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Re: [RFI] What was that noise?

To: rfi <rfi@contesting.com>
Subject: Re: [RFI] What was that noise?
From: Rob Atkinson <ranchorobbo@gmail.com>
Date: Fri, 25 Jun 2021 04:54:38 -0500
List-post: <mailto:rfi@contesting.com>
> The Black and Decker unit has a wart, but its output is an odd 8.5 VDC.

For those new to the wall wart waltz, or the switching supply shuffle,
there are two things to check:  1.  Make sure the linear replacement
polarity is correct on the DC plug to the load.  2.  Check the DC
voltage level coming out of the replacement.  Linear supply wall warts
are all over the place from what's stamped on their cases.  I've seen
supposedly 9 v. wall warts measure 16 v., but that's unloaded.  Often
the devices they were sold with were not very voltage critical, but
the item you want to use, like an antenna preamp, may need supply
voltage close to what is specified.   And of course, make sure the
replacement can supply the current demand.  If your load doesn't need
much current compared to what the w.w. was intended for, its voltage
may stay too high.  Basically, don't just haul out a replacement
linear supply and plug it in and try it.

Rob
K5UJ
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