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Guillermo, Those tubes are rebrands so it's untelling who actually made them. If it was GE years ago, look to see if there is a series of little dots etched into the glass where the tube number is at.

Hello, I want to ask about something that happened this week with the output tubes in a Drake TR-4 I was committed to repair. It has three 6JB6 in parallel to achieve 200..220 watts out at 80, less at

Bonner" <rbonner@...> wrote: ways a bunch Correct, but it takes a much thinner piece of steel to equal the same strength of aluminum so they equal out close to the same. Generally, 20 gage steel is

Sorry, I need to be more specific... 3CX1200D7 (YU121) denny

Flat and simple, aluminum is lighter. A fully loaded amplifier ways a bunch even with Aluminum used the construction. You could get by with making the top socket level plate copper. Stainless and

All, Here's my thoughts on the naming conventions when using the term ground in a tube circuit. Ground, or chassis ground is the ground that goes back to the power source. The chassis is most always

The way they're building most amps these days is to use a clam shell type cabinet made of aluminum or like to C's placed together at 90 degree angles. The actual tube chassis is a box made with

Dear Bill, You left yourself wide open for this one: "Why not?' Sorry, Bill. I hadda get that one out. Ooooooooo. However, on a less serious note, let's consider the arrangement of the stuff. Remember

Also YU1AW does it in some of his designs. Collins does the same in the 208U (4X10000) and 204C-1 (4CX5000) I have a 3 x 4CX250B amp for 144 MHz designed like that, has given me very good service for

I used to own a pile of Collins 208U's they used the 4X5 with a grounded screen configuration, the 1200V "screen" now actually a cathode supply pushing the cathode negative and a 4000V plate supply. I

Peter, Do you have a 1:2 BB transformer at the input of the 4CX3000A? Frank wa1gfz 4CX3000A driver also (GG) Peter Voelpel <df3kv@...> wrote: No, screen voltage is supplied between cathode

Hi Will, I wrote that the cathode is floating below ground potential. Steel chassis I would never use in a high power amplifier at places where RF flows and no soldering at all. Just copper and

Will, All manufactors of broadcast and TV transmitters here call it grounded cathode when it is at chassis ground. Main reason doing so is to get rid of bypassing problems with the screen. Another

wrote: I know this, see my last post. Grounded to chassis ground with the screen? The only way I can see doing it is floating the cathode from chassis ground where the screen is tied to. There's no

If anybody has heat sinks made of diamonds, my wife has em... She'd just carrys em around and waves em... She hears it every night, will you go home with me? I have something big I wanna show you? She

Tom, That's exactly the only way I could figure they done it, and to me that's not what I'd call a grounded screen. To me, I call a grounded screen one in which the screen would be tied to the cathode

Hi Will, All electrode voltages of a tube are referenced to the cathode. If the cathode is directly grounded at the socket, screen voltage is supplied between cathode and ground (negative at the

Peter, If it is, then you can't really call the screen a grounded screen, it isn't. It's being ran with a positive screen voltage the way it should be. This being whether it comes from a seperate

ORIGINAL MESSAGE: wrote: ------------ REPLY FOLLOWS ------------ In light of your statements above, I have two questions: 1. Why is diamond, which is less dense than copper, a better heat conductor?

Yes, that is exactly what I did, + bias, - screen and - HT all tied to the centre tab / cathode and bypassed with a couple of capacitors to ground. The other amp is the YL1056 on 2m, where the screen