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Guys, Thanks all for your responses, lots of food for thought. I think the GU5b will not do what I need/want. It will need 100w drive for about 1kw output, so not enough gain.? The gs35b suggested

Is the GU5B a high mu triode ???? ?( MU at least 130 or higher).? If not, you are DOA right there.? ? Low mu triodes can't be used in GG (cathode driven service).? Reason is, they will draw

I would use one and keep the other as a spare, in terms of heat, just the 250W of filament power each will keep the shack warm enough in winter! If you directly ground the grid and have the input tune

Love it! I run a YC156 in my homebrew amp.? It's way way way overkill but at 4.3KV, it runs limit power without trouble and I don't have to worry about breaking the tube.? I've got a number of

Hi Jeff! Merry Christmas. I can just imagine two (2), 3CX15,000A7's, in Push-Pull, Modulated with two (2), 3CX15,000A7's. Riley Hollingsworth would personally lead the arrest, complete with Thompson

Hal, If you need a spare 15K, I've got a NIB one here that needs to find a new home. 73/jeff/ac0c alpha-charlie-zero-charlie www.ac0c.com

Have a good one, fellas. Best wishes for a happy and safe 2024. Mni 73, John VK6JX

Yes Jeff. "Took the words . . . . . ." 73, Alek VK6APK.

Steve, In calculating the Anode Iron requirement for Class AB1, the beast would weigh 565 pounds. (25 KVA). (3CX15,000A7) But that was 8 years ago, and now, and now: "Uh - Uh." Yon beasties are for

Here at my off-the-grid, solar-charged, battery-powered QTH, I'd need a submarine fulla good batteries just to run the heater on onna those, let alone leaving a brick on the key all day. ===8-O Steve,

Hullo Bill, So you're squeamish about 20 or 40 amps on the heaters, aye? Well, wait 'til ye graduate to Valves with Lifting Handles! Some of those babies need 165 amps to warm them up. Rich Measures

A single GS35b is a nice choice as well per your original power objectives.? And at 4.7KV it will have pretty nice efficiency.? I ran one here at 4.4KV for years.? Minimal heater current

20 + amps at 12 volts??? just to light up 1 tube ,,,,,???? 2 tubes would be 40+ AMPS !!!!! -- link to

Thanks everyone for replying. I live in Northern Ireland, call sign GI0UTE.? I'm not aware of any qro builders nearby.? I have ordered a few books as have been suggested and have stared reading some

Here, the paralleled pair of Jennings? RJ2B output vac relays are installed.....along with the 7-16 DIN output connector. Also installed is the 1/2" silver plated tubing coil, used for 20 + 15m.?

Stated he was in The UK. Mike

You don’t say where you are located or provide a call sign so those of us replying don’t know where you are for parts recommendations. The Eimac book “Care and feeding of power grid tubes”

I have found "Valve Amplifiers Explained" by John Fielding ZS5JF quite helpful, its published by the RSGB. Mike VK2AMF / G3XEF.

Dear Des, Welcome to the forum. You can't do too much better than the collection Of builders and thinkers hereon. In the amplifier schematic you posted I wonder If the Input Network Inductor is a

I would interject that The Radio Handbook, edited by Bill Orr and/or "Editors & Engineers", is generally much more informative than almost any of the ARRL handbooks for amplifier circuitry, in