Gates of Hell - Posting for K3FEF.

Discussion in 'Amplitude Modulation' started by KA4KOE, Jun 7, 2017.

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  1. WA3VJB

    WA3VJB Ham Member QRZ Page

    Update, Friday evening.
     

    Attached Files:

    K5UJ likes this.
  2. KA4KOE

    KA4KOE Ham Member QRZ Page

    They're wired backwards :)
     
  3. KA4KOE

    KA4KOE Ham Member QRZ Page

    Bob Henry quote worth remembering vis-a-vis 833 tubes:
    I just love those 833A's ... "They're Glass Soldiers on the front line - poised and ready for service!"
     
  4. W7TFO

    W7TFO Platinum Subscriber Platinum Subscriber QRZ Page

    833A's...more like a skinned rabbit.

    But prettier than a bunch of bully-tube bomb 6146's.

    73DG
     
  5. WZ5Q

    WZ5Q Ham Member QRZ Page

    You couldn't tell looking at mine, too much nicotine!
    The Operator I got it from smoked like a train.

    RCA BTA-1m 833s.jpg
     
  6. W7TFO

    W7TFO Platinum Subscriber Platinum Subscriber QRZ Page

    Well, you gotta' love any glass tube with a 350W. plate....

    73DG
     
  7. K4KYV

    K4KYV Premium Subscriber Volunteer Moderator QRZ Page

    Notice that RCA mounted them upside down. Just as they did 849s, 204As and 851s. In fact, the old RCA transmitting tube manuals said they were supposed to mount that way.
     
  8. WA3VJB

    WA3VJB Ham Member QRZ Page

    For all the types named, or just the 833A ?

    Had to be something about the tube's construction, because the tube manual wouldn't address practical mounting considerations. Wonder if you ever heard why?

    Physical orientation can be important because of the innards. Many of the 807 type tubes, various manufacturers, suffered inter-electrode shorts when the tube was operated horizontally. The fortified 807W and military 5933 were recommended for such applications.
     
  9. W7TFO

    W7TFO Platinum Subscriber Platinum Subscriber QRZ Page

    Yep, the 250-Watt base triodes like those mentioned even had the printing on the bases (there were two) oriented to show filament & grid on top.

    The rectifiers, like the 869B were fil down.

    I just love old tube lore....

    73DG
     
  10. K4KYV

    K4KYV Premium Subscriber Volunteer Moderator QRZ Page

    But I have seen plenty of vintage photos of late 20s and early 30s transmitters that had them mounted base-down with the plate on top. I have often wondered if like Paul said there was something about the tube's construction that they recommended mounting them plate-down, and that operating them plate-up could somehow shorten tube life.

    Those tubes, also the 833-A, can be safely operated in a sideways position provided the filament/plate structure is oriented in a vertical plane so that filament sag doesn't cause a filament to grid short. I always store transmitting tubes for any length of time vertically, since filament sag could occur even with a cold tube stored horizontally for an extended period.
     

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