[Amps] SB-200

Carl km1h at jeremy.mv.com
Thu Feb 9 07:04:00 PST 2012


The first thing Id check is for an open 33 Ohm grid resistor and cracked 
200pf mica cap at the sockets. You could be running on just one tube.

Carl
KM1H


----- Original Message ----- 
From: "Tom Osborne" <w7why at frontier.com>
To: <amps at contesting.com>
Sent: Wednesday, February 08, 2012 9:33 PM
Subject: [Amps] SB-200


> Hi All.
>
> I have a SB-200 and it developed a problem in the last week or so.
>
> When tuning up on 40, the Load cap is all the way meshed and the Tune cap 
> is about 50% meshed.  It puts out about 400 watts on 40.  On 40, the input 
> SWR is 1:1.
>
> In 80 the Load cap is all the way meshed.  It puts out about 200 watts. 
> The input SWR is 1:1.
>
> I checked to make sure the 2 sections of the Load cap were soldered 
> together OK and they are.  I disconnected the cap that is switched in on 
> 80 and replaced it with another one and still doing the same thing.
>
> If the tubes are going soft, will it affect the tuning like that?  Seems 
> like I've replaced the tubes before but never had the problem of the Load 
> cap being all the way meshed to load on 40.  Thanks and 73
> Tom W7WHY
>
>
>
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