You can use WSPR for antenna testing for other modes. Just cut your output power to compensate for its power efficiency. Use at least 20dB less power than you would for CW, so if you're trying to see where you could get with a 5W CW signal, use 50mW instead. For SSB testing, drop your power even lower.
Well hell...you are telling me I could have done all this work in my basement and not the kitchen table?? Wow.? My wife will be happy to hear that. ? They really have a racket going to claim WSPR is good for antenna testing.? Do you have a chapter in your book on that?? You need to get the word out that is a worthless testing tool.
|
Well hell...you are telling me I could have done all this work in my basement and not the kitchen table? ?Wow. ?My wife will be happy to hear that. ? They really have a racket going to claim WSPR is good for antenna testing. ?Do you have a chapter in your book on that? ?You need to get the word out that is a worthless testing tool.
I am not designing my loop for 80 and 160. ?
I don¡¯t know what you ¡°get¡± or what your game is, but you make a lot of assumptions. ?it is amusing you show me a link to a controller that has an option for tracking its tuning to SWR and then you give me a story about how instability is insurmountable. ? Got it.
toggle quoted message
Show quoted text
On Dec 23, 2019, at 1:37 AM, Kirk Kleinschmidt via Groups.Io <sohosources@...> wrote:
? I get it. I'm not trying to stifle experimentation. I simply want to steer you toward the best resources.
Self-resonant mag loops made from strap (where the insulated ends overlap to provide the C to the loop's L), work best at VHF, where the high Q of the antenna still provides enough low-SWR bandwidth around the resonance point to minimize the effects of insulation-induced instabilities (temperature and humidity effects, too).
At 160 and 80 meters, however, when bandwidths are 3-5 kHz, more stable materials are beneficial or necessary.
Using WSPR to reference/define antenna performance is somewhat moot unless all you want to do is WSPR, at which point making a useful antenna becomes 40-dB "easier" than if you're trying to make an antenna that will be used for more conversational or more conventional modes. I congratulate you, but working DX via WSPR with any mag loop, even indoors or in the basement, is the norm and not the exception. If you run the numbers regarding propagation path loss, antenna gain, and the sensitivity of the WSPR demodulation process, you'll see that those distances are expected and on track. To make those QSOs via SSB, CW, or even PSK-31 takes a better-performing antenna/mag loop or more RF power, but it is still doable, even indoors. Many mag loop users, myself included, have made ocean-hopping SSB QSOs with mag loops sitting on the kitchen table while running QRP (5-10 W PEP) Again, scaling the numbers for power and the efficiency of the WSPR decoder, the events are approximately equivalent.
I don't know how to remove posted pix. Maybe it's not even possible.
Regardless, I'm just having a conversation here, so don't let me get in your way. I think what you're doing is fantastic. I have been doing my best to steer you toward the best methods and materials, but personal experimentation always earns my respect. Other readers, perhaps lacking your skills and determination, may want to know about what experts and experimenters have already discovered about how to make top-performing mag loops and mag loop autotuners. I have provided those links and references as part of our conversation.
Regards,
--Kirk, NT0Z ? Rochester, MN
My book, "Stealth Amateur Radio," is now available from
www.stealthamateur.com and on the Amazon Kindle (soon)
On Monday, December 23, 2019, 12:05:52 AM CST, Kurt Loken <kurt.loken@...> wrote:
Hello Kirk,
I think you might not be seeing what you think you are seeing.? I really made a big mistake posting here.? I wish I could delete my picture.? If anyone reading this knows how to delete photos from the group here, I would appreciate?help at making it so.? You get working on something and you want to share...but I'm not ready to share this stuff yet. ?
That "wire" on the side isn't a wire at all...it isn't what you think it is.? It will have zero effect on the loop...I guarantee it.? It is teflon and plastic not metal. ? There is NO METAL above the feed point other than those temporary push to fit connectors in the 3D printed cap.?
There are many choices that go into a design and one of them is cost.? Yes, a vacuum variable cannot be beat...though all the soldering of connections and all the peripherals (motors, shafts, etc.) that people seem to think are okay to put around them might lead to a debate on that subject.? There are some horrible designs on the internet...most of them have vac variables.? I am trying to make a low cost self tuning magloop with solid performance.? I think I can do that (including the electronics) for the cost of a single vac variable cap.? I would think this would interest someone who writes about stealth antennas.?
Teflon is not lossy in rf.? What material beats it?? Polystyrene?? Not much else. ?
The loop I'm making I also intend to use indoors, it is not meant to be used permanently mounted outside. ?
This map I show below were confirmed receipts yesterday of my 0.2W transmission from the loop in the picture sitting where the picture was taken...on my kitchen table.? I have reached hawaii and europe from that table using 0.2 watts on other days. ? No whip antenna would do that...feel free to try and let us know how it works out.
<Screen Shot 2019-12-21 at 1.36.55 PM.png>
Kurt-ae6uj ???
On Sun, Dec 22, 2019 at 11:08 PM Kirk Kleinschmidt via Groups.Io <sohosources= [email protected]> wrote: Sorry, Kurt,
A "daily driver" is an antenna that stays in service for long periods of time and is used daily (as opposed to something whipped together for one reason or another). It's a motor vehicle reference. I guess I'm getting old!
The Teflon data I'm remembering is/was in the mag loop archives when everything was hosted on Yahoo Groups (may now be at groups,io?). I don't have access right now, as I'm traveling, but perhaps someone else is on both lists who might?
Because of the unusual electric and magnetic properties encountered by mag loop materials (30,000 V at 30 amps, anyone?), almost nothing other than vacuum and air variables with no physical contacts (butterfly caps) emerges as stable and non-lossy.
These and many additional materials have been tested over the past 50 years, not just by hams, but by the military and commercial companies developing the mag loops are related stuff.
Leigh, VK5KLT, who has been intimately involved in military and commercial mag loop design (and the underlying science) for the past 50 years, is an accessible and approachable authority on all details of materials, feeding and construction. He's a regular on the Mag Loop list, and his papers are available on the web. He emails, too.
What does Lee say about Teflon? He says that vacuum and butterfly caps are better. :)? Good enough for me.
