Date: Tue, 6 Nov 2018 21:23:38 +1030
From: "Leigh Turner" <invertech@frontierisp.net.au>
To: "'Steve Bookout'" <steve@nr4m.com>
Cc: "'AMPS'" <amps@contesting.com>
Subject: Re: [Amps] power limiting in 8410 amps?
<Yes I concur with this suggestion Steve.
<With only 200 Volts on the screen in AB1 linear mode the 4CX1500B tubes are
<likely being starved and held back like variously reported amongst 8410 amp
<users. The screen voltage probably ought to be up around 275 to 300 Volts to
<ensure unconstrained power output to 1500W+ without significant gain
<compression.
<Leigh
<VK5KLT
## What is the IMD on this amp, when driven to 1.5 kw pep out...
with a 2 tone signal ?? It cant be good.
## Baffles me why Alpha even used a pair of 4CX-1500Bs.
They should have stuck with a single 8877.... like their auto tune 9500 amp.
IE: a manual tune version of the Alpha 9500.
## By using 2 x 4CX-1500Bs.. they have just complicated it needlessly.
2 sockets, 2 tubes, 2 chimneys, 2 anode connectors, 2 parasitic
suppressors,
regulated screen supply, bias supply, etc, etc. Talk about making a simple
manual tune amp into an expensive exercise.
## A single 8877 would have easily sufficed, reliable, proven, etc.
At least OM power got it right with their OM-4000.. which uses the
chinese version of the tube.
Jim VE7RF
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