rough and not pretty Maco 750 on the bench
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- Опубликовано: 27 авг 2024
- I got this as a junker mostly to get the tubes. However, it was another bad packed disaster. Some of the tubes were broken. The tubes were 21JS6's anyway. Someone had modded the filament transformer so instead of the 12V for M-2057 tubes, or 6v for 6lf6 tubes, someone put in a 23v filament transformer which will run 21 and 23 v filament tubes. Since some were broken and some were bad, I got a few replacements off Ebay but now I have a mis-mash of good, fair, used, new, 21v, 23v different brand of tubes. Oh well, maybe in the future I will look into retubing it with all matching good tubes.
When it came to me, not only were some of the tubes busted, the HV power supply was a total train wreck. The cap bank and diode bank were so bad, I just replaced them both. 330uf snap caps replaced the original beat up 220uf cans and the 1 amp diodes were replaced with heavy duty 6 amps. Then the bad tubes were replaced with mis matchers but it all works. Doesn't do max capable watts with the tube situation, but 400 solid dead key watts and 600 watts peak and bad. Probably would hit 1k peak with a good set of matched tubes. Ok, back to the Lions game for me, LOL.
we use to take a maco 750 and convert them to 6146w amp 8 tubes
I like 6146's and they are cheap. Good job.
10 meters opened up yesterday and there were some really strange signals that I attributed to over-the-horizon radars. I worked a bunch of European stations on my 430, but I need to see if I can limit the output to 10 watts output into the MaCo 300.
Yep, they like low drive.
I saw one of those in worse shape mounted in the trunk of a car that was running off a homemade inverter that looked even worse. They wanted me to work on it. I just laughed and told them to go get a ham license.
Been there, done that.
My brother had 2 brand new maco 750s back the 70s....he talked round the world.
Maco's were beasts!
I wonder why there are different filament voltages. Just makes it more difficult and expensive to stock parts. Time for those "Honey Doos"? Oh dinner. Bon appetit. Thanks for the video Doc.
Back in the day, certain tube prices and availability became a problem. Hence, they would switch to something cheaper and more common. I went into the Army in 1980 and 6lq6's were plentiful and cheap. I got out and got back into CB'ing in 1986 and 6LQ6 tubes were now hard to find and expensive. The CB boom with millions of CB'ers and many running amps, ran up the market of sweep tubes. (TV tubes)
@@tramdr
Makes sense. A friend who recently closed his bicycle shop after many years was asked "are all the parts on bicycles interchangeable and the same", he laughed and said "I wish".
@Civility went out the window The only problem with powering the heaters directly from the line is that if one of the tubes develops a heater to cathode short you can have 120 volts on the amplifier input circuit when it keys up. Nothing good can come of this!
Tramdr, great videos! I have a old tube type radio i would like for you to take a look at and maybe refresh. How can I reach you?
Sorry, I don't do others.
I have a Telestar Magnum 4cx250b x 2
I need a foot petal and anode caps. Thanks
Sorry, I don't do others.
Do you still have it
I think so.
@@tramdr how can I contact you about getting it
Tramdr at Yahoo.com
Yo, Send me a mailing address, And I ll send you a can of electronics corrosion blocker. I got the old school stuff. 10-4
Contact me at Tramdr@yahoo.com