A Walk-In Broadcast Transmitter

[Mr. Carlson] likes electronics gear. Mostly old gear. The grayer the case, the greener the phosphors, and the more hammertone, the better. That’s why we’re not surprised to see him with a mammoth AM radio station transmitter in his shop. That it’s a transmitter that you can walk into while it’s energized was a bit of a surprise, though.

As radio station transmitters go, [Mr. Carlson]’s Gates BC-250-GY broadcast transmitter is actually pretty small, especially for 1940s-vintage gear. It has a 250 watt output and was used as a nighttime transmitter; AM stations are typically required to operate at reduced power when the ionosphere is favorable for skip on the medium frequency bands. Stations often use separate day and night transmitters rather than just dialing back the daytime flamethrower; this allows plenty of time for maintenance with no interruptions to programming.

If you enjoy old broadcast gear, the tour of this transmitter, which has been rebuilt for use in the ham bands, will be a real treat. Feast your eyes on those lovely old bakelite knobs and the Simpson and Westinghouse meters, and picture a broadcast engineer in white short sleeves and skinny tie making notations on a clipboard. The transmitter is just as lovely on the inside — once the plate power supply is shut down, of course, lest [Mr. Carlson] quickly become [the former late Mr. Carlson] upon stepping inside. Honestly, there aren’t that many components inside, but what’s there is big – huge transformer, giant potato slicer variable caps, wirewound resistors the size of paper towel tubes, and five enormous, glowing vacuum tubes.

It’s a pretty neat bit of broadcasting history, and it’s a treat to see it so lovingly restored. [Mr. Carlson] teases us with other, yet larger daytime transmitters he has yet to restore, and we can’t wait for that tour. Until then, perhaps we can just review [Mr. Crosley]’s giant Cincinnati transmitter from the 1920s and wait patiently.

18 thoughts on “A Walk-In Broadcast Transmitter

  1. English is not my mother language. And I hate to rant and look like a “Grammar Nazi” (we´re not talking about your gramma, Dan).
    But sorry it´s just hard to believe the author re-read his article.
    What about “this allows plenty of time for maintenance with no interruptions to programming.” ? really ? There´s JTAG on this mammoth ?
    ” The transmitter is just as lovely on the inside ” as lovely as WHAT ?

    Being paid for pissing articles like that… sorry it is “Write as you talk”.

    1. “Programming” is what folks in the radio industry refer to their schedule as. As a non-native English speaker, it’s forgiveable that you wouldn’t know this. But as a non-native, why would you go on this rant without looking the word up in the dictionary?

      “As lovely” — he just finished describing the “lovely Bakelite knobs”. I presume that’s what he’s referring to. (“Bakelite” could arguably be capitalized. Depends on whether the knobs are real or just bakelite-esqe. Meh.)

      And while you correctly spelled “Dan.Baloney@hackaday.com”, you typoed it to “Bam” in the nickname field. Don’t you proofread these things?!?!? It’s hard to believe that we pay you to write comments like this! One more slipup of this magnitude and we’re taking away your readership license.

      1. I will cop to incorrectly marrying off [Mr. Carlson] by referring to him as [the former Mr. Carlson] rather than [the late Mr. Carlson], though. Duly fixed with a strikeout, just so nobody thinks I’m trying to pull a fast one.

        And that baloney thing just never gets old. It’s just great to see someone so clever as to make that association between my name and the luncheon meat-like product. You must be so proud to have rediscovered what so many six-year-olds before you have considered comedy gold. Oh, the hilarity!

    2. Are you quite serious? No there isn’t JTAG on a 40s transmitter, the term “programming” refers to the scheduled broadcasting the radio station produces, as in music, news, etc. Wow.

    3. >What about “this allows plenty of time for maintenance with no interruptions to programming.” ? really ? There´s JTAG on this mammoth ?

      How about this, bud, if english isn’t your native language, don’t go critiquing it when a word is used in a way you’re not familiar with, but in a way native speakers are ;)

  2. Part of the first ~10 years of my career included vacuuming flies out of 50kW transmitters and the tower networks in the wee hours of the night. Some transmitters were bigger than NYC apartments inside…

    I also know one chief engineer who was permanently disabled from getting zapped while working solo in a hot transmitter Never, never work solo on such a transmitter when it’s hot, or not properly discharged, folks.

    1. Part of my training was at a short wave broadcasting site (lots of 100 kW transmitters, many more huge antenna arrays). Very early on I was given a couple of rags and a bottle of denatured alcohol and told to go and clean the high voltage switching contacts. The space was cramped and hot and I was terrified by the capacitor voltage ratings and the size of the insulation needed. Touching the first contact was a real test of willpower. Got them all wiped (they didn’t really need cleaning) and got out with a profound respect for safety interlock systems. Designers, the real reason you have to be serious with safety interlocks is that you will kill someone if you skimp the design.

        1. Oh yes indeed!

          We were refitting an old fashioned barbers shop in London during the late ’70s. The ‘standard’ procedure was to cut the old cable off at any walls, partitions, etc. and pull it clear.

          I checked with my ‘colleague’ (I called him something rather different afterwards) that he had removed the fuse before cutting the main 30A cable where it came through the wall.

          There was an almighty great bang causing me to fall off the step-stool I was using and land on my arse.

          I wasn’t injured, but my very expensive, heavy duty, 2KV rated insulated handle wire cutters had a ruddy great gouge in the jaws.

          On inspecting the fuse box myself I found that my ‘colleague’ had removed the HOUSE ring mains fuse and not the SHOP ring mains fuse.

          It wasn’t entirely his fault of course, I should have checked the power was actually off. However after an experience of that sort, a certain amount of intemperate language is to be expected.

        2. I did of course follow all the safety procedures but when you have crawled into the middle of a transmitter cabinet you are really dependant on the safety interlock system.

  3. Whoa – A young person is explaining vintage technology in detail instead of spending all of his time with his head-down perpetually buried in mobile phone Social Media Crap? Unheard of!

    Don’t let this video fall into the hands of his peers, who have been indoctrinated against this behavior in the corrupt public school system. Otherwise he’ll never get some.

  4. My company used to share a tower and in addition to our stack of transmitters I got to see a huge old analog AM transmitter about 4-8 times bigger than the one in this video though it wasn’t ours so I never got to look inside… I’ve seen inside our little 2 and 4u tx’s before and they are pretty neat… I’ve also seen them bring in some digital broadcasting stuff which has much more fun displays and stuff but aren’t as cool.

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