The Connecticut Kilowatt

[W2NBC]

Hey Folks,

Just when the genuine old buzzard homebrew transmitters are mostly found as rusted out heaps at landfills, I was tipped off to a great find within comfortable driving distance.. YEAH!!
The gentleman has not operated this transmitter in over 52 years, but I bought it (for an extremely reasonable price, unseen)..

Here is the layout:
The RF deck (3ft tall, separate rack) is based from the template of the "Connecticut Kilowatt" (August 1954 QST)..  A pair of 4-250A's.. and was described as looking VERY much like the photo in the article, and "close" to the schematic..

http://www.scribd.com/fullscreen/39636431?access_key=key-q13ul58a6s1vgg43o6v

The interesting thing is the power supply-modulator (also in a 3 ft high rack). It uses a pair of (get this) 849's in the modulator! These tubes were last produced around 1940.. Just to give a scale of these tubes, another pic below shows the size..

The power supply runs at 3200 volts so this is close to a true kilowatt in the traditional sense.. The Bartlesville Transmitter used a pair in the modulator..

http://amfone.net/ECSound/BartlesvilleTX/bvilletx.htm

Here is the question! The 849 tube is fairly hard to find at price less than filling my oil tank.. 810's would be a great choice, (different filament, bias)..I would just love to restore and keep this thing original.. So, experiences with 849's anyone?? Thoughts..

 Yours in Amplitude,
      Jeff

[KM1H]

The 849 has a reputation for going gassy but if they test out OK try running them. Nothing wrong with 810's either and with 4-400's in the RF deck you can really push the KW level, they plug right in.

1954 must have been a good year, I picked up the Jan QST cover rig in CT a few years ago, a 813 transmitter.

Carl

[KE6DF]

A few 849's show up on epay each year. Also, a few 204a's which are similar and (I think) use the same socket.

No telling if tubes you buy on epay are any good, though.

[W2VW]

I have what might be a good pair of 810s I'm never going to use. Just say the word.

[W2NBC]

Thanks for the info guys.. Interesting on the "gassy" reputation for 849's, and the 204A is a VERY similar tube.. and thanks for the offer, Dave!

 All large triodes have hit the audiophools Xmas want list.. An example of the 849 now on e-pay:

 http://www.ebay.com/itm/GIANT-POWER-TRANSMITTER-TUBE-TYPE-U-S-N-CWL-849-CWL-849-WESTINGHOUSE-NOS-NIB-/280967936320?pt=US_Ham_Radio_Transmitters&hash=item416afe7940

The point here, is just like the preservation of Broadcast transmitters from the the "Radio Days", these homebrew pieces deserve restoration and USE, with a place of honor in this shack..

..and a promise I made to this old-school gentleman when his work rides away after 50 years..

[W1TAG]

Jeff,

The 849 brings back memories. RCA used two of them as modulators (modulating two pairs of 204A's in PP) in the 1-D, their first air-cooled 1KW broadcast rig. The station I worked for some years ago had purchased a 1-D in 1934, and when I started there in 1970, the rig was still in place as part of what was called a 5-D-1. The original exciter section of the 1-D drove a 5KW amp (892R modulated by two 891R's). The 1KW amp described above was not used, and had seen no air time since the early '60s. One night in the late '70's, we fired the thing up after carefully working out what switches and jumpers needed to be thrown. It worked right off the bat, making the full 1KW with 100% modulation. The 1-D had a built-in oscilloscope at the top of the cabinet, and even THAT worked.

Sadly, the rig had to be dismantled shortly thereafter to make room for new gear. We originally wanted to move and save it, but the old lead-covered wire was in tough shape, so we had to pull it apart. But last I knew, there were still some 849's in the building, so if you come up with a need, let me know, and I'll see if they would part with any. Not my current employer, but we're on good terms...

Good luck with the rig.

John, W1TAG

[KB5MD]

I would love to find a  National MB40-L tuning unit like the one used in the circuit or a reasonable facsimile.

[KE6DF]

There is an 849 on ebay right now. Claims to be NOS.


http://www.ebay.com/itm/GIANT-POWER-TRANSMITTER-TUBE-TYPE-U-S-N-CWL-849-CWL-849-WESTINGHOUSE-NOS-NIB-/280967936320?pt=US_Ham_Radio_Transmitters&hash=item416afe7940

[Steve - K4HX]

If you can get in contact with W2ZM, do so. IIRC he ran a rig with 849s in the recent past.

[W2NBC]

Thanks Steve for the tip.. Yes, Bob W2ZM has a tremendous amount of interesting transmitters, including the Heising modulated one using an 849. Pic below.. and thanks to John, W1TAG with a most interesting and helpful post.. I will be posting pics of the Conn. Kilowatt when it gets here, and thanks all for the help on the 849's!

[w1vtp]

Thanks Steve for the tip.. Yes, Bob W2ZM has a tremendous amount of interesting transmitters, including the Heising modulated one using an 849. Pic below.. and thanks to John, W1TAG with a most interesting and helpful post.. I will be posting pics of the Conn. Kilowatt when it gets here, and thanks all for the help on the 849's!

So that's the precursor of the QIX clip-lead technology ?

Al

[W3GMS]

Thanks Steve for the tip.. Yes, Bob W2ZM has a tremendous amount of interesting transmitters, including the Heising modulated one using an 849. Pic below.. and thanks to John, W1TAG with a most interesting and helpful post.. I will be posting pics of the Conn. Kilowatt when it gets here, and thanks all for the help on the 849's!

I worked Bob, 2ZM with that rig many times.  Nobody but Bob would try to modulate a self excited Hartley Oscillator!  He kept the modulation percentage down around 60% and it sounded very good.  I have lots of audio recording of that rig.  It was pretty darn stable and very little FM'ing with the lash-up.  I believe he had it working pretty darn good up through 40 meters!  I went up for a visit to Bob's and saw it and also took some pictures of it. 

Joe, W3GMS

[Todd, KA1KAQ]

Congrats on the find, Jeff! You just gotta love that old gear and the monster tubes they had back then. I've got a couple 849s here, both are toast though. Was in touch with a fellow a couple years back who wanted to sell me 4 of them but they were pulls and he wanted BIG dollars for them. I passed since I'd prefer building 861 x 204A. The tube sockets are far easier to build than find.

Looking forward to hearing it pounding into NC in the future.

[W2NBC]

The Connecticut Kilowatt takes a foggy vintage shape through a slide that the owner sent me,  circa 1950's at his operating position.. I had no way of viewing slides anymore, so shot some light through the transparency.. 4 Simpson meters, peek-through window at the 4-250's, and SX-71.. Nice!

[KL7OF]

Very cool rig...If it will run with the 849s you have, please run it that way...those old tubes need to be run...they don't do any good on the shelf...I run some unobtainium tubes here and will continue to do so until I run out......Great find..put it on the air!