I guess you guys didnt read the manual either (-;
The input is a bank of resistors to swamp power and the manual states 100W
drive but I dont run them that hard as the cooling is marginal without a fan
on the heatsink.
About 500W is safe and sane unless you have a lot of extra cash.
Carl
KM1H
----- Original Message -----
From: <n8de@thepoint.net>
To: "Paul Decker" <kg7hf@comcast.net>
Cc: <amps@contesting.com>
Sent: Tuesday, March 19, 2013 4:52 PM
Subject: Re: [Amps] SB-230 Power Question
Paul,
I agree, though I didn't notice that earlier.
73
Don
N8DE
Quoting Paul Decker <kg7hf@comcast.net>:
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@contesting.com"
Subject: [Amps] SB-230 Power Question
Message-ID:
<1363679742.11720.YahooMailNeo@web120205.mail.ne1.yahoo.com>
Content-Type: text/plain; charset=iso-8859-1
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.
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