[Elecraft] To Fuse or Not To Fuse...

[Ron D'Eau Claire]

Let me add a little personal experience of my own with the KPA100 to =
this
thread about not just how important it is to have a fuse, but using the
right parts.=20

There was ONE missing part when I built my KPA100. It was half of the =
holder
for the in-line fuse that is provided with the amplifier. No problem, I
thought, and picked one up at the local hardware store.=20

After several days of operating, perhaps a week, DC power to the K2/100
became intermittent, as if the power connector wasn't assembled or =
inserted
properly. But it was.=20

Finally I pulled the entire cable out from behind the operating desk to
reach the fuse holder near the power supply end. The fuse holder was =
WARM to
the touch. Opening it I discovered that the replacement fuse holder,
although "rated" at 16 amps (that was the size fuse furnished with it) =
was
heating up and MELTING. Since there is a spring inside pushing against =
the
fuse, as the plastic holder heated it was stretching until the spring =
was no
longer long enough to hold the fuse in good contact with the terminals =
and
the connection became intermittent. Of course, the poorer the contact, =
the
more heat was generated and the more the holder stretched.=20

This time I dropped by the local automotive supply shop and bought a
somewhat more expensive holder. I've had no further troubles from
over-heating fuses and melting holders.=20

My K2/100 draws normal currents, BTW. Something from 11 to 15 amps =
depending
upon the band.=20

Ron AC7AC