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Gang,
I accepted the Soldersmoke DC Receiver Challenge on April 19th.
Here is my 3 stage audio amplifier I finished this morning.
Please join in on the fun!
73,
Alan, N8WQ
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Hi Alan,
I have looked at it, but I do not know where to begin.?
?
Besides, it needs a PTO.? I do not have a 3D printer to make the part.
?
I think one ham used a fix frequency oscillator in place of the PTO.? I wonder what the frequency was.?? W1AW???
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Or I use a different analog VFO that could be used instead of a PTO.
?
73 Daniel KK4MRN
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I can think of lots of ways to build that without a 3d printer. They all involve hot glue ;)? On Mon, Apr 21, 2025 at 8:37?AM Daniel KK4MRN via <daniel-kk4mrn.skipper529= [email protected]> wrote:
Hi Alan,
I have looked at it, but I do not know where to begin.?
?
Besides, it needs a PTO.? I do not have a 3D printer to make the part.
?
I think one ham used a fix frequency oscillator in place of the PTO.? I wonder what the frequency was.?? W1AW???
?
Or I use a different analog VFO that could be used instead of a PTO.
?
73 Daniel KK4MRN
?
?
?
?
?
?
?
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Not ashamed to have built many projects with hot glue and velcro
strips.
KB9BVN
On 4/21/2025 11:51 AM, Ryan Flowers via
groups.io wrote:
toggle quoted message
Show quoted text
I can think of lots of ways to build that without a 3d
printer. They all involve hot glue ;)?
On Mon, Apr 21, 2025 at
8:37?AM Daniel KK4MRN via
<daniel-kk4mrn.skipper529= [email protected]>
wrote:
Hi Alan,
I have looked at it, but I do not know where to begin.?
?
Besides, it needs a PTO.? I do not have a 3D printer to
make the part.
?
I think one ham used a fix frequency oscillator in place
of the PTO.? I wonder what the frequency was.?? W1AW???
?
Or I use a different analog VFO that could be used
instead of a PTO.
?
73 Daniel KK4MRN
?
?
?
?
?
?
?
--
Ryan Flowers - W7RLF
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If budget is not an issue:
<>
FYI
--
chuck adams, aa7fo
QRP WAS 17m started Apr 2, 2025
WAS-17 QRP --> TX,FL,SC,GA,OK,AR,KS,AL,AZ,MN
PA,CA,CO,WI,NE,ID,IL,NC,NY,AL
MA
DXCC W,VE,JA,PY,ZL
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There's a complete YouTube series on building this, each module
has its own video, done by Dean KK4DAS. There are two folks who
are 3D printing the inductor assembly and making them available
just for the cost of postage though you will have to obtain the
brass screw and nut on your own.
73,
Steve AA7U
On 4/21/2025 8:37 AM, Daniel KK4MRN via
groups.io wrote:
toggle quoted message
Show quoted text
Hi Alan,
I have looked at it, but I do not know where to begin.?
?
Besides, it needs a PTO.? I do not have a 3D printer to make
the part.
?
I think one ham used a fix frequency oscillator in place of
the PTO.? I wonder what the frequency was.?? W1AW???
?
Or I use a different analog VFO that could be used instead of
a PTO.
?
73 Daniel KK4MRN
?
?
?
?
?
?
?
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With nothing more than some nylon bolts and nuts, some hot glue, and the required brass bolt, and maybe some PCB material for structure, you could make the knob stationary, and make the coil the thing that moves along a short track. Looks like a fun project! I've been wanting to build another DC RX, and the analog tuning is attractive. Maybe next winter. Too many projects lined up right now, one of which involves pistons, tires, and a winch.
On Mon, Apr 21, 2025 at 9:00?AM chuck adams via <chuck.adams.phd= [email protected]> wrote: If budget is not an issue:
<>
FYI
--
chuck adams, aa7fo
QRP WAS 17m started Apr 2, 2025
WAS-17 QRP --> TX,FL,SC,GA,OK,AR,KS,AL,AZ,MN
? ? ? ? ? ? ? ? PA,CA,CO,WI,NE,ID,IL,NC,NY,AL
? ? ? ? ? ? ? ? MA
DXCC? ? ? ? ? ?W,VE,JA,PY,ZL
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Hi Daniel,
This is a good place to start!
