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On Tue, Mar 20, 2018 at 01:00 pm, Tim Gorman wrote:

Walter,

I have a 1 amp fast-blow fuse on the red lead going to the main circuit
board and a 2 amp fast-blow fuse on the brown lead going to the power
amp circuit.

My ammeter shows 2 amp peaks on the very loudest audio into the mic.
This load apparently doesn't last long enough to blow the 2amp fuse.
Usual peaks are around 1 amp

I've never seen the current go above about 250ma on receive even with
the volume control way up on a strong signal. My TDA2822W chip never
gets warm under normal use. I have used an 8ohm speaker and a 16ohm
speaker to test the current draw. I use a mono jack on the speaker lead
and a permanently wired internal speaker that the mono jack disconnects
when an external speaker is plugged in.

I suspect I can get by with a 500ma fast-blow fuse on the main board. I
might try that the next chance I get.

tim ab0wr

On Tue, 20 Mar 2018 07:16:13 -0700
"Walter" <W9KJO@...> wrote:

On Thu, Mar 15, 2018 at 06:12 pm, Tim Gorman wrote:

Jerry,

I'm not sure everyone understands what foldback current limiting
is. Your message 40729 explains it well. In action it is like a
fuse. The power supply opens the power lead until the operator
takes an action.

It is not the same thing as current limiting.

I don't have any power supplies with foldback current limiting so
for me a fuse is the next best thing.

tim ab0wr

On Thu, 15 Mar 2018 16:46:37 -0700
"Jerry Gaffke via Groups.Io" <jgaffke=[email protected]> wrote:

True.? The standard current limiting supply I described is not
something to lean on to avoid driving the final too hard, that's
not what I was suggesting. If there's a current limit on the
finals, should be foldback current limiting:
/g/BITX20/message/40719

OK Great info so what size fuse?? What is the maximum safe current
for the circuit?

Thanks
?
--
73, W9KJO
Walter

I wonder if 2 amps would remain true for digital modes as well?
?
--
73, W9KJO
Walter