The AM Forum

I'm putting the finishing touches on a parallel 807 amp. I have 5 x 5933 tubes I'd like to use but have no idea how good they are. I have a small tester but it won't handle this particular tube. I'm in north-central Wisconsin and could either bring them or ship them to you. Then again, is there an alternative way to check them out? It seems if I use one tube at a time and tune the amp, I can find out how it operates and then match a pair with similar meter readings. Any suggestions??!?

Mike
W9ZSL

Mike,

Best way to test them is the way you said, one at a time in the amp you're building.

Fred

That's what I'm thinking. This amp is from the '57 ARRL Handbook and should do 120 watts AM. It could also be used as a Novice rig by removing one of the tubes.

With a VOM you can check the filament continuity and for shorts between elements. When testing in the rig, along with the usual measurements, you can look at off-resonance plate current — briefly. Shouldn't take too long to sort them out. Just make sure the HV is off between iterations.


A pair of 807W/5933 is rated 120W input ICAS on AM. Don't expect much more than 85W output. In 1957 a novice may have had to pull out a tube (75W input limit) but not any more (200W output limit).

BTW, are you going to bias the amp with a 67.5V battery as shown in the 1957 handbook? ;)

No battery. Power supply has a full-wave bridge adjustable bias supply. I get up to 135 volts out. It's on the far left. Built this by the book and I'll have 600 volts under load. I finished the amp today but haven't tested it. The exciter is a 6AG7 / 6L6 from the '49 West Coast Handbook. Everything is set up for 80 meters but will eventually be 80 / 40. I'll have some pics of the amp in a bit. I'll probably modulate with a pair of 6146s with an ART-13 iron. I have a separate 600 volt supply for that.

Nice looking... old school above, modern under the hood. 6146's will modulate it with room to spare. So will another pair of those 807W/5933's if you have enough of them that turn out to be good. That would be cool. 8)

Good looking chassis and layout.  8)

I can test them for you (I am over here in Ioway and have two Hickok tube testers) and

I have had no problems shipping tubes with the indirectly heated hot cathodes.

It's the single filament tungsten tubes that can be damaged in shipment due to shock loads and vibration unless very well packed.

Phil - AC0OB

Hi Phil!
Sounds good. It will take me a few days to get things together. How much do you want to do the job? I'll probably ship flat-rate priority and with luck you can use the same box to ship them back. There will be 5 x 5933s and a pair of 807s which I think are good.  You can contact me direct at W9ZSL@yahoo.com so I can get your QTH. Took some shots of the deck this morning. The chassis and front panel were purchased from another member a couple years ago. He was building a 4-125A 80 meter amp. I salvaged it and decided to build this unit. Probably could have made it a bit more compact but I made do with what was on hand. Eventually, when I add a 40 meter antenna, I'll modify this with a band switch. Did a lot of HB before my heart problems. This is just a warm-up for a bigger amp...practice as it were!

Mike Kuehl
W9ZSL

Love that peek-a-boo window!

I don't want anything for testing Mike but you pay shipping both ways.

My address is current in the FCC database.

http://wireless2.fcc.gov/UlsApp/UlsSearch/license.jsp?licKey=3084034

Please pack them well  8)

Phil  - AC0OB

QSL. Will do! MK

The window came with the panel and chassis.