[Elecraft] speaker impedance

[Don Wilhelm]

Folks,
Like Bob, I have used the speaker in a tumbler too - and it works great
especially for CW.  Use one of the tapered plastic tumblers (get several and
experiment).  You can change the resonant frequency by altering the length
of the tube (saw a bit off a few of the tumblers) and by using your choice
of a closed tube (normal tumbler) or an open tube (saw the bottom of one
off).  When you find what you like, use it.  I have used an open tube
sitting on top of the cone (not touching the cone though) of a replacement
speaker for the K2 with good results.

BTW, if you have noticed, the K2 speaker sounds better with the top cover
on - the K2 'cavity' makes a good resonance chamber for that speaker, and it
sounds louder too, the enclosure makes a BIG difference.

73,
Don W3FPR

----- Original Message ----- 

> Hi John
> I've used an external speaker with my K2, s/n 12, ever since I built it.
> I use an acoustic speaker/filter, made from a thick plastic drinking glass
> with a round speaker set into it.  I don't recall the speaker impedance,
> but I didn't worry about it.  I just made it work and let it go at that.
> Mine resonates right around 560 Hz, just perfect for cw, which is all I
run
> anyway.
> Give it a try.