[Amps] SB-230 Power Question

[n8de at thepoint.net]

Paul,

I agree, though I didn't notice that earlier.

73
Don
N8DE


Quoting Paul Decker <kg7hf at 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 at contesting.com"
> Subject: [Amps] SB-230 Power Question
> Message-ID:
> 	<1363679742.11720.YahooMailNeo at 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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