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OT Need help to ID this tube

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  • OT Need help to ID this tube

    I was given this tube by an old time electrician who is unfortunately long gone.
    I vaguely remember that he said it was used in some type of radio transmission apparatus.
    I clearly remember he said it had cost many thousands of dollars new.
    I wish I had asked him for more info back then (about 18 years ago).
    I've been cleaning up and came across this and don't know anything about it.
    For size reference, in the top pic, its sitting on 5/4 x6" lumber.
    It weighs about 8 pounds.
    I'm assuming he put the hose clamp on to protect the heat sink fins, which appear to be copper or high red brass.

    TIA :-)








  • #2
    http://www.google.com/url?sa=t&rct=j...9R1Ip6DTapotMg

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    • #3
      I did find this.

      http://www.rfeworld.com/datasheets/7237A.pdf

      However aside from knowing its a triode I don't understand much of this data sheet.

      Apparently this link is the same as the one posted above by fredf.
      Last edited by yf; 05-31-2012, 06:00 AM.

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      • #4
        That's a Monster - 10kW at 30MHz or 6kW at 50MHz, boy that would hurt...

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        • #5
          The power and operation figures are mostly for 2 tubes in push-pull, so not *quite* as large....

          But the tubes are clearly for medium power usage among transmitter tubes.

          Note the driving power of 430 watts, 0.6 amps grid current... That's the power needed at the INPUT to get the listed output power...... you need a very substantial amplifier just to DRIVE the tube to those outputs
          1601

          Keep eye on ball.
          Hashim Khan

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          • #6
            That looks very much like one of the output tubes used in the 10 Kw transmitters we had at the Naval transmitting site that I was stationed at in the late 60's.

            Didn't get any pics unfortunately, being military and all.

            I do, however, have a 1 Kw AM transmitter out back that would probably work as a driver for it. Probably could cut you a deal.
            Guaranteed not to rust, bust, collect dust, bend, chip, crack or peel

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            • #7
              If it was used in a push-pull configuration, those were usually changed out in pairs. If one died, you changed them both. That may be the survivor. Also, I don't know if that one falls into this category, but I seem to remember that larger tubes could be sent off and rebuilt.

              Stirring up some memories now...
              Last edited by browne92; 05-31-2012, 10:55 AM.
              Definition: Racecar - a device that turns money into noise.

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              • #8
                Originally posted by KIMFAB
                That looks very much like one of the output tubes used in the 10 Kw transmitters we had at the Naval transmitting site that I was stationed at in the late 60's.

                Didn't get any pics unfortunately, being military and all.

                I do, however, have a 1 Kw AM transmitter out back that would probably work as a driver for it. Probably could cut you a deal.
                Small world. I was also at a couple of NavRadTransFac's. Dixon and Deep Freeze. Worked on the AN/FRT-39's, 40's, 72's, and 84's. For those not familiar these are 10kw-100kw HF transmitters. That tube is very similar to what we used, but the ones we used had ring electrodes at the bottom instead of pins. Typically the contacts and fins were silver-plated copper. Also there was usually beryllium in the ceramic so disposal was controlled. I believe the exciter section on the FRT's were 1kw.

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                • #9
                  First of all thank you to all who replied.
                  The replies raised more questions.

                  How can I test this?
                  If good, can I sell it?
                  If not, does it have any scrap value, or
                  should I make it into a table lamp? :-)

                  I still don't understand the data sheet, but I now know its a
                  transmitter.

                  Thanks for the responses.

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                  • #10
                    I have a few similar tubes, though not quite as large or powerful as that one. I was definitely thinking of the table lamp idea. I would power up the filament of course, which would make it into a heater. With some type of ornate grid suspended above, it would become a place to keep your coffee cup warm
                    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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                    • #11
                      About the only test you could do would be to use an ohmmeter and measure the filament resistance. Otherwise you need to be able to bias it to measure conductance which probably isn't feasible. It won't tell you that the tube is good, but will tell you that the filament should work. This is going back a ways, but if i remember right it should measure between 5-15 ohms. Someone correct me if they know better. The heat sink is the plate and should measure open to any other terminal. One terminal may or may not be connected (shorted) to the filament connections. That would be the cathode. The grid terminal also should be open to any other terminal. Just measure methodically between all combinations of two terminals to find the filaments. By the way, the hose clamp would be to make the plate connection. Generally a strap would slide underneath the clamp.

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                      • #12
                        I just noticed the link to the datasheet. Filament would be 0.38 ohms.

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                        • #13
                          Originally posted by Forestgnome
                          I just noticed the link to the datasheet. Filament would be 0.38 ohms.
                          That is the hot resistance at nominal voltage input with 33A of current. Cold, it will look like a short circuit which for most purposes 0.38 Ohms already is . A quick trip to a car's battery should produce a nice bright yellow glow.

                          These would have been installed push-pull to reduce harmonics and would have been plate-modulated class C amplifiers, or even class B if derated. They can also be used as modulator tubes for even more powerful systems, but RF is their sweet spot. As class C they could have been used in RTTY and other "digital" modes.

                          Be cautious of beryllium in the ceramic - assume it is there and treat it accordingly until you know otherwise.

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                          • #14
                            The data sheet shows a three pin array, with the center and slightly wider pin being a center tap on the filament. The other two pins are then the filament. I believe that since there's so much power involved just in the filament, that those pins would all be used to help draw heat away, either through the socket or through the connecting wires. If you wanted to power it just for laughs, it might be good to also use a method of drawing heat out of those pins- otherwise the glass might crack.
                            I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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                            • #15
                              Everything about those tubes including the attachments would have been in the forced air stream. I worked with similarly sized tetrode devices and as I recall the heater/filament circuit would kick in the blowers and the HV needed to have a "thermal invite" before it would be tripped on.

                              That was the era of cheap energy

                              All the small RF gear I worked on in the 70's went solid state. The last tube transmitter I designed went into production in 1975.

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