Topics

A simple PVC PIPE audio filter for the Cricket


WA0ITP
 

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 speaker 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 will need a little outboard amp (tape it to the filter) to drive the speaker.  This thing could be built similar to a trombone, so I may include a sliding insert (or an outside tube) that changes the resonant freq from abt 800 cycles (8.5") 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?
72 WAØITP
I love this radio stuff.
www.wa0itp.com
www.4sqrp.com
On 5/3/2017 12:44 PM, Charles Powell 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 - almost as well as the filters on my K2.


72,

Charles
NK8O

On May 3, 2017, at 12:34 PM, Walter - K5EST walter.k5est@... [4sqrp] <4sqrp@...> wrote:


Keeping in the minimalist fashion, my old friend the Red Solo Cup Resonance CW filter does a great job at nearly no expense. The design has been around for a long time. The URL is to a U-Tube video.

https://www.youtube.com/watch?v=XN8FUr0m1Po

or if can get away with a scavenger hunt in the kitchen.....

https://www.youtube.com/watch?v=2_giOx8SNnY&t=134s

Happy CWing........de... Walter - K5EST




RWeeks <neotoxo54@...>
 

Those PVC CW Resonant speakers work very well.  I've built and tuned several (one for each rig) AND I am in the process of building another switch-box so as to allow me to route any rigs output to a combination of components...
1. straight to a resonant speaker
2. straight to a headset amp then to speaker
3. to a common CALF filter and to speaker
3. to a common CALF filter then to the headset amp and to speaker

My calf filter is primarily for audio level control (lightning crasher hurt when using headsets)

Looking forward to getting my cricket on the air soon.

SENT FROM MY IPAD MINI
Rocky Weeks, AF5AF
East Arkansas Fur Takers, FTA Chap 29B
Arkansas Trappers Assoc.
South Western Arkansas Fur Takers, FTA Chap 29A

On May 3, 2017, at 14:10, WA0ITP wa0itp@... [4sqrp] <4sqrp@...> wrote:

 

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 speaker 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 will need a little outboard amp (tape it to the filter) to drive the speaker.  This thing could be built similar to a trombone, so I may include a sliding insert (or an outside tube) that changes the resonant freq from abt 800 cycles (8.5") 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?

72 WAØITP
I love this radio stuff.
www.wa0itp.com
www.4sqrp.com
On 5/3/2017 12:44 PM, Charles Powell 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 - almost as well as the filters on my K2.


72,

Charles
NK8O

On May 3, 2017, at 12:34 PM, Walter - K5EST walter.k5est@... [4sqrp] <4sqrp@...> wrote:


Keeping in the minimalist fashion, my old friend the Red Solo Cup Resonance CW filter does a great job at nearly no expense. The design has been around for a long time. The URL is to a U-Tube video.

https://www.youtube.com/watch?v=XN8FUr0m1Po

or if can get away with a scavenger hunt in the kitchen.....

https://www.youtube.com/watch?v=2_giOx8SNnY&t=134s

Happy CWing........de... Walter - K5EST




w2sh@...
 

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

Sent: Wednesday, May 3, 2017 3:10 PM
To: 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 speaker 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 will need a little outboard amp (tape it to the filter) to drive the speaker.  This thing could be built similar to a trombone, so I may include a sliding insert (or an outside tube) that changes the resonant freq from abt 800 cycles (8.5") 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?

72 WAØITP
I love this radio stuff.
www.wa0itp.com
www.4sqrp.com
www.wa0itp.com
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@... [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 - almost as well as the filters on my K2.


72,

Charles
NK8O

On May 3, 2017, at 12:34 PM, Walter - K5EST walter.k5est@... [4sqrp] <4sqrp@...> wrote:


Keeping in the minimalist fashion, my old friend the Red Solo Cup Resonance CW filter does a great job at nearly no expense. The design has been around for a long time. The URL is to a U-Tube video.

https://www.youtube.com/watch?v=XN8FUr0m1Po

or if can get away with a scavenger hunt in the kitchen.....

https://www.youtube.com/watch?v=2_giOx8SNnY&t=134s

Happy CWing........de... Walter - K5EST




Ronald Morrison
 

A search for "CW resonant speaker" turns up several links, one of which is:





Sam Neal
 

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. That
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@msn.com [4sqrp]" <4sqrp@yahoogroups.com>
To: "4sqrp@yahoogroups.com" <4sqrp@yahoogroups.com>, "wa0itp@mchsi.com"
<wa0itp@mchsi.com>
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@yahoogroups.com <4sqrp@yahoogroups.com> on behalf of WA0ITP
wa0itp@mchsi.com [4sqrp] <4sqrp@yahoogroups.com>

Sent: Wednesday, May 3, 2017 3:10 PM
To: 4sqrp@yahoogroups.com; 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 speaker
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 will
need a little outboard amp (tape it to the filter) to drive the speaker. This
thing could be built similar to a trombone, so I may include a sliding insert
(or an outside tube) that changes the resonant freq from abt 800 cycles (8.5")
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?

