A very similar amplifier (same amp IC, similar layout) here:
<https://www.amazon.com/HiLetgo-TDA7297-Version-Amplifier-Dual-Channel/dp/B00LOG51EE/135-0623238-9759344>
73,
... Joe, W4TV
On 2026-02-17 1:44 AM, Walter Underwood via Elecraft wrote:
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
<[email protected]> 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 <[email protected]>
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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