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[Amps] Help needed on 4CX250 AMP

To: <amps@contesting.com>
Subject: [Amps] Help needed on 4CX250 AMP
From: sandeep1@softhome.net (Sandeep)
Date: Sat, 14 Dec 2002 08:52:21 +0530
Friends
            I am trying to put a old Marine TX on ham band. I was able =
to rig up the Screen Power supply with help from this group. I even got =
some components from a generous member.
    Now I need some more help. First the details of rig. It uses 4 no. =
4CX250B valves in final. The output circuit is Pi-L with rollor =
inductors as inductive component and the capistors are fixed, switched =
by a band switch. HT is 2000 V , Screen 350 V regulated.
    I was trying the amp on 20 m band. There is NO capacitor on tuning =
side on this band and a 100 pf on loading. I was able to get only about =
800W out with 600 Ma plate current . Only a few turns on the loading =
inductor comes into circuit rest are shorted. If I further try to =
increase loading by turning inductor, it arcs badly. Increasing drive =
level does'nt help.The TX was supposed to deliver 1400W with 1 amp plate =
current.
Please suggest what should be done now and also excuse me if i m putting =
some very stupid questions, this being my first amp project.
I can even provide the scanned copyof diagram if that helps.
73s
Sandeep
VU2BX


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