[Elecraft] That Endless Speaker Thread...

[Ron D'Eau Claire]

Listening around tonight I happened to be the only one in the house so I
used the speaker on my K2. I almost always wear phones.

I use a 500 Hz sidetone frequency. It was very obvious to me that the
audio peak as I tuned through signals was occurring at well below 500
Hz. So I got out my sound level meter. It's well calibrated and handy
(used it for setting up audio systems). Sure 'nuf, listening to a strong
carrier (e.g. WWV) the sound level coming from the speaker was a good
8dB stronger at 300 Hz that it was at 500 Hz. That's a BIG peak and it's
way off of my filter peak at 500 Hz. 

It's not there in the phones, so it must be the speaker. 

Nope. It's the position of the K2! 

My K2 sits on the back of the operating desk and there's a bookcase next
to the end of the desk where the K2 sits. So it's in a corner. And that
corner seems to be resonant at about 300 Hz. Moving the K2 a foot away
removed all signs of the 300 Hz peak. Also, putting a deflector on top
of the K2 modified the peak. Indeed, a copy of Bill Orr's "Vertical
Antennas" propped up at about 30 degrees shifted the peak to almost
exactly 500 Hz to match my filter center frequency. (Sorry, the
venerable Bill Orr's book is out of print so you can't duplicate my
experiment, but I bet that "200 Meters and Down" by DeSoto would work
much the same). 

The point of all this is that the environment makes a WORLD of
difference in the audio response of the K2's speaker. That's largely
because it is not facing toward the operator. 

So if you're unhappy with the frequency response of the K2 speaker,
playing around with a deflector might be the most cost-effective
solution of all. 

Ron AC7AC
K2 # 1289