I have worked up various trombone/Teflon approaches over the years, but after I studied a lot more I set them aside.
In short, it works, but it's not ideal.
Also, if I'm remembering the photo correctly, you may have had some wires running up one side of the mag loop from bottom to top? Consider centering these on the main axis of the loop, as maintaining loop balance can also be critical (hence the practice of splitting the loop down the center when running wires, installing motors and caps, etc). With massive circulating currents on the loop, objects that are closer to one side of the loop than the other can mess things up. The same goes for items in the environment (wires, trees dog houses, cars, air conditioners, etc).
Regards,
--Kirk, NT0Z
My book, "Stealth Amateur Radio," is now available from
and on the Amazon Kindle (soon)
On Sunday, December 22, 2019, 10:36:30 PM CST, Kurt Loken < kurt.loken@...> wrote:
What do you mean by ¡°daily drivers?¡± ?Can you also share some data that Teflon is lossy at rf?
Thanks for the help.
Kurt? On Dec 22, 2019, at 9:26 PM, Kirk Kleinschmidt via Groups.Io <sohosources=[email protected]> wrote:
? Historically, Teflon hasn't been suitable for "daily drivers" over time, whether trombones or otherwise. It's fine for proof of concept, but it's far from ideal and it's lossy at RF. Not when used in "regular" antennas, but in magnetic loops, which are a whole nother breed.
What's been proven ideal? Vacuum and butterfly. That's pretty much it.
If you just want to crank out a "foxhole" loop, why not simply solder a short length or RG-8 coax (not foam dielectric, but the hard stuff) to the loop ends and cut the cable until the SWR analyzer says it's resonating on your chosen frequency? True, resonance moves around a bit with heat and humidity, but for single-frequency work it has been successfully used. And at 20 meters and up you'll have a few kHz of resonance to play around in.
I'm not trying to stifle innovation, but as an experienced mag loop builder and user (30 years now), I know that all of the things you're noodling around with have been tried before. The mag loop groups have treasure troves that detail what works and what doesn't. And of course, Youtube is filled with "revolutionary" loops that "work" after a fashion but absolutely don't work anywhere near as well as they could.
It takes about the same amount of farting around to make a mag loop that "works" as it does to use proven methods that are known to "work well" or define the state of the art.
Vacuum and Butterfly. Sounds like a country song! Or a mantra.
BTW, if you want an awesome autotuner designed for mag loops, complete with global temperature compensation, CAT and SWR inputs, and lots of other goodies, check out Loftur's masterpiece at:
Best of luck,
--Kirk, NT0Z
My book, "Stealth Amateur Radio," is now available from
and on the Amazon Kindle (soon)
On Sunday, December 22, 2019, 5:54:16 PM CST, Jerry Gaffke via Groups.Io <jgaffke= [email protected]> wrote:
Yes, if bandwidth is maybe 10khz, mechanical stability will be a real concern. My laminate thing, like a lot of mag loops I see, could be a bit floppy. But perhaps an advantage, distort the circular shape to tune it? Another thought about tuning, similar to a book cap, but uses FR4 board warping as a hinge: Have two PCB's perhaps 2" x 12" of one sided copper, 3 inches of copper removed from one end of each. The copper foil ends solder to each of the two PCB's at the ends that still have copper. Place one board over the other with teflon in between with copper facing copper, the 3" of removed copper on opposite ends. Two screws through one end hold them together firmly, the teflon well compressed here. The other end has some sort of screw with spring arrangement to adjust the distance between the two boards there If this is part of my foil on laminate antenna, could separate the two boards by removing those screws when coiling the antenna up tight for transport. nanoVNA here, but not yet dangerous with it.? Touch part of touch screen not working. Need to spend a full day just figuring out the menu, or get NanoVNA-Saver going. Also an AQRP VIA. Agree on needing something more than a DVM. Jerry On Sun, Dec 22, 2019 at 02:42 PM, Kurt Loken wrote:
The stability issue is real and controlling overlap with a motor is a challenge of engineering in and of itself. For myself I consider it a challenge and part of the fun.
Also...I have really come to believe that I don¡¯t know how anyone builds a magloop or experiments with them without a proper antenna analyzer. I would be lost without mine. Not sure if you have one, but they make experimenting easier.
<Screen Shot 2019-12-21 at 1.36.55 PM.png>
|
I get it. I'm not trying to stifle experimentation. I simply want to steer you toward the best resources.
Self-resonant mag loops made from strap (where the insulated ends overlap to provide the C to the loop's L), work best at VHF, where the high Q of the antenna still provides enough low-SWR bandwidth around the resonance point to minimize the effects of insulation-induced instabilities (temperature and humidity effects, too).
At 160 and 80 meters, however, when bandwidths are 3-5 kHz, more stable materials are beneficial or necessary.
Using WSPR to reference/define antenna performance is somewhat moot unless all you want to do is WSPR, at which point making a useful antenna becomes 40-dB "easier" than if you're trying to make an antenna that will be used for more conversational or more conventional modes. I congratulate you, but working DX via WSPR with any mag loop, even indoors or in the basement, is the norm and not the exception. If you run the numbers regarding propagation path loss, antenna gain, and the sensitivity of the WSPR demodulation process, you'll see that those distances are expected and on track. To make those QSOs via SSB, CW, or even PSK-31 takes a better-performing antenna/mag loop or more RF power, but it is still doable, even indoors. Many mag loop users, myself included, have made ocean-hopping SSB QSOs with mag loops sitting on the kitchen table while running QRP (5-10 W PEP) Again, scaling the numbers for power and the efficiency of the WSPR decoder, the events are approximately equivalent.
I don't know how to remove posted pix. Maybe it's not even possible.
Regardless, I'm just having a conversation here, so don't let me get in your way. I think what you're doing is fantastic. I have been doing my best to steer you toward the best methods and materials, but personal experimentation always earns my respect. Other readers, perhaps lacking your skills and determination, may want to know about what experts and experimenters have already discovered about how to make top-performing mag loops and mag loop autotuners. I have provided those links and references as part of our conversation.
