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Hal, Yes, one of concerns is "committing" to a tube that dries up by way of availability.? That's why the GS35 and Gu43b are on my radar,as they seem so plentiful.? If i do get an amplifier up and

Was discussed some years ago on the amps reflector: <http://lists.contesting.com/_amps/2007-10/msg00036.html> Its a low ? generator tube with poor iMD and high drive requirements. 73 Peter, DJ7WW

Dear Des, Some years ago I invested money into whar was then a seemingly up-and-coming amplifier that used a GU-78b. The first thing I did when setting the amplifier up was to seek out a spare tube.

Jim, I found a reference on the net to someone who has build an amplifier around the GU5b some time agai and he stated gain was low and required 200w drive to maximise output. Here is a link to the

How do u now the GU5B? only has 10 db of gain ??

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.?