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[Amps] Triode Amps

Subject: [Amps] Triode Amps
From: John Lyles <>
Date: Tue, 7 Dec 2021 01:33:23 -0700
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I didn't know W2ZN was SK. I wonder what became of his Power Pebble rig? I have a Continental 314R1 Power Pebble that is still on 1290 KHz, hasn't converted up to HF. It took a bit of restoration to get it working reliably again, so I never got around to the next step. It is a nice rig, three 3-500Z in the window. One time the switch tube got stuck on and turned bright red, almost white before I tripped the breaker. I think that tube was ruined. Its got a wicked 8500 volt power supply with a big capacitor.



Message: 1
Date: Mon, 6 Dec 2021 05:00:41 -0600
From: Rob Atkinson <>
To: "" <>
Subject: Re: [Amps] Triode Amps
Content-Type: text/plain; charset="UTF-8"

My guess is that the hardware to withstand higher B+ Is hard to come by.
That's not a problem.  Plenty of parts out there that can work.  Lots
of AM rigs swing up to at least 4 KV DC on positive modulation.  Then
the peak of each RF cycle goes higher.  A couple guys, one now SK (Bob
W2ZN) run or used to run Continental power pebbles on 160.  That was a
PWM rig that ran a pair of 3-500s in the final with a third one used
as the switch.  8 KV from the h.v. supply.

No, the problem isn't h.v. parts; it's stabilizing the PA so it
doesn't take off when the anode v. gets up over 4 KV.  Cathode driven
is easier, one reason for its popularity, but even a g.g. 4-1000 can
get squirrely on the high bands with 5 or 6 KV on the plate.

BTW a pair of 3-500s will produce 1500 w. in g.g. cathode driven
linear service but it takes more drive than a lot of hams can produce,
around 130 watts.  That's partly because modern amplifiers don't use
plug in coils for band changes which optimize the Q for each band.
The 3-1000 is a better choice because it's rated for higher plate v.
Harris and BTI used it.

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