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Let me update that, I've seen a full amp of plate current draw from two 3-500ZGs at 4050v under load (4500v idle) and he's getting about 70% efficiency from a very well built custom mono-band amp for 40m.
He drives it with the 200w version FT-1000 MkV and regularly hits 2800w pep on his Bird pep meter. He's still running the same set of tubes he's had for the last 4 years without any loss in output.
He cools them VERY well by pumping cool air into the RF deck from a large outdoor squirrel cage fan and exhausts back outside.
The RF deck cooling is sealed off from the room so it's barely audible and you can't hear any fan noise in his background, but he is also running a downward expander.
I'm accumulating parts to build one like it, though a set of 4-1000s sure is tempting, they're just so darn big and hard to find.

<blockquote data-quote="Needle Bender" data-source="post: 404652" data-attributes="member: 13339">Let me update that, I&#039;ve seen a full amp of plate current draw from two 3-500ZGs at 4050v under load (4500v idle) and he&#039;s getting about 70% efficiency from a very well built custom mono-band amp for 40m.&nbsp;He drives it with the 200w version FT-1000 MkV and regularly hits 2800w pep on his Bird pep meter. He&#039;s still running the same set of tubes he&#039;s had for the last 4 years without any loss in output.&nbsp;He cools them VERY well by pumping cool air into the RF deck from a large outdoor squirrel cage fan and exhausts back outside.&nbsp;The RF deck cooling is sealed off from the room so it&#039;s barely audible and you can&#039;t hear any fan noise in his background, but he is also running a downward expander.&nbsp;I&#039;m accumulating parts to build one like it, though a set of 4-1000s sure is tempting, they&#039;re just so darn big and hard to find.</blockquote>

[QUOTE="Needle Bender, post: 404652, member: 13339"] Let me update that, I've seen a full amp of plate current draw from two 3-500ZGs at 4050v under load (4500v idle) and he's getting about 70% efficiency from a very well built custom mono-band amp for 40m. He drives it with the 200w version FT-1000 MkV and regularly hits 2800w pep on his Bird pep meter. He's still running the same set of tubes he's had for the last 4 years without any loss in output. He cools them VERY well by pumping cool air into the RF deck from a large outdoor squirrel cage fan and exhausts back outside. The RF deck cooling is sealed off from the room so it's barely audible and you can't hear any fan noise in his background, but he is also running a downward expander. I'm accumulating parts to build one like it, though a set of 4-1000s sure is tempting, they're just so darn big and hard to find. [/QUOTE]

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