[Amps] Triode Amps

[John Lyles]

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.

John

K5PRO


> Message: 1
> Date: Mon, 6 Dec 2021 05:00:41 -0600
> From: Rob Atkinson <ranchorobbo at gmail.com>
> To: "amps at contesting.com" <amps at contesting.com>
> Subject: Re: [Amps] Triode Amps
> Message-ID:
> 	<CALWD7Z6zCfsgWs4j2Zt5EzrUsrwiMLKUuay9yTDuKbm1Hm-A-w at mail.gmail.com>
> 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.
>
> 73
> Rob
> K5UJ