>I am planning to rebuild my old amp (4 - 811A's in G-G) and replace the
>entire deck with a single 4PR1000.
>I have the Socket, HV transformer, caps, roller inductor and the rest. I
>still need the Filiment Xfrmr though.
>
>Has anyone built an amp using one of these tubes? If so, how did it fly?
>Any glitches with the tube or other annoyances that are noteworthy?
Hi Bob,
I've got a 4-1000A amp that I am in the middle of right now. The 4PR1000
is the same tube rated for pulsed service. It's quite heavy duty from
what I understand and can really take abuse. So you've got a good tube.
The filament needs around 20 amps at 7.5 volts. My xformer is pretty
good size (about 5x5x7). and weighs about 10 pounds.
The 4-1000A is a tough tube. Rich (AG6K) is right on about the pesky
screen resonance. My first try at the amp using someone elses design
(bought the amp from an estate sale) resulted in the amp oscillating on
10 meters. I also had problems on 15 meters too.
The tube loves high voltage for good gain. I use right around 6 KV and
get out about 1300 Watts with 100 Watts drive (GG). If you can drive it
with more power, you can use a lower anode voltage.
So, it is a squirley tube but a good one once you get the bugs worked
out. The other thing people have said is that the tube tends to have
distortion/IMD problems without a screen voltage. I have not verified
this, but some pretty reliable people tell me this. I have also seen an
older design article that did include a negative supply for the screen.
I think you'll get a little bit better gain that way as well.
I hope this helps, if you need any more info, let me know.
73,
Jon
KE9NA
--------------------------------------------------------------------------
Jon Ogden
jono@enteract.com
www.qsl.net/ke9na
"A life lived in fear is a life half lived."
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