As Chuck mentioned you can get a nice PTO from
I already have one in stock that I was saving for just such a
project :)
In this post on SolderSmoke , Scott KQ4AOP, offers to print a
PTO form for others.
Send him an email and ask him if he can print one for you.
Good luck on your build Daniel!
73,
Alan, N8WQ
On 4/21/25 11:37, Daniel KK4MRN via
groups.io wrote:
toggle quoted message
Show quoted text
Hi Alan,
I have looked at it, but I do not know where to begin.?
?
Besides, it needs a PTO.? I do not have a 3D printer to make
the part.
?
I think one ham used a fix frequency oscillator in place of
the PTO.? I wonder what the frequency was.?? W1AW???
?
Or I use a different analog VFO that could be used instead of
a PTO.
?
73 Daniel KK4MRN
?
?
?
?
?
?
?
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Daniel?
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Hey don't let one or two stumbling blocks stop you from a project. You can start with a vxo just get in it working, and later change to a vfo or pto. Improvise a bit.?
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I am headed there now to glance at it.?
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Curt
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On Mon, Apr 21, 2025 at 09:00 AM, chuck adams wrote:
If budget is not an issue:
<>
FYI
That's a nifty little kit Chuck.
?
Dave
AA7EE
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There is a good chance that your local public library has a 3D printer that you might be able to use. If not at the library, ask around in your local ham club. That's one good reason to belong to a local club - and actually go to meetings and get to know a few people.
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However, there is no need for a 3D printed part, you can make the PTO with a glue stick:?
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When I first built my Soldersmoke challenge DCR, I wound the coil and then just put piece of steel into the coil (I did not have the right bold). The specific piece of steel I used was a screwdriver :) That showed that I could change the frequency, and I moved on to the BPF and the mixer.?
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Be creative, and come up with your own way of tuning the PTO.?
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de Karl Heinz - K5KHK
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Yes here is another one.?
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Worthwhile to experience a PTO at least once. I have two kits containing a PTO. NC2030 and 4state Cyclone.?
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But nothing sacred about using a PTO here except its simplicity.?
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Note the mixer, audio amp, filter and PTO could later be re-purposed into a superhet. Reminds me I have modules here to assemble said receiver.?
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A DC receiver has wonderful clean audio because there is no distortion from having a tight audio filter. Yes our ears can hear the difference.?
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Once in my professional work some agency paid for a very low distortion receiver. To my knowledge we made only one. Back then an A/D converter maybe 5 MHz and 12 or so bits was itself a large PC board. These were then the mainstays of our radars. To obtain low distortion our filter geek made a network to closely cancel the the amplitude and phase shape of his custom crystal filter. Oh it sounded wonderful listening to symphony and bluegrass music. Okay the CW sounded nice too. I got to both integrate and test it. I imagine any of the direct RF sampling receivers sound as good now for about 1000X less than that thing cost.?
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Experience and enjoy technology.?
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Curt wb8yyy?
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I have been working on the soldersmoke DC receiver in between batches of good weather and the weather has been unseasonably good, so it has been a little slow. I finished the audio amp a couple of days ago, and put all the boards together today. It works, more or less, but I miswired the transformer on the RF side of the double balanced mixer and have to fix it before I can declare victory. ?
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There is at least one person on the soldersmoke discord channel (invite is on the soldersmoke blog) who is making PTO forms for the price of a donation to support the soldersmoke podcast.? But it is pretty easy to build the variable inductor with a tube from a glue stick, too, like this...
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You can even start with an inductor wound on a toroid to make a fixed frequency version for testing, which I did before I had the variable inductor form.??
