[Elecraft] KX3 with external speaker

[Walter Underwood]

A while ago, I added a 12 V audio amp to my setup and wrote it up on my blog. I don’t think that particular amp is available now, but I’m sure there are similar ones.

https://observer.wunderwood.org/2017/03/04/speakers-for-my-elecraft-kx3/

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On Feb 16, 2026, at 4:30 PM, Walter Underwood via Elecraft <elecraft at mailman.qth.net> wrote:
> 
> The KX3 “PHONES” jack is for headphones. It produces 100 mW. —wunder, K6WRU
> 
>> On Feb 16, 2026, at 3:44 PM, Jim Brown via Elecraft <elecraft at mailman.qth.net> wrote:
>> 
>> On 2/16/2026 3:15 PM, Phil Hystad via Elecraft wrote:
>>> Can someone give pointers on this?
>> 
>> The K3, K3S, and K4 have separate audio power amplifiers for headphones and speakers, each with their own individual output jacks. I haven't studied the schematic, but I suspect that the KX3 has only the amplifiers for headphones. Speakers require considerably more power.
>> 
>> The headphone output could probably drive a powered speaker (that is, one with its own built-in amplifier), but powered speakers are notoriously bad for RFI, both generating noise and being susceptible to nearby transmitters, so are unlikely to be a solution.
>> 
>> 73, Jim K9YC
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