacitor, and the final 6 tubes are run grounded grid. Looks like you could still run all of the same tube, and the sockets are physically the same. Just make sure you use a tube that has at least 34 watts of plate dissipation per tube. If you're unsure of what tube to run or which tube has 34 watts of plate dissipation or better, you can google a tube number and you get info on the tube there.
    Good luck to you!


    -Exit
     

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!