[Elecraft] Stereo Speaker for K3

[Don Wilhelm]

Steve,

With audio, you can forget about matching impedance, it is the voltage 
that matters.  An audio amplifier will operate into a 4 ohm or a 1000 
ohm load just fine.   With the 4 ohm load, power is required, but for a 
1000 ohm load, not much power is necessary.

But more direct to your question, the K3 or K3S does *not* need 
amplified speakers, but for the KX3 you will likely want amplified 
speakers for adequate volume in the home hamshack application - the 
audio amplifier in the KX3 is designed for low receive current draw and 
that means it does not have powerful audio, but is entirely sufficient 
for headphones or the efficient internal speaker.
There is no harm in using amplified speakers on the K3 (K3S) but it has 
enough audio power to use non-amplified speakers.
Yes, ordinary computer speakers are subject to RF pickup resulting in 
'howls' and other noises during transmission, thus my recommendation to 
use shielded speakers (if they are amplified) in the hamshack.

The COMspkr is a communications quality speaker, and is great for normal 
ham use.  If you want full range audio for HiFi SWLing, use something else.

73,
Don W3FPR

On 11/22/2015 4:15 PM, Steve Ellington wrote:
> Am I missing something? Why would one want to use an amplified speaker on a
> K3 since the radio already has an amplifier? Doing so would seem to invite
> distortion and RF pickup. The K3's audio output is supposed to have a 4 ohm
> load and computer speakers are probably closer to 1000 ohms. It's almost
> like having no load at all. I don't think that's good for the K3's output
> chip.
>
> I have the West Mtn. speakers here and they sound rather poor compared to
> almost any comparable computer speaker.
>
>