[Elecraft] K3: How many amps does it draw?

[Tom Hammond]

Doug Zwiebel, KR2Q, posed the following...

>Wondering if anybody has measured this...
>
>I have the K3 with the KPA3, but I run it almost all the time at 5
>watts output (5.0 setting).
>
>What is the max amps that this configuration might draw, assuming a
>good SWR and a normal voltage (indoor) supply?  I want to see "how
>small" (but safe) a power supply I can use.

Obviously, this is NOT the absolute answer to your query, but it's
what I just measured on my (Field Test) K3, on 20M CW, into a known
accurate 50 Ohm load with the ATU in BYPASS mode, using an in-line
Fluke 187 DMM in the 10A position and the shortest 'test' clip-leads
(about 4" each) I had available.

   K3 #0008

   Mode      Current (A)

    OFF      0.055 A (55 mA)

    RX       0.99 A  (990 mA)

     1W TX   2.56 A

     5W TX   3.37 A

    10W TX   3.95 A

    12W TX   4.14 A  (power setting just BEFORE KPA3 enabled)

    13W TX   8.90 A  (KPA3 just enabled)

Given a small amount of resistive losses in the (alligator clip)
connections to the DC leads, the DC voltage applied to the K3
(measured BY the K3) varied from 13.9VDC (RX), 13.7 VDC (1W TX),
to 13.3VDC (13W TX).

This may (or may NOT) be representative of all K3s... YMMV..

73,

Tom Hammond   N0SS