72 WAØITP
I love this radio stuff.
www.wa0itp.com<http://www.wa0itp.com>
www.4sqrp.com<http://www.4sqrp.com>

[http://www.wa0itp.com/w8dizcntr2.jpg]<http://www.wa0itp.com/>

WAŘITP Home - Promoting QRP operating and
Construction.<http://www.wa0itp.com/>
www.wa0itp.com
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@yahoo.com<mailto:doctorcwp@yahoo.com> [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 - almost
as well as the filters on my K2.

72,

Charles
NK8O

On May 3, 2017, at 12:34 PM, Walter - K5EST
walter.k5est@gmail.com<mailto:walter.k5est@gmail.com> [4sqrp]
<4sqrp@yahoogroups.com<mailto:4sqrp@yahoogroups.com>> wrote:


Keeping in the minimalist fashion, my old friend the Red Solo Cup Resonance CW
filter does a great job at nearly no expense. The design has been around for a
long time. The URL is to a U-Tube video.

https://www.youtube.com/watch?v=XN8FUr0m1Po

or if can get away with a scavenger hunt in the kitchen.....

https://www.youtube.com/watch?v=2_giOx8SNnY&t=134s

Happy CWing........de... Walter - K5EST


Charles W. Powell
 

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).

72,

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. That
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@... [4sqrp]" <4sqrp@...>
To: "4sqrp@..." <4sqrp@...>, "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@...> on behalf of WA0ITP
wa0itp@... [4sqrp] <4sqrp@...>

Sent: Wednesday, May 3, 2017 3:10 PM
To: 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 speaker
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 will
need a little outboard amp (tape it to the filter) to drive the speaker. This
thing could be built similar to a trombone, so I may include a sliding insert
(or an outside tube) that changes the resonant freq from abt 800 cycles (8.5")
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?

72 WAØITP
I love this radio stuff.
www.wa0itp.com<http://www.wa0itp.com>
www.4sqrp.com<http://www.4sqrp.com>

[http://www.wa0itp.com/w8dizcntr2.jpg]<http://www.wa0itp.com/>

WAŘITP Home - Promoting QRP operating and
Construction.<http://www.wa0itp.com/>
www.wa0itp.com
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@...<mailto: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 - almost
as well as the filters on my K2.

72,

Charles
NK8O

On May 3, 2017, at 12:34 PM, Walter - K5EST
walter.k5est@...<mailto:walter.k5est@...> [4sqrp]
<4sqrp@...<mailto:4sqrp@...>> wrote:

Keeping in the minimalist fashion, my old friend the Red Solo Cup Resonance CW
filter does a great job at nearly no expense. The design has been around for a
long time. The URL is to a U-Tube video.

https://www.youtube.com/watch?v=XN8FUr0m1Po

or if can get away with a scavenger hunt in the kitchen.....

https://www.youtube.com/watch?v=2_giOx8SNnY&t=134s

Happy CWing........de... Walter - K5EST



Sam Neal
 

Hello,

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@yahoo.com>
To: 4sqrp@yahoogroups.com, Sam Neal <n5af@usa.net>
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).

72,

Charles - NK8O


On May 3, 2017, at 9:22 PM, 'Sam Neal' n5af@usa.net [4sqrp]
<4sqrp@yahoogroups.com> 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.
That
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@msn.com <mailto:w2sh@msn.com> [4sqrp]"
<4sqrp@yahoogroups.com <mailto:4sqrp@yahoogroups.com>>
To: "4sqrp@yahoogroups.com <mailto:4sqrp@yahoogroups.com>"
<4sqrp@yahoogroups.com <mailto:4sqrp@yahoogroups.com>>, "wa0itp@mchsi.com
<mailto:wa0itp@mchsi.com>"
<wa0itp@mchsi.com <mailto:wa0itp@mchsi.com>>
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@yahoogroups.com <mailto:4sqrp@yahoogroups.com>
<4sqrp@yahoogroups.com <mailto:4sqrp@yahoogroups.com>> on behalf of WA0ITP
wa0itp@mchsi.com <mailto:wa0itp@mchsi.com> [4sqrp] <4sqrp@yahoogroups.com
<mailto:4sqrp@yahoogroups.com>>

Sent: Wednesday, May 3, 2017 3:10 PM
To: 4sqrp@yahoogroups.com <mailto:4sqrp@yahoogroups.com>; 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
speaker
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
will
need a little outboard amp (tape it to the filter) to drive the speaker.
This
thing could be built similar to a trombone, so I may include a sliding
insert
(or an outside tube) that changes the resonant freq from abt 800 cycles
(8.5")
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?

