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Clegg Laboratories - Trivia - There Were 2 Clegg 99'er Models

Discussion in '"Boat Anchor" & Classic Equipment' started by WA2CWA, Sep 12, 2021.

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  1. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    There aren't any tubes similar to the 8236 -- it was the most powerful sweep tube ever, and manufactured only by Tung-Sol with no other source.

    I'd forget that.
  2. WA2CWA

    WA2CWA Ham Member QRZ Page

    I do know the capabilities of the 8236 (power output, plate dissipation, etc.). It's been several years since I took the cover off the Apollo so I really don't remember what work was already done. I do recall some loose wires and a few components hanging in mid air. I'm probably not going to try and bring the Apollo back to similar power specs but the external cosmetics look very good and would look even better powered up and sitting next to the Venus. The 6DQ5 is an exact replacement for the 8236 but obviously no where near as robust.

    Lots of things I'd like to do in the shack and with the equipment with problems, not working, or moss growing all over them. The problem is finding enough time to diddle with the equipment on the workbench. Of course, documentation is not a problem. :)
  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Indeed, a pair of 6DQ5s would probably work, at about half the power, maybe 150-200W PEP output.

    The 8236's could run about 350W PEP output, but today may be impossible to find. If any are found. they'd probably be 40 years old...or more.:p
  4. WA2CWA

    WA2CWA Ham Member QRZ Page

    Probably could even squeak in a pair or more of 6146B's. Would have to really check the specs. I believe pate dissipation is slightly higher then the 6DQ5's.
  5. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    6146B has slightly higher dissipation rating than the 6DQ5 (27W vs. 24W) but since the Venus already has one (6883), using that one to drive two seems silly. Also, I don't know if the 6DQ5 or 6146B would survive operation at Ep = 1500V, which is what the Apollo supplies. The 8236 was rated 1200V and the Apollo pushed it a bit. The 6DQ5 is rated 990V max and the 6146B is rated 750V max although ham rigs have often pushed them above that.

    Using four of them in parallel might work but would likely require changing the input and output tank circuits, but using a single 4X150A or something like that seems easier and could create more output and more headroom, and use only one socket.
  6. WA2CWA

    WA2CWA Ham Member QRZ Page

    If the previous owner already has the socket installed (I just don't remember) then I'll continue with it and finish the mod although I don't have any paperwork as to the specifics of the actual mod. If someone has that info, that would be great, since I have about 25 or 30 4X150's and 250's somewhere in my inventory.
    If not, I'll just wing it with my brilliant mind :eek::eek:

    As far as a 6 meter linear, I'm not barren. In the equipment stash, there is a solid state 6M brick, the homebrew 6146B pair, Gonset 913A, and the big boy 6N2 Thunderbolt.
  7. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Using a 4X150A or 4CX250B should be super easy. The Apollo already has 1500V B+ and regulated screen voltage which is appropriate, and adjustable grid bias which is also appropriate.

    It's mostly a mechanical modification with the socket, chimney and blower.

    The original screen supply uses only a gas tube regulator and may be insufficient for two tubes, but for one tube should work fine.

    As Nike says, "Just Do It."
  8. AC0OB

    AC0OB Platinum Subscriber Platinum Subscriber QRZ Page

    I am currently running a 6DQ5 in a Turbo HT-40 at a plate voltage of 850 volts with good reliability and I can say the plate dissipation is conservatively rated.

    I don't think I would try it at 1500V sustained.

    The sweep tube 6LW6 was the latest high power sweep tube for the large color television sets and even that one was only good to 1kV sustained.

    If you look at the tube specs for the 8236 the suggested Vp was only 900 volts for ICAS.

    Last edited: Sep 16, 2021
  9. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    That's the rating for "typical operation." The "maximum ratings" indicate 1200V.

    Clegg pushed the envelope a bit and actually used 1500V, but I never heard of one failing.
    Then, Kenwood used about 900V on 6146Bs (S2001s) in their hybrid rigs for many years, which is also above the tube's maximum ratings and they got away with that for a really long time. Tubes didn't fail in those, either.

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