Regards,
--Kirk, NT0Z ? Rochester, MN
My book, "Stealth Amateur Radio," is now available from
www.stealthamateur.com and on the Amazon Kindle (soon)
On Monday, December 23, 2019, 12:05:52 AM CST, Kurt Loken <kurt.loken@...> wrote:
Hello Kirk,
I think you might not be seeing what you think you are seeing.? I really made a big mistake posting here.? I wish I could delete my picture.? If anyone reading this knows how to delete photos from the group here, I would appreciate?help at making it so.? You get working on something and you want to share...but I'm not ready to share this stuff yet. ?
That "wire" on the side isn't a wire at all...it isn't what you think it is.? It will have zero effect on the loop...I guarantee it.? It is teflon and plastic not metal. ? There is NO METAL above the feed point other than those temporary push to fit connectors in the 3D printed cap.?
There are many choices that go into a design and one of them is cost.? Yes, a vacuum variable cannot be beat...though all the soldering of connections and all the peripherals (motors, shafts, etc.) that people seem to think are okay to put around them might lead to a debate on that subject.? There are some horrible designs on the internet...most of them have vac variables.? I am trying to make a low cost self tuning magloop with solid performance.? I think I can do that (including the electronics) for the cost of a single vac variable cap.? I would think this would interest someone who writes about stealth antennas.?
Teflon is not lossy in rf.? What material beats it?? Polystyrene?? Not much else. ?
The loop I'm making I also intend to use indoors, it is not meant to be used permanently mounted outside. ?
This map I show below were confirmed receipts yesterday of my 0.2W transmission from the loop in the picture sitting where the picture was taken...on my kitchen table.? I have reached hawaii and europe from that table using 0.2 watts on other days. ? No whip antenna would do that...feel free to try and let us know how it works out.
Kurt-ae6uj ???
On Sun, Dec 22, 2019 at 11:08 PM Kirk Kleinschmidt via Groups.Io <sohosources= [email protected]> wrote: Sorry, Kurt,
A "daily driver" is an antenna that stays in service for long periods of time and is used daily (as opposed to something whipped together for one reason or another). It's a motor vehicle reference. I guess I'm getting old!
The Teflon data I'm remembering is/was in the mag loop archives when everything was hosted on Yahoo Groups (may now be at groups,io?). I don't have access right now, as I'm traveling, but perhaps someone else is on both lists who might?
Because of the unusual electric and magnetic properties encountered by mag loop materials (30,000 V at 30 amps, anyone?), almost nothing other than vacuum and air variables with no physical contacts (butterfly caps) emerges as stable and non-lossy.
These and many additional materials have been tested over the past 50 years, not just by hams, but by the military and commercial companies developing the mag loops are related stuff.
Leigh, VK5KLT, who has been intimately involved in military and commercial mag loop design (and the underlying science) for the past 50 years, is an accessible and approachable authority on all details of materials, feeding and construction. He's a regular on the Mag Loop list, and his papers are available on the web. He emails, too.
What does Lee say about Teflon? He says that vacuum and butterfly caps are better. :)? Good enough for me.
I have worked up various trombone/Teflon approaches over the years, but after I studied a lot more I set them aside.
In short, it works, but it's not ideal.
Also, if I'm remembering the photo correctly, you may have had some wires running up one side of the mag loop from bottom to top? Consider centering these on the main axis of the loop, as maintaining loop balance can also be critical (hence the practice of splitting the loop down the center when running wires, installing motors and caps, etc). With massive circulating currents on the loop, objects that are closer to one side of the loop than the other can mess things up. The same goes for items in the environment (wires, trees dog houses, cars, air conditioners, etc).
Regards,
--Kirk, NT0Z
My book, "Stealth Amateur Radio," is now available from
and on the Amazon Kindle (soon)
On Sunday, December 22, 2019, 10:36:30 PM CST, Kurt Loken < kurt.loken@...> wrote:
What do you mean by ¡°daily drivers?¡± ?Can you also share some data that Teflon is lossy at rf?
Thanks for the help.
Kurt? On Dec 22, 2019, at 9:26 PM, Kirk Kleinschmidt via Groups.Io <sohosources=[email protected]> wrote:
? Historically, Teflon hasn't been suitable for "daily drivers" over time, whether trombones or otherwise. It's fine for proof of concept, but it's far from ideal and it's lossy at RF. Not when used in "regular" antennas, but in magnetic loops, which are a whole nother breed.
What's been proven ideal? Vacuum and butterfly. That's pretty much it.
If you just want to crank out a "foxhole" loop, why not simply solder a short length or RG-8 coax (not foam dielectric, but the hard stuff) to the loop ends and cut the cable until the SWR analyzer says it's resonating on your chosen frequency? True, resonance moves around a bit with heat and humidity, but for single-frequency work it has been successfully used. And at 20 meters and up you'll have a few kHz of resonance to play around in.
I'm not trying to stifle innovation, but as an experienced mag loop builder and user (30 years now), I know that all of the things you're noodling around with have been tried before. The mag loop groups have treasure troves that detail what works and what doesn't. And of course, Youtube is filled with "revolutionary" loops that "work" after a fashion but absolutely don't work anywhere near as well as they could.
It takes about the same amount of farting around to make a mag loop that "works" as it does to use proven methods that are known to "work well" or define the state of the art.
Vacuum and Butterfly. Sounds like a country song! Or a mantra.
