I'm in general agreement with Bob, but there are some details.
(1) You don't want to melt you power supply wires. If you trust
the power supply device to properly current limit, then you
don't need a fuse. If you are using something like my old
solar/deep cycle battery supply, you definitely need a fuse.
(2) The important thing about voltage drop is getting enough
voltage to the final amp in the radio to avoid producing all
kinds of distortion in the output signal. This distortion
results in a bad signal that causes interference with neighbors
on the band. If you are running 14.5 volts receive load, you can
afford a bigger voltage drop than if you are running off of
batteries at 12 volts receive load.
In this latter case, you probably can't afford any voltage drop
at all and should throttle back to a maximum of 50 watts or so
to clean up your signal.
Our real-life experience was one Field Day with our QRP digital
K3 station. The deep cycle lead/acid battery was getting tired.
The people in the CW tent were complaining of interference from
the digital station. A fresh battery fixed the problem.
73 Bill AE6JV
On 7/22/21 at 6:27 AM, [email protected] (Bob McGraw) wrote:
With that power supply, which has both good over voltage
protection and current limiting, adding fuses in the DC line
will add resistance to the line. Even being a small amount,
it will affect voltage regulation from no load to rated load at
the radio. For this reason I do not recommend adding
fuses to the DC power cables.
I agree that all 100 watt transceivers should have their DC
power leads connected direct to the power supply terminals and
not through any DC distribution device. As a rule,
receive load to 100 watt CW/key closed transmit load, the
voltage drop at the radio should be less than 0.5 volts.
----------------------------------------------------
Bill Frantz | Art is how we decorate space,
408-348-7900 | music is how we decorate time.
www.pwpconsult.com | -Jean-Michel Basquiat
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