Re: A simple PVC PIPE audio filter for the Cricket

Johnny AC0BQ

Here is a link to the author's article that did the write up  on the resonant speaker for QST.
I found it on Google.
Very simple and easy to build.
Johnny AC0BQ 

On Fri, May 5, 2017 at 4:08 PM 'Sam Neal' n5af@... [4sqrp] <4sqrp@...> wrote:


Where can I find a " hopefully virgin " cuspidor/spittoon at? It adds class to
the appearance of the housing of this speaker.

Sam Neal N5AF
Celebrating 60 Years In Amateur Radio

------ Original Message ------
Received: Fri, 05 May 2017 03:40:11 PM CDT
From: Charles Powell <doctorcwp@...>

To: 4sqrp@..., Sam Neal <n5af@...>
Subject: Re: [4sqrp] A simple PVC PIPE audio filter for the Cricket

I made a pair of these Dixie Cup resonant speakers today. Remarkably, they
have a very sharp peak at 600 Hz (my preferred center frequency). I opened up
the filter on the KX3 and found that the speakers were better than tightening
down the filter on the radio. It is the equivalent of about a 100 Hz filter,
but much better sonic quality. I am impressed! Now I have extra Dixie cups
for summer as well. (I made two because the KX3 needs “stereo” to work
“Dual Watch” mode.

One suggestion that was not shown in the YouTube video: After attaching the
speaker to the cup, place another cup underneath it, up against the bottom of
the speaker, and hot glue it in place. I found this narrows the bandwidth
considerably, and fortunately at just the right frequency (for me, anyway).


Charles - NK8O

> On May 3, 2017, at 9:22 PM, 'Sam Neal' n5af@... [4sqrp]
<4sqrp@...> wrote:
> Hello,
> I made it's el-cheapo little brother ( some old issue of Popular Electronics
> out of a Pringles potato chip can and the speaker out of an old CB radio.
> sounded very good, so I can imagine that it's big brother from QST will be
> much better.
> 73,
> Sam Neal N5AF
> Celebrating 60 Years In Amateur Radio
> _______________________________________________________
> ------ Original Message ------
> Received: Wed, 03 May 2017 05:36:31 PM CDT

> From: "Charles Moizeau w2sh@... w2sh@...> [4sqrp]"
<4sqrp@... 4sqrp@...>>
> To: "4sqrp@... 4sqrp@...>"
<4sqrp@... 4sqrp@...>>, "wa0itp@...
> <wa0itp@... wa0itp@...>>
> Subject: Re: [4sqrp] A simple PVC PIPE audio filter for the Cricket
> By all means have a look at the February 2017 issue of QST, pages 43-45, "A
> Resonant Speaker for CW", for good ideas and a nicely crafted result.
> 72,
> Charles, W2SH

> From: 4sqrp@... 4sqrp@...>
<4sqrp@... 4sqrp@...>> on behalf of WA0ITP
> wa0itp@... wa0itp@...> [4sqrp] <4sqrp@...

> Sent: Wednesday, May 3, 2017 3:10 PM

> To: 4sqrp@... 4sqrp@...>; Charles Powell;

Walter - K5EST
> Subject: Re: [4sqrp] A simple PVC PIPE audio filter for the Cricket
> Lets build one!
> A hunk of pvc pipe works very well, and is plenty stiff enough. I built one
> some years back, and if I could find it, I'd use it. The volume of the pipe
> doesn't matter, only the length, so I'll let the size of the junk box
> dictate the diameter of the pipe. Easy calculation too, length of
> pipe=1100/2f. Think I'll build one specifically for the Cricket, but it
> need a little outboard amp (tape it to the filter) to drive the speaker.
> thing could be built similar to a trombone, so I may include a sliding
> (or an outside tube) that changes the resonant freq from abt 800 cycles
> down to 400cycles (16.5"). It will work for any rig that will drive a
> speaker.
> I'm off to the junque box to find a speaker, anyone else want to build one
> too? Anyone have some good construction hints?
> I love this radio stuff.

> WAŘITP Home - Promoting QRP operating and

> Welcome To WAØITP's Ham Radio Web Site Promoting QRP operating and
> Construction. Pacific Mountain Central Eastern GMT
> On 5/3/2017 12:44 PM, Charles Powell

> doctorcwp@... doctorcwp@...>doctorcwp@...

doctorcwp@...>> [4sqrp] wrote:
> I had forgotten about this. I made one years ago when I first started in
> radio, and used it with my FT-101EE. As i recall, it worked quite well and
> the video bears this out. I have a boatload of small speakers around here
> somewhere. I made a tuned speaker from PVC that also works very well -
> as well as the filters on my K2.
> 72,
> Charles
> NK8O
> On May 3, 2017, at 12:34 PM, Walter - K5EST
> walter.k5est@...

walter.k5est@...>> [4sqrp]
> <4sqrp@...

4sqrp@...>>> wrote:
> Keeping in the minimalist fashion, my old friend the Red Solo Cup Resonance
> filter does a great job at nearly no expense. The design has been around for
> long time. The URL is to a U-Tube video.
> or if can get away with a scavenger hunt in the kitchen.....
> Happy Walter - K5EST

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