BTW, if you want an awesome autotuner designed for mag loops, complete with global temperature compensation, CAT and SWR inputs, and lots of other goodies, check out Loftur's masterpiece at:
Best of luck,
--Kirk, NT0Z
My book, "Stealth Amateur Radio," is now available from
and on the Amazon Kindle (soon)
On Sunday, December 22, 2019, 5:54:16 PM CST, Jerry Gaffke via Groups.Io <jgaffke= [email protected]> wrote:
Yes, if bandwidth is maybe 10khz, mechanical stability will be a real concern. My laminate thing, like a lot of mag loops I see, could be a bit floppy. But perhaps an advantage, distort the circular shape to tune it? Another thought about tuning, similar to a book cap, but uses FR4 board warping as a hinge: Have two PCB's perhaps 2" x 12" of one sided copper, 3 inches of copper removed from one end of each. The copper foil ends solder to each of the two PCB's at the ends that still have copper. Place one board over the other with teflon in between with copper facing copper, the 3" of removed copper on opposite ends. Two screws through one end hold them together firmly, the teflon well compressed here. The other end has some sort of screw with spring arrangement to adjust the distance between the two boards there If this is part of my foil on laminate antenna, could separate the two boards by removing those screws when coiling the antenna up tight for transport. nanoVNA here, but not yet dangerous with it.? Touch part of touch screen not working. Need to spend a full day just figuring out the menu, or get NanoVNA-Saver going. Also an AQRP VIA. Agree on needing something more than a DVM. Jerry On Sun, Dec 22, 2019 at 02:42 PM, Kurt Loken wrote:
The stability issue is real and controlling overlap with a motor is a challenge of engineering in and of itself. For myself I consider it a challenge and part of the fun.
Also...I have really come to believe that I don¡¯t know how anyone builds a magloop or experiments with them without a proper antenna analyzer. I would be lost without mine. Not sure if you have one, but they make experimenting easier.
|
Hello Kirk,
I think you might not be seeing what you think you are seeing.? I really made a big mistake posting here.? I wish I could delete my picture.? If anyone reading this knows how to delete photos from the group here, I would appreciate?help at making it so.? You get working on something and you want to share...but I'm not ready to share this stuff yet. ?
That "wire" on the side isn't a wire at all...it isn't what you think it is.? It will have zero effect on the loop...I guarantee it.? It is teflon and plastic not metal. ? There is NO METAL above the feed point other than those temporary push to fit connectors in the 3D printed cap.?
There are many choices that go into a design and one of them is cost.? Yes, a vacuum variable cannot be beat...though all the soldering of connections and all the peripherals (motors, shafts, etc.) that people seem to think are okay to put around them might lead to a debate on that subject.? There are some horrible designs on the internet...most of them have vac variables.? I am trying to make a low cost self tuning magloop with solid performance.? I think I can do that (including the electronics) for the cost of a single vac variable cap.? I would think this would interest someone who writes about stealth antennas.?
Teflon is not lossy in rf.? What material beats it?? Polystyrene?? Not much else. ?
The loop I'm making I also intend to use indoors, it is not meant to be used permanently mounted outside. ?
This map I show below were confirmed receipts yesterday of my 0.2W transmission from the loop in the picture sitting where the picture was taken...on my kitchen table.? I have reached hawaii and europe from that table using 0.2 watts on other days. ? No whip antenna would do that...feel free to try and let us know how it works out.
Kurt-ae6uj ???
On Sun, Dec 22, 2019 at 11:08 PM Kirk Kleinschmidt via Groups.Io <sohosources= [email protected]> wrote: Sorry, Kurt,
A "daily driver" is an antenna that stays in service for long periods of time and is used daily (as opposed to something whipped together for one reason or another). It's a motor vehicle reference. I guess I'm getting old!
The Teflon data I'm remembering is/was in the mag loop archives when everything was hosted on Yahoo Groups (may now be at groups,io?). I don't have access right now, as I'm traveling, but perhaps someone else is on both lists who might?
Because of the unusual electric and magnetic properties encountered by mag loop materials (30,000 V at 30 amps, anyone?), almost nothing other than vacuum and air variables with no physical contacts (butterfly caps) emerges as stable and non-lossy.
These and many additional materials have been tested over the past 50 years, not just by hams, but by the military and commercial companies developing the mag loops are related stuff.
Leigh, VK5KLT, who has been intimately involved in military and commercial mag loop design (and the underlying science) for the past 50 years, is an accessible and approachable authority on all details of materials, feeding and construction. He's a regular on the Mag Loop list, and his papers are available on the web. He emails, too.
What does Lee say about Teflon? He says that vacuum and butterfly caps are better. :)? Good enough for me.
I have worked up various trombone/Teflon approaches over the years, but after I studied a lot more I set them aside.
In short, it works, but it's not ideal.
Also, if I'm remembering the photo correctly, you may have had some wires running up one side of the mag loop from bottom to top? Consider centering these on the main axis of the loop, as maintaining loop balance can also be critical (hence the practice of splitting the loop down the center when running wires, installing motors and caps, etc). With massive circulating currents on the loop, objects that are closer to one side of the loop than the other can mess things up. The same goes for items in the environment (wires, trees dog houses, cars, air conditioners, etc).
Regards,
--Kirk, NT0Z
My book, "Stealth Amateur Radio," is now available from
and on the Amazon Kindle (soon)
On Sunday, December 22, 2019, 10:36:30 PM CST, Kurt Loken < kurt.loken@...> wrote:
What do you mean by ¡°daily drivers?¡± ?Can you also share some data that Teflon is lossy at rf?
Thanks for the help.
Kurt? On Dec 22, 2019, at 9:26 PM, Kirk Kleinschmidt via Groups.Io <sohosources=[email protected]> wrote:
? Historically, Teflon hasn't been suitable for "daily drivers" over time, whether trombones or otherwise. It's fine for proof of concept, but it's far from ideal and it's lossy at RF. Not when used in "regular" antennas, but in magnetic loops, which are a whole nother breed.
What's been proven ideal? Vacuum and butterfly. That's pretty much it.
If you just want to crank out a "foxhole" loop, why not simply solder a short length or RG-8 coax (not foam dielectric, but the hard stuff) to the loop ends and cut the cable until the SWR analyzer says it's resonating on your chosen frequency? True, resonance moves around a bit with heat and humidity, but for single-frequency work it has been successfully used. And at 20 meters and up you'll have a few kHz of resonance to play around in.
I'm not trying to stifle innovation, but as an experienced mag loop builder and user (30 years now), I know that all of the things you're noodling around with have been tried before. The mag loop groups have treasure troves that detail what works and what doesn't. And of course, Youtube is filled with "revolutionary" loops that "work" after a fashion but absolutely don't work anywhere near as well as they could.
It takes about the same amount of farting around to make a mag loop that "works" as it does to use proven methods that are known to "work well" or define the state of the art.
Vacuum and Butterfly. Sounds like a country song! Or a mantra.
