The fuse can be looked at two ways. 1.it provides over current protection.
2.it won't provide polarity protection.
Some techs prefer to put the diode before the fuse as a practice to keep positive voltage off the ground plane.
Now the diode installed after the fuse will do the same but if you miswire anything after the fuse,then you will be holding a really neat looking paper weight. The diode only conducts one way and I personally have used this method to protect some of my equipment. A fuse is a fuse. Only protects from current. I prefer to protect my equipment from reverse polarity before it gets into the ground side. I do this because I have repaired many rigs with fuse first, and the owner hooked up the pwr source wrong. You can also wire it in series with ur power cord externally .some chips will fry before u get the display to glow. - 5 or - 12 is a whole lot of hurt to a static sensitive chip. Just my two cents worth.
Everyone has their own way.
73s
Have fun
David
ka9koj
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On Tue, 5/22/18, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
Subject: Re: [BITX20] #ubitx #ubitx-help
To:
[email protected] Date: Tuesday, May 22, 2018, 10:36 AM
No mention of
"fuse" here:??
What looks like a fuse at the top left of the
schematic is labeled "ON/OFF",
so
I take that to be the power switch on the volume pot.
The 26 gauge stranded wire in
the wiring harness might be considered an adequate fuse by
some.
Unfortunately that comes after the
shunt protection diode.? As you so rightly pointed out.?
;-)
Jerry
On Tue, May
22, 2018 at 03:13 am, ajparent1/KB1GMX wrote:
For the life of me I do not understand why the
diode is before the fuse.
The fuse should always be first as it needs to
operate for all faults even reverse polarity.
