Wayne, Thank you.? I think that will work.?
73 Daniel KK4MRN
On Monday, April 21st, 2025 at 9:36 PM, Wayne McFee <nb6m@...> wrote:
Daniel,
A PTO VFO is a pretty simple beast, and the tuning coil arrangement is very easy and cheap to build.
I use some small pieces of double sided PCB material, a brass screw and brass nuts, a piece of plastic drinking straw and some enameled wire.
The vender Chuck mentions built his gadget based on what he saw in my instructions for the Tin Ear Receiver.
Personally, the fact that the brass screw moved in and out a quarter inch or so from the front panel was never an issue.
The first part of the attached article outlines how to build the tuning mechanism itself and the rest of a PTO VFO.
Hope it comes through OK.? Good luck with your build.
73,
Wayne NB6M
|
The link in the first paragraph will get you the schematic.? Also the web page
gives details on how to make the measurements.
I'm using a MingHe MHS-5200A signal generator good to 25MHz with output
from 5.0V down to less than 50mV, but the signal gets ugly at the low
output voltage.
Scope is a Rigol DS1054 50MHz 4 channel scope with 1GSample rate.
FYI
toggle quoted message
Show quoted text
On 4/21/25 20:52, Doug Hendricks via groups.io wrote: Could you post the circuit??? It looks very interesting, very interesting.? ?Doug
--
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,OH
DXCC W,VE,JA,PY,ZL
|
Could you post the circuit??? It looks very interesting,? very interesting.? ?Doug
|
Steve, AA7U, pointed the following circuit out to me and I just
had to build one.? Didn't take too long and it seems to work
nicely.? <>? Photo of my
build attached.
I have some calibration to do to make sure the I_C current is
10mA.? You're going to need one of these if the 1,000x2N3904s
I'm getting work out.? I've checked out 1,000x2N4401s @ 294MHz
and I'll give you pointers as soon as the final verdict is in.
Less than $20 USD for each batch and the vendor has 50,000,000 in
stock, so at $0.01 or so each that is quite an investment in
inventory.? The f_t above is subject to fine tuning on the
fixture is just below the 300MHz min in the spec sheet.
This is important as I finalize the ADC-40 transceiver BOM.
I found BF245B's for $0.025 each and should have them by
the end of the week.? With help from DeepSeek, we have
results better than what you would get with the 2N3819,
MPF102 or J310 jfets.? Film at 11.
That's end of my budget limit I set, but I have enough
for a lifetime.
So, get the paypal account ready and I'll help you spend
your money, if the measurements pan out.? With 2,000+
transistors, I'll not be building anything with an IC
in it unless it's in a kit.? :-)
Looking for others that have checked transistors thoroughly.
Open to new and improved ideas.
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,OH
DXCC W,VE,JA,PY,ZL
|
Re: SolderSmoke DC Receiver Challenge
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.?
?
|
Daniel,
A PTO VFO is a pretty simple beast, and the tuning coil arrangement is very easy and cheap to build.
I use some small pieces of double sided PCB material, a brass screw and brass nuts, a piece of plastic drinking straw and some enameled wire.
The vender Chuck mentions built his gadget based on what he saw in my instructions for the Tin Ear Receiver.
Personally, the fact that the brass screw moved in and out a quarter inch or so from the front panel was never an issue.
The first part of the attached article outlines how to build the tuning mechanism itself and the rest of a PTO VFO.
Hope it comes through OK.? Good luck with your build.
73,
Wayne NB6M
|
Re: SolderSmoke DC Receiver Challenge
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. ?
?
?
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...
?
?
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.??
?
73 Bill K7WXW
?
?
?
|
Re: SolderSmoke DC Receiver Challenge
Yes here is another one.?
?
?
Worthwhile to experience a PTO at least once. I have two kits containing a PTO. NC2030 and 4state Cyclone.?
?
But nothing sacred about using a PTO here except its simplicity.?
?
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.?
?
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.?
?
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.?
?
Experience and enjoy technology.?
?
Curt wb8yyy?
?
|
Re: SolderSmoke DC Receiver Challenge
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.
?
However, there is no need for a 3D printed part, you can make the PTO with a glue stick:?
?
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.?
?
Be creative, and come up with your own way of tuning the PTO.?
?
de Karl Heinz - K5KHK
|
Re: SolderSmoke DC Receiver Challenge
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
|
Re: SolderSmoke DC Receiver Challenge
Daniel?
?
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.?
?
I am headed there now to glance at it.?
?
Curt
?
|
Re: Honbay trimmers; I took one for the team
On Thu, Apr 10, 2025 at 03:34 PM, Doug W wrote:
Thank you for doing this.? In the same spirit, I ordered these yesterday ? I fully expect them to be junk but at $1.43 for 10 I threw them on an order to see what I get.?
?
?
I received my order today.? For less than the price of well anything these days these aren't any worse than I was expecting.? They are the same cheapo brown plastics ones that everyone sells.? My meter shows the expected values.? I may buy more in different value ranges before World War Fee kicks into full gear.
?
?
?
--
¡ì97.313?? Transmitter power standards.
(a) An amateur station must use the minimum transmitter power necessary to carry out the desired communications.
|
Re: SolderSmoke DC Receiver Challenge
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
?
?
?
?
?
?
?
|
Re: Source for 88 millihenry inductors?
The only ones I've found are potted and at ghastly prices.
?
I haven't seen the unpotted ones like in articles in articles
in over 45years.
?
?
Allison
?
|
Source for 88 millihenry inductors?
Does anyone know of a source for 88 millihenry (88 mH) inductors? These were originally used by the phone company on telephone lines, and then later repurposed for use in the passive audio filters designed by Ed, W3NQN (now a silent key).?
73,
Douglas KA2UPW/5
?
|
Steve R. sent me some mica caps rated at +-1% for use as
pseudo-standard for capacitance checks.? Thanks Steve.
I'm sending him some transistors for his effort.
Here is a comparison between his measurements using a
DE-5000, which seems to be popular and mine arrives
tomorrow, and a W8BH L/C meter made from a kit and
a LC200A which I bought years ago on ebay when they
were cheaper.? I gave up my AADE to a charter school.
The 5pF was marked +-0.5pF and not a 1% precision one.
FYI
MICA CAP?? DE-5000?? W8BN L/C meter?? LC200A
?? 5pF?????? 5.2???????? 4.381???????? 4.51
? 62pF????? 62.7??????? 62.20???????? 62.59
?160pF???? 161.2?????? 158.8???????? 159.8
?592pF???? 589.2?????? 578.2???????? 588.5
1000pF???? 997.1????? 1028????????? 1010
1300pF??? 1303.1????? 1289????????? 1309
I can do a video doing the measurements when
I get my DE-5000, but I'm too busy hanging
wall paper now.? :-)
My $400 USD budget for rebuilding the lab is
not at an end.? Let's hope that I don't have
to do a go fund me account to get more.? :-)
I get a brand new metal brake today for doing
the K7QO enclosure procedure for projects.
Life is good.
ciao,
--
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
|
Re: SolderSmoke DC Receiver Challenge
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
|
Re: SolderSmoke DC Receiver Challenge
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
?
?
?
?
?
?
?
|
Re: SolderSmoke DC Receiver Challenge
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
|
Re: SolderSmoke DC Receiver Challenge
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
|
bill K7WXW
Alan N8WQ
Brian KB9BVN