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73 Bill K7WXW
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I found solder smoke page on glue stick PTO. Just uses original glue and a toroid inside, coil around the glue stick. Looks like fun. Practical.?
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Hi everyone,
I think you have convinced me to build it.??
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So, I have a few more parts to get.? No biggie.? But I have everything else.?? I have an audio transformer for a crystal radio - just not sure if it will work in this situation.? Anyways, I found the BOM for the radio and the parts are in stock at mouser.?? And there is only one toroid I do not have - T50-6 - so another kitsandparts order.? That's ok.?? I kept going back and forth trying to figure out if I wanted that new UniVFO that Mike is offering - I may get it this time.? And get the 8.2V zener diode at mouser and those 100uh and 10uh inductors and that is it.
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Awhile back near the end of March, I sent a private message saying to Steve AA7U that I felt like I wanted to start over and create a Direct Conversion Receiver again but shake things up.? Well, he tried to convince me to do the Solder Smoke DC Receiver at the time.? I should have listened.?
Well, I finally came across the blog entry where they mention his radio and a photo of it.??
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Does it make a difference with 1N5819 vs. 1N5711?
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73 Daniel KK4MRN
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On Mon, Apr 21, 2025 at 05:34 PM, bill K7WXW wrote:
I have been working on the soldersmoke DC receiver in between batches of good weather and the weather has been unseasonably good, so it has been a little slow. I finished the audio amp a couple of days ago, and put all the boards together today. It works, more or less, but I miswired the transformer on the RF side of the double balanced mixer and have to fix it before I can declare victory. ?
?
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That's a neat-looking build Bill. I like the yellow trimmer capacitors in the BPF. I have a number of those that I got from Dan's Small Parts and Kits. They are 65pF, and Dan sells them for a dollar apiece. Not as cheap as the little 6mm economy trimcaps (including the "little brown buggers" to quote another group member!) but they are eminently more satisfying to use. They even have vanes that you can see - like a real variable capacitor! :D
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Hope you manage to get the DBM transformer rewired correctly.
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Dave
AA7EE
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Dave - I gotta say, getting a "neat-looking build" compliment from you made my day.? Thanks!? :)? ?The variable caps came from a stash of Tektronix parts that I accidently acquired when I bought this cabinet from a craiglist seller:
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I planned to use it for storing small parts and tools. I was quite surprised to find that it was already filled?with parts, even more so to realize that this set of rolling drawers was from Tektronix, from the days when the company had a shop that custom built stuff like this for its engineers, down to the cardboard boxes of different sizes that neatly nestled together in the drawers, like this:
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The fellow who sold it to me just wanted it out of his storage shed, so I got the whole thing for a hundred fifty bucks, which I was willing to pay for the cabinet, let alone the drawers of semiconductors, capacitors, nixie tubes, connectors, and assorted hardware it was stuffed with.? It was definitely the premier find from my days of haunting swapfests/craiglist/garagesales, looking for parts from the 70s, 80s, and 90s.??
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Cheers Bill K7WXW
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On Tue, Apr 22, 2025 at 08:51 PM, bill K7WXW wrote:
The fellow who sold it to me just wanted it out of his storage shed, so I got the whole thing for a hundred fifty bucks, which I was willing to pay for the cabinet, let alone the drawers of semiconductors, capacitors, nixie tubes, connectors, and assorted hardware it was stuffed with.? It was definitely the premier find from my days of haunting swapfests/craiglist/garagesales, looking for parts from the 70s, 80s, and 90s.
What a deal! That must have been fun, going through all the parts when you got home.
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Dave
AA7EE
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For the folks who built the soldersmoke dc receiver, which pto coil form did you print? I have some cycles on a nice 3d printer so I'd like to make one. Thanks!
73
Mike M Ku4qo
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You can download the STL file from the Soldersmoke discord server : ?
Or when you up to it, you could build a glue stick variant like I did : (based on Nick M0NTV project : )?
--
73 Lex PH2LB
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Alan N8WQ
Brian KB9BVN
bill K7WXW
Lex PH2LB