[AMRadio] B&W 5100B Modulation Update

Mike Dorworth K4XM k4xm at arczip.com
Wed Oct 13 13:06:47 EDT 2004

Take a meter such as a Simpson 260, put lead in output jack, range switch on
AC 2.5 or 10 volt scale. Read B plus, there should be no ac on the meter. If
you meter has no output position use a .1 mFd cap in series with one of the
leads and read AC volts on the DC bus.You are looking for ripple, most
scopes don't like to look at this much B+ so simple output meter check good
enough. You could parallel a good cap to be sure.. Hope this helps.

 The capacitors are most likley completely gone.. Mike K4XM

Now that I have had some time to troubleshoot the B&W 5100B modulation here
is what I found. The B+ is around 600 volts with no modulation and I as
start to modulate and watch the scope when it reaches about 50% modulation
the B+ drops from 600 to around 400 volts

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