The 4-400 in GG have less gain than a 3-500 and a pair is usually good for
1000W in a full GG SB-220 thru 10M at 100W drive unless they are tired
pulls. I converted an ISM amp with a pair of them to 6M many years ago and
after converting the PS to a big cap and tossing the choke they easily ran
1500W at 3400V and 120W drive from my amp bench transverter.
Carl
KM1H
--------------------------------------------------
From: "Larry" <larry@w7iuv.com>
Sent: Wednesday, January 28, 2015 11:12 AM
To: "Manfred Mornhinweg" <manfred@ludens.cl>; <amps@contesting.com>
Subject: Re: [Amps] What tube?
AS far as I know, there is only one tube(s) that meet your requirements; a
pair of 3-500Zs.
If you drop the "instant-on" requirement, there are quite a few other
possibilities.
One other possibility if you can handle it might be 2X or 3X triode
connected 4-400As. I've not been able to reliably get 1500 out on all the
HF bands with a pair, but three in parallel makes it easy. See my web page
for a 3 x 4-400A 40 meter monobander.
73,
Larry - W7IUV / WH2XGP
On 28-Jan-15 6:00 AM, Manfred Mornhinweg wrote:
A question to all those of you who have used many different tubes:
What tube(s) would you recommend for a legal limit HF amplifier, to get
as close as possible to the following goals:
- Class AB2 operation at high efficiency, low idling power, at
acceptable IMD (doesn't need to be brilliant).
- Ideally grounded grid triode, but a tetrode with screen supply is
acceptable if a GG triode won't do it.
- Instant-on filament, or at least quick heating (no more than 10
seconds).
- Easy cooling requirements, so that a low noise fan or blower can be
used. Maybe conduction cooled or water cooled.
- Available and reasonably priced.
I know I'm asking to much, but I would like to analize the best options
out there!
Manfred
========================
Visit my hobby homepage!
http://ludens.cl
========================
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