Transmitting tube amps

[THD+N]

Anybody here dabble in the big tube amps? 211 or 845?

 

[Skywavebe]

I have had to work on some transmitters in my days in radio. You said transmitter Tube amps didn't you?
These amps used voltages up to 10,000 and put out anywhere from 8KW on the Hancock to 34KW on the ground for a
ERP of 100KW at my last job. I guess the 50 KW solid state amp at ESPN 1000 did not count as it has no tubes in it.
These are for RF transmission in the FM band. You can't make any mistakes with 9KV at 3 Amps so I am still here.
How about a 450Amp filament current- you should see those wires.
Now I am sticking with those small RF devices known as Bias Oscillators- they are not so dangerous.

 

[laatsch55]

WHOA!!!! Didn't realize things were like that. WOW!!

 

[mlucitt]

I wanted to build an amp with a pair of 4-400A Eimac tubes but the parts list started to get expensive very quickly...

 

[THD+N]

I have a pair of mono-block 211 amps I built about 12 years ago (original design by me). Class A, single-ended, no global negative feedback. Super old school with xenon rectifier power supply (recently took out the 866A rectifiers) and custom wound output transformers.

14 Watts each of smooth sound.

 

[mlucitt]

Yeah, so the transformers for the design I was looking at weigh 90 lbs and I need two of them. I think the amp with the twin 3-500Z tubes, sockets, chimneys, capacitors, insulators, wire, and chassis would be close to 140 lbs... for one channel. So, I think I'm sticking with transistors for now.

 

[johnelderrobison]

I dabbled in lots of tube amps, years ago. The transmitting tube amp I liked best was the Ampeg SVT, which got 300W rms out of 6146 transmitting tubes. Later SVT models switched to the more common 6550 audio tubes but the 6146 design delivered more power. Bogen got 100-some watts from 8417 tubes in their PA amplifiers of that era.

If I wanted that sound today I think I would get it with a mosfet design. The most prominent characteristic of the tube amps - in my opinion - is the shaping that takes place in the output transformer, and the absence of strong damping as found in todays direct coupled tube amps. That could be replicated - as MacIntosh did - with a transformer coupled solid state amplifier design.

Maybe one day I will design amplifiers again.

 

[mlucitt]

John, glad to see you here! Yes, I was a big fan of the SVT and those six power output tubes. I did some amplifier work for the bass player of the band Slaughter. The bass player was Dana Strum, but when we were both attending Chatsworth High School in 1974, his name was Dana Strumwasser. He used a Gibson slot-head EB-0L (long scale) and I later bought the same bass and now my nephew, Eddie Lucitt is playing that bass in a band called Fools And Sages here:
https://www.facebook.com/photo.php?...80880780.19746.169454883179810&type=1&theater