Examples of passive mixers are diodes and sometimes mosfet.? ?
?
Most common examples of active mixer are Gilbert Cell which is in the common ne602/sa612 which use an array of transistors or dual gate FET.?
?
Usually passive mixers are better performing but rigs like my SW40 using ne602 do not get swamped on my ordinary wire antennas.?
?
No inherent virtue for active mixers in qrp designs. At HF ordinary silicon diodes work well in passive mixers.?
?
Curt
?
|
Hello,
I remember some message on this group where someone said a DCR that was designed by Chuck Adams had an active mixer in it instead of a passive double balanced diode mixer as you would normally see.
?
Was it a home brewed design with only transistors, capacitors, resistors, and inductors/transformers wound on toroids?? Or something that included ICs or a commercial mixer??? I am hoping a home brewed design.
?
I am curious.
?
I am trying to read up in various books on mixers and I remembered a message on QRPTech where somebody said Chuck's mixer was an active mixer.
?
Thanks,
Daniel KK4MRN
?
?
|
Re: Source for 88 millihenry inductors?
Sorry for the off-topic. Consider using Sallen-Key active filters.
A couple of examples using BJTs rather than opamps are below.
Simply cascading 3 identical cells:
Calculated for Chebyshev 0.5dB response:
?
I tried using 1% resistors and 20% ceramic capacitors in my version. The response curve is not as nice as with opamps, but the sound is good nevertheless.
?
73, Mike AF7KR
?
|
It's a clever circuit alright, and I guess I'll have to give it a shot too. Some years back I was discussing how to measure Ft with Glen Weinweber.? I think he got a little further along than I did.???
More recently I thought I'd just try a plain vanilla amplifier and compare the responses of different transistors. It wouldn't tell me the Ft, but it would show me how a 2N2222 compares with a 2N5179, for instance, or how an unmarked?or house marked transistor compared to known types. I avoided reactances to keep it clean, except for the unavoidable coupling and bypass capacitors, and I also biased for?10 mA. The idea was to use the nanoVNA as the source and the detector.? It worked OK, I guess.
But this Wenzel circuit seems a lot cooler.? I assume when one port isn't being used, you'd put a 50 ohm terminator on it???
I can see using the nanoVNA again. The measurement at the CAL port should be flat, so you could just look at it once and record the dB value, then go to the OUT port and find the? frequency where the response curve has that value.
73
Nick, WA5BDU
On Tue, Apr 22, 2025 at 10:20?AM chuck adams via <chuck.adams.phd= [email protected]> wrote: Yep, it's a 5 ohm resistor in parallel.? The circuit on the web has two
10 ohm
resistors in parallel.
I'm thinking of going with a RF voltmeter instead of the scope.? I get some
'jitter' on the max voltage reading on the Rigol of about 5% or so and it
is irritating.
I'm here to share.
On 4/22/25 06:20, Michael Maiorana via wrote:
> Hi Chuck,
> That's an interesting circuit. It's hard to tell from your picture,
> but do you have two 51 ohm resistors in parallel to ground on the
> "CAL" pin? Or is that a 5 ohm resistor in parallel with 51 ohms?
> Since these two signals are 180 degrees out-of-phase, I wonder if you
> could put some sort of summing amplifier there, so you can just adjust
> the frequency until the LED goes out? Saves the need to break out the
> O-scope.
> Thanks for sharing
> 73
> Mike M.? KU4QO
>
> On Mon, Apr 21, 2025 at 11:48?PM chuck adams via
> <> <chuck.adams.phd=[email protected]> wrote:
>
>? ? ?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
>
>
>
>
>
>
--
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: LT Spice Alternatives
Not a direct answer to your question, but ... yes, LTspice can be tough but probably no more than any other true SPICE package. I've presenting an?introductory?talk on the subject at FDIM. I'm not a super "power user" though.
If you have an .asc file that's giving you problems, you can email it to me (include any models not part of the program) and I'll see if I can figure it out. Sometimes a second set of eyes can find a problem.
73
Nick, WA5BDU
Have been wrestling with LT Spice and the reticent LT Spice group* group mods. See other packages out there and wonder if I am missing something more friendly.?
?
Friendly recommendations greatly appreciated.
?
*Nice people but sort of engineers with a very low tolerance for dumb Biz Admin folks asking dumb questions about how to get the Spice models to display Bode plots and the eccentrics of plotting in general.
--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got worse."
|
Re: Source for 88 millihenry inductors?
I've been winding my own 88mH inductors on pot cores from Amidon using their PC-2213-77 cores.? For 88mH I think it took
about 100 turns.? The wire is wound on a bobbin, so it's not like putting turns on a toroid.? ?I stuck the bobbin on a pencil
and used a common pin stuck in the eraser as a Polish turns counter.? ?I've made inductors up to 100 mH - easy as pie.
?
The Amidon website provides info
?
?
?
KI4IO
Jerry W
Warrenton, VA?
|
Yep, it's a 5 ohm resistor in parallel.? The circuit on the web has two 10 ohm
resistors in parallel.
I'm thinking of going with a RF voltmeter instead of the scope.? I get some
'jitter' on the max voltage reading on the Rigol of about 5% or so and it
is irritating.
I'm here to share.
toggle quoted message
Show quoted text
On 4/22/25 06:20, Michael Maiorana via groups.io wrote: Hi Chuck,
That's an interesting circuit. It's hard to tell from your picture, but do you have two 51 ohm resistors in parallel to ground on the "CAL" pin? Or is that a 5 ohm resistor in parallel with 51 ohms?
Since these two signals are 180 degrees out-of-phase, I wonder if you could put some sort of summing amplifier there, so you can just adjust the frequency until the LED goes out? Saves the need to break out the O-scope.
Thanks for sharing
73
Mike M.? KU4QO
On Mon, Apr 21, 2025 at 11:48?PM chuck adams via groups.io <> <chuck.adams.phd@...> wrote:
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
--
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
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. ?
?
?
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
?
Hope you manage to get the DBM transformer rewired correctly.
?
Dave
AA7EE
|
i have a peak transistor tester, which gives me f_t but that little tester looks like a fun project and i have roughly a zillion 2N3904s, 2N2222s, etc that i could run through it, so build it i will.?
?
cheers
bill
|
Hi Chuck, That's an interesting circuit. It's hard to tell from your picture, but do you have two 51 ohm resistors in parallel to ground on the "CAL" pin? Or is that a 5 ohm resistor in parallel with 51 ohms?
Since these two signals are 180 degrees out-of-phase, I wonder if you could put some sort of summing amplifier there, so you can just adjust the frequency until the LED goes out? Saves the need to break out the O-scope.? Thanks for sharing 73 Mike M.? KU4QO
On Mon, Apr 21, 2025 at 11:48?PM chuck adams via <chuck.adams.phd= [email protected]> wrote: 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
Hi everyone,
I think you have convinced me to build it.??
?
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.
?
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.??
?
Does it make a difference with 1N5819 vs. 1N5711?
?
73 Daniel KK4MRN
|
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
|
Nick Kennedy
bill K7WXW