BTW, if you want an awesome autotuner designed for mag loops, complete with global temperature compensation, CAT and SWR inputs, and lots of other goodies, check out Loftur's masterpiece at:
Best of luck,
--Kirk, NT0Z
My book, "Stealth Amateur Radio," is now available from
and on the Amazon Kindle (soon)
On Sunday, December 22, 2019, 5:54:16 PM CST, Jerry Gaffke via Groups.Io <jgaffke= [email protected]> wrote:
Yes, if bandwidth is maybe 10khz, mechanical stability will be a real concern. My laminate thing, like a lot of mag loops I see, could be a bit floppy. But perhaps an advantage, distort the circular shape to tune it? Another thought about tuning, similar to a book cap, but uses FR4 board warping as a hinge: Have two PCB's perhaps 2" x 12" of one sided copper, 3 inches of copper removed from one end of each. The copper foil ends solder to each of the two PCB's at the ends that still have copper. Place one board over the other with teflon in between with copper facing copper, the 3" of removed copper on opposite ends. Two screws through one end hold them together firmly, the teflon well compressed here. The other end has some sort of screw with spring arrangement to adjust the distance between the two boards there If this is part of my foil on laminate antenna, could separate the two boards by removing those screws when coiling the antenna up tight for transport. nanoVNA here, but not yet dangerous with it.? Touch part of touch screen not working. Need to spend a full day just figuring out the menu, or get NanoVNA-Saver going. Also an AQRP VIA. Agree on needing something more than a DVM. Jerry On Sun, Dec 22, 2019 at 02:42 PM, Kurt Loken wrote:
The stability issue is real and controlling overlap with a motor is a challenge of engineering in and of itself. For myself I consider it a challenge and part of the fun.
Also...I have really come to believe that I don¡¯t know how anyone builds a magloop or experiments with them without a proper antenna analyzer. I would be lost without mine. Not sure if you have one, but they make experimenting easier.
|
I too am curious on the details of why teflon is not a good choice.
If so, homebrew air variable caps could work, they just have to be?
big enough for a suitable air gap.
It's a hobby, and an opportunity to learn.
If I just wanted to communicate a message with stuff I buy, I'd use a cell phone.
Or write a post to some web forum.
Jerry
|
Sorry, Kurt,
A "daily driver" is an antenna that stays in service for long periods of time and is used daily (as opposed to something whipped together for one reason or another). It's a motor vehicle reference. I guess I'm getting old!
The Teflon data I'm remembering is/was in the mag loop archives when everything was hosted on Yahoo Groups (may now be at groups,io?). I don't have access right now, as I'm traveling, but perhaps someone else is on both lists who might?
Because of the unusual electric and magnetic properties encountered by mag loop materials (30,000 V at 30 amps, anyone?), almost nothing other than vacuum and air variables with no physical contacts (butterfly caps) emerges as stable and non-lossy.
These and many additional materials have been tested over the past 50 years, not just by hams, but by the military and commercial companies developing the mag loops are related stuff.
Leigh, VK5KLT, who has been intimately involved in military and commercial mag loop design (and the underlying science) for the past 50 years, is an accessible and approachable authority on all details of materials, feeding and construction. He's a regular on the Mag Loop list, and his papers are available on the web. He emails, too.
What does Lee say about Teflon? He says that vacuum and butterfly caps are better. :)? Good enough for me.
I have worked up various trombone/Teflon approaches over the years, but after I studied a lot more I set them aside.
In short, it works, but it's not ideal.
Also, if I'm remembering the photo correctly, you may have had some wires running up one side of the mag loop from bottom to top? Consider centering these on the main axis of the loop, as maintaining loop balance can also be critical (hence the practice of splitting the loop down the center when running wires, installing motors and caps, etc). With massive circulating currents on the loop, objects that are closer to one side of the loop than the other can mess things up. The same goes for items in the environment (wires, trees dog houses, cars, air conditioners, etc).
Regards,
--Kirk, NT0Z
My book, "Stealth Amateur Radio," is now available from
www.stealthamateur.com and on the Amazon Kindle (soon)
On Sunday, December 22, 2019, 10:36:30 PM CST, Kurt Loken <kurt.loken@...> wrote:
What do you mean by ¡°daily drivers?¡± ?Can you also share some data that Teflon is lossy at rf?
Thanks for the help.
Kurt?
On Dec 22, 2019, at 9:26 PM, Kirk Kleinschmidt via Groups.Io <sohosources@...> wrote:
? Historically, Teflon hasn't been suitable for "daily drivers" over time, whether trombones or otherwise. It's fine for proof of concept, but it's far from ideal and it's lossy at RF. Not when used in "regular" antennas, but in magnetic loops, which are a whole nother breed.
What's been proven ideal? Vacuum and butterfly. That's pretty much it.
If you just want to crank out a "foxhole" loop, why not simply solder a short length or RG-8 coax (not foam dielectric, but the hard stuff) to the loop ends and cut the cable until the SWR analyzer says it's resonating on your chosen frequency? True, resonance moves around a bit with heat and humidity, but for single-frequency work it has been successfully used. And at 20 meters and up you'll have a few kHz of resonance to play around in.
I'm not trying to stifle innovation, but as an experienced mag loop builder and user (30 years now), I know that all of the things you're noodling around with have been tried before. The mag loop groups have treasure troves that detail what works and what doesn't. And of course, Youtube is filled with "revolutionary" loops that "work" after a fashion but absolutely don't work anywhere near as well as they could.
It takes about the same amount of farting around to make a mag loop that "works" as it does to use proven methods that are known to "work well" or define the state of the art.
Vacuum and Butterfly. Sounds like a country song! Or a mantra.
