[Elecraft] rcv current draw K2 vs K3

[Wayne Burdick]

On Mar 13, 2015, at 11:57 AM, bs usb <bsusb at k5dkz.com> wrote:

> I was looking at test data, comparing K3 to K2 and found that while the K2 is rated at 150ma, the K3 draws 600ma.  Is this correct?

Not quite. The K2's receive-mode current drain can be .150-.250 A depending on what's enabled, what options are installed, and speaker volume.

The K3 is around .9-1.2 A, for the same reasons. 

To put these values into perspective: most modern desktop transceivers (many with performance ratings far below that of the K3) draw more like 2 to 4 amps in receive mode.


> …what is in the K3 that requires 4x more current?  What do the additional current consumers contribute to the operation of the radio?

The K3 has the following stages that add both current and features or performance advantages:

- high-dynamic-range, dual-conversion superhet architecture with heavily biased mixers, post-amp, etc.
- multiple stages of high-bias PIN-diode T/R switching and other PIN-diode path switching
- high-performance 32-bit DSP I.F.s for main and sub receiver
- large, brightly lit LCD with dual VFO displays, alphanumeric display for text decode, etc.
- four multi-function encoders, each with two LED indicators
- ATU that uses non-latching relays to maximize tuning speed
- digital voice recorder (DVR)
- high-power stereo AF amplifier
- misc. support and I/O circuitry (not found on the K2)

This isn't a comprehensive list, but you get the idea. Yes, it's more current drain than a K2, but we were able to provide excellent performance and a wide range of features in the K3 while consuming 1/2 to 1/4th the current drain of most transceivers in its class.

The KX3 is another interesting point of comparison. Its receive current drain is about 200-250 mA, typically, while providing the highest performance of any ultra-compact transceiver by a wide margin.

73,
Wayne
N6KR