SB-1000 Problem

[Bill Coleman]

On Nov 28, 2005, at 1:28 PM, Rinkie & Ron Pollack wrote:

> But first, I have to get the beast working!  I got it several  
> months ago,
> and it hasn't been used for about a year.  When I power up, with  
> the switch
> on standby, I get the 3100 volts specified in the manual.  When I  
> go to
> "operate," with nothing plugged in the back relay socket, I hear a  
> relay
> close, plate current reads about 100 mils, and the fuse blows after  
> a few
> seconds.   Since the high voltage can stay on without the fuse  
> blowing, I
> think the filter caps are ok. From the diagram, it doesn't seem  
> that the
> relay should close with the relay line open.  I'm not experienced  
> with amps,
> so any suggestions would be welcome!

You may be able to get a lot of information from the AMPS reflector.  
I would start by looking in the searchable archives: http:// 
lists.contesting.com/mailman/listinfo/Amps

The SB-1000 and the Ameritron AL-80 are very similar designs. You  
should also do searches on the web for these.

I have an AL-80A, which is a complete re-design of the AL-80. (The  
original AL-80 had a number of problems that were fixed) I'd agree  
that having the relay kick in with nothing connected to the relay  
line is not right. There's clearly something wrong with the control  
circuitry.

Fuses blowing is an interesting issue. Even if you key up the amp  
with no signal, you should see nearly 100 ma of plate current. Does  
the plate voltage stay around 3 kV when it keys?

Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901

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