[Elecraft] K3: Power cable question

[Ron D'Eau Claire]

Hi Julius:

I measure just over 20 Amps under some bands and conditions running the K3
at 100 watts. Like the K2, I suspect the current draw varies a bit depending
upon the rig, the actual parameters of some of the transistors, etc. That's
normal, according to the K3 specs, which rate the current demand at 17-22
amps at 100 watts in transmit

IMX fuses have a nasty habit of suddenly opening after being cycled a number
of times near their rated limit, even the 'slo-blo' type that are supposed
to offer a little resistance against sudden failure when their current limit
is reached will sometimes open unexpectedly.

I've seen fuses operating near their current limits develop cracks so they
act like thermal switches, causing power to go off suddenly then, after a
few seconds (while the fuse cools) suddenly come back on, then switch off
again as soon as a higher current is drawn such as for transmitting.
Eventually they fail completely, but in the meantime the symptoms can be
pretty confusing.  

As a matter of practice I try to allow significant headroom between the
rating of any fuses and the actual current draw, and I always have spare
fuses on hand since they can and do fail over time, even if not subjected to
excessive current. 

Ron AC7AC



-----Original Message-----

Ron,

I've been using my K2 cable with my K3, including
contests, without an issue. 

Considering what the KPA100 will do with my 160M
setup, in the way of drawing current, I think there is
enough wiggle room not to worry too much.

The K3 barely gets warm when I run :o)

73,
Julius