SB-201

[Kenneth G. Gordon]

On 23 May 2008 at 10:49, Terry England wrote:

> Hello all i just got me a SB-201 with the 10m mod done but it has a
> problam. It works fine on 80m 500-600 watts out on keydown

Not bad, but not perfect either. If all is working exactly correctly, with 
good finals, you should get 750 watts output.

> but on 40m
> 20m it does nothing out and the plate voltage is full scale.

Do you mean plate CURRENT? If you really mean VOLTAGE, and not 
plate current, then it is most likely that the HV metering resistors are 
WAAAAAY out of tolerance.  This isn't unusual with the SB-200/201.

If you mean CURRENT, then it is possible that there is a wiring error in 
the input circuitry such that it completely removes the grids from ground.

> But not
> sure if meter is working right either it only shows 300 volts on the
> HV scale which i know is wrong.

Metering resistors shot. Change them for new ones with higher wattage 
rating.

> I never tried it on 15m or 10m figured
> it also never worked there since the other bands don't work. Any ideas
> on where to start looking to get it back up and working like it
> should?

First, make certain your metering circuits, especially HV, are working 
correctly.

Then you should look very carefully at the input circuitry. I'll bet there is 
one or more errors there.

Ken Gordon W7EKB

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