72 WAØITP
I love this radio stuff.
www.wa0itp.com <http://www.wa0itp.com/><http://www.wa0itp.com
<http://www.wa0itp.com/>>
www.4sqrp.com <http://www.4sqrp.com/><http://www.4sqrp.com
<http://www.4sqrp.com/>>

[http://www.wa0itp.com/w8dizcntr2.jpg
<http://www.wa0itp.com/w8dizcntr2.jpg>]<http://www.wa0itp.com/
<http://www.wa0itp.com/>>

WAŘITP Home - Promoting QRP operating and
Construction.<http://www.wa0itp.com/ <http://www.wa0itp.com/>>
www.wa0itp.com <http://www.wa0itp.com/>
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@yahoo.com <mailto:doctorcwp@yahoo.com><mailto:doctorcwp@yahoo.com
<mailto:doctorcwp@yahoo.com>> [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 -
almost
as well as the filters on my K2.

72,

Charles
NK8O

On May 3, 2017, at 12:34 PM, Walter - K5EST
walter.k5est@gmail.com
<mailto:walter.k5est@gmail.com><mailto:walter.k5est@gmail.com
<mailto:walter.k5est@gmail.com>> [4sqrp]
<4sqrp@yahoogroups.com
<mailto:4sqrp@yahoogroups.com><mailto:4sqrp@yahoogroups.com
<mailto:4sqrp@yahoogroups.com>>> wrote:

Keeping in the minimalist fashion, my old friend the Red Solo Cup Resonance
CW
filter does a great job at nearly no expense. The design has been around for
a
long time. The URL is to a U-Tube video.

https://www.youtube.com/watch?v=XN8FUr0m1Po
<https://www.youtube.com/watch?v=XN8FUr0m1Po>

or if can get away with a scavenger hunt in the kitchen.....

https://www.youtube.com/watch?v=2_giOx8SNnY&t=134s
<https://www.youtube.com/watch?v=2_giOx8SNnY&t=134s>

Happy CWing........de... Walter - K5EST



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.
72
Johnny AC0BQ 


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

Hello,

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).

72,

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.
That
> 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@... 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@...
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
speaker
> 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
will
> need a little outboard amp (tape it to the filter) to drive the speaker.
This
> thing could be built similar to a trombone, so I may include a sliding
insert
> (or an outside tube) that changes the resonant freq from abt 800 cycles
(8.5")
> 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?
>
> 72 WAØITP
> I love this radio stuff.


<http://www.wa0itp.com/>>
>
> 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 -
almost
> 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@...>walter.k5est@...
walter.k5est@...>> [4sqrp]
> <4sqrp@...
4sqrp@...>4sqrp@...


4sqrp@...>>> wrote:
>
> Keeping in the minimalist fashion, my old friend the Red Solo Cup Resonance
CW
> filter does a great job at nearly no expense. The design has been around for
a
> long time. The URL is to a U-Tube video.
>
> https://www.youtube.com/watch?v=XN8FUr0m1Po
<https://www.youtube.com/watch?v=XN8FUr0m1Po>
>
> or if can get away with a scavenger hunt in the kitchen.....
>
> https://www.youtube.com/watch?v=2_giOx8SNnY&t=134s
<https://www.youtube.com/watch?v=2_giOx8SNnY&t=134s>
>
> Happy CWing........de... Walter - K5EST
>
>
>

--
Check out the 4SQRP website at 4sqrp.com


Leland L. Bahr
 

For those interested in building a tuned PVC pipe speaker, you might want to look at a 4 ohm 3 watt speaker sold by Marlin P. Jones & Associates. This speaker is 2 inches square. Even though it is 2 inches square, it can handle 3 watts as it has a very nice heavy magnet for it's size. They are listed at $1.29 each. ( http://www.mpja.com ) They have an aluminum diaphragm with a rubber surround. Made better then normal for a small speaker this size.
Lee, w0vt