>
>A problem for all the experts-
>I Built a 3-1000Z monoband amp for 10 meters. I Sowly Variaced it up and it
>seems ok at 1500volts. Put 3KV on it and it will make a few watts of power
>without even putting RF to it. I heard a small RF type arc- kind of like
>slight arcing in an air variable, (I have a vaccum cap) the tube glowed red
>and I quickly unkeyed it. I turned the load and tune caps a bit, tried it
>again- it was quiet for about 2 or 3 seconds- then it did it again. I have a
>similar homebrew grounded grid 4-1000A amp and never had a problem- it
>worked
>great the first time I fired it up! I built the 10 meter mono-bander because
>I cant get the 4-1000A amp to work on to good on ten- but it works great on
>the other bands. Any suggestions??
3-1000Zs have much feedback capacitance - which is why they oscillaate.
I would try decreasing the RL of the parasitic oscillation suppressor.
>Keep in mind- I have yet to even hook a
>rig to this- just a dummy load- I variaced it up, saw idling current, and it
>started to run away.
good luck, Jim
>
- Rich..., 805.386.3734, www.vcnet.com/measures.
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