1944 BC-610 E back home!

Discussion in 'Amplitude Modulation - AM Fans' started by N6YW, Jan 28, 2019.

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  1. K4KYV

    K4KYV Subscriber QRZ Page

    Compare the 6C21, 450TL, 750TL and 1000T. The physical sizes of the bulbs are all close to the same, except for the 750TL, which is quite a bit larger. The filament current of the 750TL is the highest of the four. The 6C21 is rated at only 300 watts plate dissipation, but it has enormous peak current, voltage and power ratings. The 450TLis rated at 450 watts plate dissipation, the 750TL at 750 watts, and the 1000T, at 1000 watts. The 750TL is the physically largest, and has the most robust filament, at 21 amps. Its maximum output rating is about the same as that of the 1000T, but it looks like the 750TL is the most robust of the four.

    Rated plate dissipation of these tubes does not tell the whole story.

    http://tubedata.milbert.com/sheets/140/6/6C21.pdf

    http://tubedata.milbert.com/sheets/088/4/450TL.pdf

    http://tubedata.milbert.com/sheets/088/7/750TL.pdf

    http://tubedata.milbert.com/sheets/088/1/1000T.pdf
     
  2. AF7XT

    AF7XT Ham Member QRZ Page

    Those that saw war emergency power (water alcohol injection and elevated rpm) for any length of time had even shorter TBO.
    Some of the Merlin engines I saw were V-1650 Packard used in later P-51. These were removed and set aside , never rebuilt and generally had less than 200 hrs on them ! On inspection they were well worn with the rods and pistons seeing most of the wear with the exhaust valves a close second.
    Generally sporting around 1,500 HP as delivered they could be modified for 2,500 HP for brief periods.
    As a comparison the Allison V-1710 had a TBO of more than 1,500 hrs. Then again it never got the two speed supercharger and was never rated near 1,500 hp Save for the turbo-supercharged G engine used in the P38.
    Hint, I played with hydroplanes when I was much younger :)
     
    N2EY likes this.
  3. N2EY

    N2EY Premium Subscriber QRZ Page

    The 750TL is clearly a very different tube than the other three. Different socket, much larger bottle, enormous in every way.

    The 6C21, 450TL and 1000T are all the same size and use the same socket. The anode structures are different, though, and the filaments are different too. The 1000T has that weird 1/4 inch rod sticking out the bottom.

    The 1000T filament is 7.5 volts at 15 amps while the 6C21 filament is 8.2 volts at 17 amps. However the 450TL filament is 7.5 volts at only 12 amps.

    The 1000T and 6C21 require that the base be cooled by forced air to avoid overheating the seals. The 450TL doesn't require that.

    The pulse ratings of the 6C21 are....incredible!
     
  4. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I never owned one, but when I was a kid (13-14 y.o.) "Radio Row" in NYC had a few shops with BC-610s that were quite new, on pallets, for in the $100 range, if you could carry them away.

    I had $100 but had to take a subway then a bus to get home, so it was impossible.:p
     
  5. K4KYV

    K4KYV Subscriber QRZ Page

    I have seen it recommended from more than one source, that for continuous duty, the 6C21 filament should be run at 7.5 volts. 8.2 volts boosts peak emission (which you don't need for normal class-B or class-C operation), but at the expense of tube life.

    At 7.5 volts, filament current proportionately calculates to 15.5 amps, so it has almost the same filament as the 1000T.

    I have heard stories that when they shut down Radio Row and seized the property by eminent domain to build the WTC, that a lot of the goodies were simply left in the warehouses to be disposed of along with the building debris, because the owners had limited time to clear out the stuff and didn't think it was worth the effort. I'm not sure but I think it was Timtron who told me, about being in the area right after they had shuttered the stores, and sneaking into one of the abandoned buildings and hauling out a bunch of transmitting tubes.

    I have said many times that I grieved over the tragic loss of life on 9/11, but shed nary a tear over the felling of those buildings.

    That must have been like the feeling that befell those who attended Dayton at the old HARA Arena one year when there was a particularly acute parking issue, and followed the hamfest committee's recommendation to park over at Salem Mall a few blocks away, and take a shuttle bus to the hamfest.
     
  6. W2VW

    W2VW Ham Member QRZ Page

    Who has used or even seen working versions of a 750TL or 1000T in the last 50 years?

    And yes, the pulse ratings are really impressive compared to hamateur ratings.

     
    N2EY likes this.
  7. K5UJ

    K5UJ Ham Member QRZ Page

    I think the closest I ever got was one year at Hara Arena when some guy had two or three bottles for sale outside, they were either 450s or 750s, can't remember which, but they were in the original spring supported boxes. They were probably THs though.
     
  8. K4KYV

    K4KYV Subscriber QRZ Page

    And they quite likely were gassy. I think those spring-supported boxes date back to the WWII era, and tubes of that construction (Eimac and H&K) gas up after only a few years on the shelf.
     
  9. N6YW

    N6YW Ham Member Volunteer Moderator QRZ Page

    I plan on leaving the 610 on 40 meters for the time
    being. It still needs work and at this point, I’m planning aHV wiring overhaul.
     
  10. W2VW

    W2VW Ham Member QRZ Page

    And the Eimac claim to fame was less internal support structures to gas out.
     

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