BTW, if you want an awesome autotuner designed for mag loops, complete with global temperature compensation, CAT and SWR inputs, and lots of other goodies, check out Loftur's masterpiece at:
Best of luck,
--Kirk, NT0Z
My book, "Stealth Amateur Radio," is now available from
www.stealthamateur.com and on the Amazon Kindle (soon)
On Sunday, December 22, 2019, 5:54:16 PM CST, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
Yes, if bandwidth is maybe 10khz, mechanical stability will be a real concern. My laminate thing, like a lot of mag loops I see, could be a bit floppy. But perhaps an advantage, distort the circular shape to tune it? Another thought about tuning, similar to a book cap, but uses FR4 board warping as a hinge: Have two PCB's perhaps 2" x 12" of one sided copper, 3 inches of copper removed from one end of each. The copper foil ends solder to each of the two PCB's at the ends that still have copper. Place one board over the other with teflon in between with copper facing copper, the 3" of removed copper on opposite ends. Two screws through one end hold them together firmly, the teflon well compressed here. The other end has some sort of screw with spring arrangement to adjust the distance between the two boards there If this is part of my foil on laminate antenna, could separate the two boards by removing those screws when coiling the antenna up tight for transport. nanoVNA here, but not yet dangerous with it.? Touch part of touch screen not working. Need to spend a full day just figuring out the menu, or get NanoVNA-Saver going. Also an AQRP VIA. Agree on needing something more than a DVM. Jerry On Sun, Dec 22, 2019 at 02:42 PM, Kurt Loken wrote:
The stability issue is real and controlling overlap with a motor is a challenge of engineering in and of itself. For myself I consider it a challenge and part of the fun.
Also...I have really come to believe that I don¡¯t know how anyone builds a magloop or experiments with them without a proper antenna analyzer. I would be lost without mine. Not sure if you have one, but they make experimenting easier.
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That controller you link to is similar to what I have in mind...but an iPhone would be the interface to the user.
...but when I have someone with 30 years of knowledges telling me to give up...I¡¯m at a loss of what to do. ? Am I wasting my time with the idea of building anything in my own? ?Can¡¯t I just buy a commercial loop and save a lot of trouble. ?I think so. ?
Buy wire...hang a dipole.
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On Dec 22, 2019, at 10:36 PM, Kurt Loken via Groups.Io <kurt.loken@...> wrote: ? What do you mean by ¡°daily drivers?¡± ?Can you also share some data that Teflon is lossy at rf?
Thanks for the help.
Kurt? On Dec 22, 2019, at 9:26 PM, Kirk Kleinschmidt via Groups.Io <sohosources@...> wrote:
? Historically, Teflon hasn't been suitable for "daily drivers" over time, whether trombones or otherwise. It's fine for proof of concept, but it's far from ideal and it's lossy at RF. Not when used in "regular" antennas, but in magnetic loops, which are a whole nother breed.
What's been proven ideal? Vacuum and butterfly. That's pretty much it.
If you just want to crank out a "foxhole" loop, why not simply solder a short length or RG-8 coax (not foam dielectric, but the hard stuff) to the loop ends and cut the cable until the SWR analyzer says it's resonating on your chosen frequency? True, resonance moves around a bit with heat and humidity, but for single-frequency work it has been successfully used. And at 20 meters and up you'll have a few kHz of resonance to play around in.
I'm not trying to stifle innovation, but as an experienced mag loop builder and user (30 years now), I know that all of the things you're noodling around with have been tried before. The mag loop groups have treasure troves that detail what works and what doesn't. And of course, Youtube is filled with "revolutionary" loops that "work" after a fashion but absolutely don't work anywhere near as well as they could.
It takes about the same amount of farting around to make a mag loop that "works" as it does to use proven methods that are known to "work well" or define the state of the art.
Vacuum and Butterfly. Sounds like a country song! Or a mantra.
BTW, if you want an awesome autotuner designed for mag loops, complete with global temperature compensation, CAT and SWR inputs, and lots of other goodies, check out Loftur's masterpiece at:
Best of luck,
--Kirk, NT0Z
My book, "Stealth Amateur Radio," is now available from
www.stealthamateur.com and on the Amazon Kindle (soon)
On Sunday, December 22, 2019, 5:54:16 PM CST, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
Yes, if bandwidth is maybe 10khz, mechanical stability will be a real concern. My laminate thing, like a lot of mag loops I see, could be a bit floppy. But perhaps an advantage, distort the circular shape to tune it? Another thought about tuning, similar to a book cap, but uses FR4 board warping as a hinge: Have two PCB's perhaps 2" x 12" of one sided copper, 3 inches of copper removed from one end of each. The copper foil ends solder to each of the two PCB's at the ends that still have copper. Place one board over the other with teflon in between with copper facing copper, the 3" of removed copper on opposite ends. Two screws through one end hold them together firmly, the teflon well compressed here. The other end has some sort of screw with spring arrangement to adjust the distance between the two boards there If this is part of my foil on laminate antenna, could separate the two boards by removing those screws when coiling the antenna up tight for transport. nanoVNA here, but not yet dangerous with it.? Touch part of touch screen not working. Need to spend a full day just figuring out the menu, or get NanoVNA-Saver going. Also an AQRP VIA. Agree on needing something more than a DVM. Jerry On Sun, Dec 22, 2019 at 02:42 PM, Kurt Loken wrote:
The stability issue is real and controlling overlap with a motor is a challenge of engineering in and of itself. For myself I consider it a challenge and part of the fun.
Also...I have really come to believe that I don¡¯t know how anyone builds a magloop or experiments with them without a proper antenna analyzer. I would be lost without mine. Not sure if you have one, but they make experimenting easier.
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Re: Group Introduction: If you're going to post on the group, reply here!
Hi John,? Welcome to the group! I have info on my site (link below in sig) about putting the BITX40 on USB with digital. If you need a hand at all, let me know :)? Aside from those two mods, you have to run the VFO in positive offset instead of negative, or else change the BFO frequency.? --
Ryan Flowers W7RLF
https://miscdotgeek.com
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Re: Group Introduction: If you're going to post on the group, reply here!
Hello,
Just discovered this group.? I do operate JS8call qrp often and also have a BITX-40 that I've not yet assembled.? Hoping to correct that soon.? I'd like to set it up for USB and use it as a digital rig.
John
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Sorry guys,
I posted the copies here without permission so I need to remove them.? Please google online yourself if you want to read them.
73,
Mark.
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What do you mean by ¡°daily drivers?¡± ?Can you also share some data that Teflon is lossy at rf?
Thanks for the help.
Kurt?
