[Amps] SB-230 Power Question

[Paul Decker]

I admit, I don't know anything about the SB-230, but 100W drive seems excessive for an 8875/8874, is there some sort of attenuation for the input?  

My 432 MHz amp using a single 8874 tube takes 25 drive to produce 500W out.   

Paul,
KG7HF






Date: Tue, 19 Mar 2013 00:55:42 -0700 (PDT)
From: K4MT 
To: "amps at contesting.com" 
Subject: [Amps] SB-230 Power Question
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I recently acquired a SB-230 thinking the tube was probably bad with an idea of doing a GI7B project. To my surprise the amp puts out 650 watts plus on my peak reading wattmeter on SSB 80/40 Meters with 100 W drive..

On the bands from 20 and up the power output drops. ?20 Meters is about 550, 15 meters about 350-400 and I ?have not tried 10m. ?

I recapped PS, rebuilt tube grid circuit and repaired some bad soldering and out of tolerance parts, replaced grid bypass capacitors, removed entire tank circuit and band switch. Cleaned bandswitch and cleaned/resoldered all connections.

Still power on higher bands drop as above.

Any experts on this amp out there who might have an idea what might be going on. Is this a sign of a weak tube? ?Since I get so much power output on 80/40M I would think the tube must still have some life in it.