[Gang - This post was made circa April-May 2000 on QRP-L mail list by Ed WE6W;  it is 
used with Ed's permission......73, monty N5FC]

---- WE6W Resonant Speaker----

4 Inch diameter sphere with 2 inch diameter hole in It
1 inch diameter speaker.
6.5 inch length of 2 inch I.D. PVC pipe.
2.65 inch length of 1.1 inch I.D. PVC Pipe.
wood disk 0.25 thick, 2 inch Diameter with hole in center for 1.1 I.D. PVC pipe.

Note PVC diameters, inside and out, are VERY Variable. 
Measure and trim your work accordingly.

OPTIONAL Tuning Plunger for rear sphere
0.75 inch hole in sphere, 90 degrees from 2 inch hole. 6 inch .75 S.D. metal tube.
Plunger  is 6 inch metal or wood rod with wood and foam or teflon piston 
screwed/epoxied to end.  Expand teflon by tightening two nuts, one on each side
 of Teflon and threaded end, by tightening. if using wood discs, add 1 inch cylinder
 of foam around shaft to support the plunger and provide necessary friction.

Attach wires to speaker and run wires into sphere and out of small hole at rear of 
sphere (directly opposite speaker)

Mount speaker about .1 inch inside sphere opening.  The face of the speaker is 
0.1 inch back of the plane of the opening. The speaker is firing outt of the sphere.
Heat a needle and push 4 holes Into speaker plastic rim and attach small buss wire. 
 Punch holes into lip of sphere opening and tie off wires firmly.  Glass or metal spheres 
require some ingenuity for mounting the speaker.

Speaker is now suspended and centered in sphere opening, with the outward firing 
speaker about 0.1 inch from the plane of the opening and inside the sphere.  There 
is a volume of air around the speaker edges.  Do not close this area off.

Epoxy or tape sphere to 8.5 inch PVC pipe so speaker fires Into pipe.  Performance 
requires all joints be aIr tight.  (Tuning plunger included).

Press-fit or epoxy 0.75 O.D. metal tube to other hole in sphere. Add plunger assembly 
now or later.

Using metal ruler and permanent marker, measure from the remaining opening in 8.5 
inch tube and make a mark at 4.25 Inches (The center) of the inside of the tube.  
Slide the 2.65 inch tube into the wood disc and center the tube with about 1.2 inches 
of tube on either side of the disc.
Epoxy tube in place or tape the tube so it won't slide in/out of the disc.
Slide disc/small tube assembly into the big tube and just past  he  4.25 inch mark 
so you can see the mark made previously.. The disc should fit snugly but should
 be movable for tuning.

Connect speaker to radio or audio source.

Adjust  audio source level and frequency to your desired tone.

Peak  the resonant speaker by sliding disc/small tube assembly
in/out of the larger tube by no more than 3 inches either side of center.     I used 
a metal hook tool. The hook passes thru the small  tube and you can  pull the disc 
assembly out, or you push the assembly in  using two tools or  gradually rocking the 
disc with one tool.

After peaking the desired tone, now you adjust for best cut-off and bandpass using 
the rear plunger if you installed it.

Set plunger all the way out and just covering the end of the metal pipe.  Set signal 
source about 100 Hz ABOVE desire tone set previously.  Adjust rear plunger to null 
this tone.

Recheck desired tone and peak with disc as before.
You will have lots of fun experimenting with different frequencies and bandpass 
characteristics.  It is especially exciting to tune the plunger and hear the radio QRN 

Note, this speaker has approximately +/- 45 HZ bandwidth. is approximately 4 dB 
over typical radio speaker and the signal/noise improvement is approximately 
12 to 20 dB depending on construction materials and quality of construction of the 

That is it.  Enjoy your WE6W resonant speaker.

(c) 1999 Ed Loranger mailtowe6w@qsl.net Permission to copy and distribute 
granted for non-profit use only.

-Ed  AR QRP Millennium QSO's=560/2000
72, Ed WE6W, A-i OP; http//www.qsl.net/we6w  Santa Rosa, CA QRP-Z#106 
QRP-L#lc6s AR#112 NC42227 ARCI#.9397 ARS#275

>from we6w@qsl.net Wed Apr 14 200516 1999
Subject Re: Resonant Speaker project

Hi gang, I corrected some spelling errors (2), and I have some clarity regarding the 

Maximum 4 inch I.D. HOLLOW sphere.  Plastic, metal glass etc.

Sources include XMAS ornaments, light diffusers from a vanity, I even used a 60 
watt light bulb, standard G.E., that was set in epoxy and another in concrete.

I made a quick stand for the device by using a 4x4 Inch by 2 Inch piece of rigid 
packing foam.  I cut a 2 inch or so diameter hole in the foam and slipped it over 
the big tube.  Also, I build a wood stand that was nice.

A close friend made a real fancy stand out of cherry wood.

ONE CAUTION  A sudden strong signal can bottom out  the little 1 inch speaker.  
Good luck finding a I watt speaker of that size..

So watch the speaker drive when operating thIs device.

Wishing you all the best of %n using it.
72/	Ed Loranger we6w/6

-Ed  AR QRP Millennium QSO's--560/2000
72, Ed WE6W, A-l OP; http//www.qsl.net/we6w  Santa Rosa, CA QPP-z#106 
QRP-L~ 068 AR#,112 NS#2227 ARCI#9397 ARS#275