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On Dec 22, 2019, at 9:26 PM, Kirk Kleinschmidt via Groups.Io <sohosources@...> wrote:
? Historically, Teflon hasn't been suitable for "daily drivers" over time, whether trombones or otherwise. It's fine for proof of concept, but it's far from ideal and it's lossy at RF. Not when used in "regular" antennas, but in magnetic loops, which are a whole nother breed.
What's been proven ideal? Vacuum and butterfly. That's pretty much it.
If you just want to crank out a "foxhole" loop, why not simply solder a short length or RG-8 coax (not foam dielectric, but the hard stuff) to the loop ends and cut the cable until the SWR analyzer says it's resonating on your chosen frequency? True, resonance moves around a bit with heat and humidity, but for single-frequency work it has been successfully used. And at 20 meters and up you'll have a few kHz of resonance to play around in.
I'm not trying to stifle innovation, but as an experienced mag loop builder and user (30 years now), I know that all of the things you're noodling around with have been tried before. The mag loop groups have treasure troves that detail what works and what doesn't. And of course, Youtube is filled with "revolutionary" loops that "work" after a fashion but absolutely don't work anywhere near as well as they could.
It takes about the same amount of farting around to make a mag loop that "works" as it does to use proven methods that are known to "work well" or define the state of the art.
Vacuum and Butterfly. Sounds like a country song! Or a mantra.
BTW, if you want an awesome autotuner designed for mag loops, complete with global temperature compensation, CAT and SWR inputs, and lots of other goodies, check out Loftur's masterpiece at:
Best of luck,
--Kirk, NT0Z
My book, "Stealth Amateur Radio," is now available from
www.stealthamateur.com and on the Amazon Kindle (soon)
On Sunday, December 22, 2019, 5:54:16 PM CST, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
Yes, if bandwidth is maybe 10khz, mechanical stability will be a real concern. My laminate thing, like a lot of mag loops I see, could be a bit floppy. But perhaps an advantage, distort the circular shape to tune it? Another thought about tuning, similar to a book cap, but uses FR4 board warping as a hinge: Have two PCB's perhaps 2" x 12" of one sided copper, 3 inches of copper removed from one end of each. The copper foil ends solder to each of the two PCB's at the ends that still have copper. Place one board over the other with teflon in between with copper facing copper, the 3" of removed copper on opposite ends. Two screws through one end hold them together firmly, the teflon well compressed here. The other end has some sort of screw with spring arrangement to adjust the distance between the two boards there If this is part of my foil on laminate antenna, could separate the two boards by removing those screws when coiling the antenna up tight for transport. nanoVNA here, but not yet dangerous with it.? Touch part of touch screen not working. Need to spend a full day just figuring out the menu, or get NanoVNA-Saver going. Also an AQRP VIA. Agree on needing something more than a DVM. Jerry On Sun, Dec 22, 2019 at 02:42 PM, Kurt Loken wrote:
The stability issue is real and controlling overlap with a motor is a challenge of engineering in and of itself. For myself I consider it a challenge and part of the fun.
Also...I have really come to believe that I don¡¯t know how anyone builds a magloop or experiments with them without a proper antenna analyzer. I would be lost without mine. Not sure if you have one, but they make experimenting easier.
|
Historically, Teflon hasn't been suitable for "daily drivers" over time, whether trombones or otherwise. It's fine for proof of concept, but it's far from ideal and it's lossy at RF. Not when used in "regular" antennas, but in magnetic loops, which are a whole nother breed.
What's been proven ideal? Vacuum and butterfly. That's pretty much it.
If you just want to crank out a "foxhole" loop, why not simply solder a short length or RG-8 coax (not foam dielectric, but the hard stuff) to the loop ends and cut the cable until the SWR analyzer says it's resonating on your chosen frequency? True, resonance moves around a bit with heat and humidity, but for single-frequency work it has been successfully used. And at 20 meters and up you'll have a few kHz of resonance to play around in.
I'm not trying to stifle innovation, but as an experienced mag loop builder and user (30 years now), I know that all of the things you're noodling around with have been tried before. The mag loop groups have treasure troves that detail what works and what doesn't. And of course, Youtube is filled with "revolutionary" loops that "work" after a fashion but absolutely don't work anywhere near as well as they could.
It takes about the same amount of farting around to make a mag loop that "works" as it does to use proven methods that are known to "work well" or define the state of the art.
Vacuum and Butterfly. Sounds like a country song! Or a mantra.
BTW, if you want an awesome autotuner designed for mag loops, complete with global temperature compensation, CAT and SWR inputs, and lots of other goodies, check out Loftur's masterpiece at:
Best of luck,
--Kirk, NT0Z
My book, "Stealth Amateur Radio," is now available from
www.stealthamateur.com and on the Amazon Kindle (soon)
On Sunday, December 22, 2019, 5:54:16 PM CST, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
Yes, if bandwidth is maybe 10khz, mechanical stability will be a real concern.
My laminate thing, like a lot of mag loops I see, could be a bit floppy.
But perhaps an advantage, distort the circular shape to tune it?
Another thought about tuning, similar to a book cap, but uses FR4 board warping as a hinge:
Have two PCB's perhaps 2" x 12" of one sided copper, 3 inches of copper removed from one end of each.
The copper foil ends solder to each of the two PCB's at the ends that still have copper.
Place one board over the other with teflon in between with copper facing copper, the 3" of removed copper on opposite ends.
Two screws through one end hold them together firmly, the teflon well compressed here.
The other end has some sort of screw with spring arrangement to adjust the distance between the two boards there
If this is part of my foil on laminate antenna, could separate the two boards by removing those screws
when coiling the antenna up tight for transport.
nanoVNA here, but not yet dangerous with it.? Touch part of touch screen not working.
Need to spend a full day just figuring out the menu, or get NanoVNA-Saver going.
Also an AQRP VIA.
Agree on needing something more than a DVM.
Jerry
On Sun, Dec 22, 2019 at 02:42 PM, Kurt Loken wrote:
The stability issue is real and controlling overlap with a motor is a challenge of engineering in and of itself. For myself I consider it a challenge and part of the fun.
Also...I have really come to believe that I don¡¯t know how anyone builds a magloop or experiments with them without a proper antenna analyzer. I would be lost without mine. Not sure if you have one, but they make experimenting easier.
|
Hello Jerry,
My 3D printed cap isn¡¯t wholly dissimilar to what you describe. I think the stability issue could be mitigated by having an overlap system rather than a hinge but that causes complications because the diameter of the main loop is always going to change. One other thing I did consider with my cap is heat dissipation. What I ended up with is Teflon not just between but also around the overlapping ends. I would have rather build the capacitor surrounding structure out of ceramic, but by the time I did it that way I may as well buy a vacuum variable because the cost would be high.
Having fun is what this hobby should be about. It is also about learning by doing. There is a huge amount of information on magloops and you should read it all, but there are some very ingrained ideas that have become dogma. Dogma can be good...it fills up the pews...and most of it is right.
How small can you make an antenna and still have it work like a champ? That is one thing that intrigued me. What is the definition of working like a champ? Reaching Europe from your kitchen table?
Have fun,
Kurt-ae6uj
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On Dec 22, 2019, at 5:54 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
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Yes, if bandwidth is maybe 10khz, mechanical stability will be a real concern.
My laminate thing, like a lot of mag loops I see, could be a bit floppy.
But perhaps an advantage, distort the circular shape to tune it?
Another thought about tuning, similar to a book cap, but uses FR4 board warping as a hinge:
Have two PCB's perhaps 2" x 12" of one sided copper, 3 inches of copper removed from one end of each.
The copper foil ends solder to each of the two PCB's at the ends that still have copper.
Place one board over the other with teflon in between with copper facing copper, the 3" of removed copper on opposite ends.
Two screws through one end hold them together firmly, the teflon well compressed here.
The other end has some sort of screw with spring arrangement to adjust the distance between the two boards there
If this is part of my foil on laminate antenna, could separate the two boards by removing those screws
when coiling the antenna up tight for transport.
nanoVNA here, but not yet dangerous with it.? Touch part of touch screen not working.
Need to spend a full day just figuring out the menu, or get NanoVNA-Saver going.
Also an AQRP VIA.
Agree on needing something more than a DVM.
Jerry
toggle quoted message
Show quoted text
On Sun, Dec 22, 2019 at 02:42 PM, Kurt Loken wrote:
The stability issue is real and controlling overlap with a motor is a challenge of engineering in and of itself. For myself I consider it a challenge and part of the fun.
Also...I have really come to believe that I don¡¯t know how anyone builds a magloop or experiments with them without a proper antenna analyzer. I would be lost without mine. Not sure if you have one, but they make experimenting easier.
|
The stability issue is real and controlling overlap with a motor is a challenge of engineering in and of itself. For myself I consider it a challenge and part of the fun.
Also...I have really come to believe that I don¡¯t know how anyone builds a magloop or experiments with them without a proper antenna analyzer. I would be lost without mine. Not sure if you have one, but they make experimenting easier.
Kurt-ae6uj
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On Dec 22, 2019, at 3:09 PM, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:
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Hi,
Typo there.? The journal issue which has the Elmer 101 book is QRPp Journal Volume 6 Number 3.? I just added a folder in the files section for copies of the journal and broke up volume 6 into its four seasonal issues for easier reading.
Cheers and 73,
Mark.
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I still like that laminate strip with a copper foil glued to it, a teflon sheet for the dielectric?where the foil
overlaps?to form a cap.? The overlap is held firmly in place by a couple bare FR4 boards bolted onto it.?
Perhaps add a gimmick cap of a couple teflon covered wires across the overlap cap for final adjustments.
So a very limited tuning range once you bolt down the overlap cap, but good enough for?
hitting a digital watering hole or perhaps keeping a schedule on a particular frequency.?
From an online calculator, skin effect at 14mhz is around 18um (well under a thousandth of an inch) for copper.
So a strip of moderately thin copper foil on laminate is sufficient, very lightweight, winds down to a small diameter.
There are ways to make a good variable cap, I like the trombone scheme of QST Nov 1994.
Could simplify that by going to 1.5" copper pipe with a gear drive motor inside, a 1.25" pipe
covered by a teflon sheet being pulled into it by a motor driven screw, the loop flexes a bit as
the 1.25" pipe moves.? But that would take a week, the laminate plus foil might be working in a day.?
Lots of mag loops using teflon, is that considered good enough for the capacitor dielectric?
Will using laminate for mechanical support have some undesired effect?
Jerry, KE7ER
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Re: Fwd Bias LEDs as Varicaps/Varactors
A bench test, sort of...
Using a 30m Rx**, 10.116 crystal?and a BB910 vs a small LED
I adjusted the LED bias?for about the same measured?C range as the BB910
The read-out on my FT-847 Rx and 25Hz filter.
BB910?? 10.113000? 10.110850?? .002150? (10V)
LED???????10.116000? 10.113140?? .002860? (6.5V)
I want to do some measurements with sig gen and scope. Off hand, though, I'd say the LED is useable as a Varactor.
**Simple SA612/LM386? built for WWV-10 and 30m
--
Chuck, W5USJ (ex K2OFN)
Point, Rains Co, TX? EM22cv
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Re: Fwd Bias LEDs as Varicaps/Varactors
There is of course a nice exponential relationship between forward voltage and current.
But forward current is much easier to measure.
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On Sun, Dec 22, 2019 at 07:15 AM, Jerry Gaffke wrote:
so what the graph is really showing is capacitance as a function of forward current.
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Mike ? Yep, I have seen it there and plan to use for my6 builders.? The PC boards are coming from China based on some Gerbers I found.? But I did see a book at one of the web sites so I thought I would ask.? It¡¯s a very nice thing that you have done putting those lesson up on your site, I appreciate it and your sited motivated me to get the boards built since you can not buy them anywhere and the PC board house that I used in China was cheap and very fast. ? Thanks so much for those lesson Mike ? Merry Christmas Steve NU0P ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Michael Maiorana
Sent: Sunday, December 22, 2019 5:19 AM
To: [email protected]
Subject: Re: [qrptech] Elmer 101 ? Steve, It's been over 20 years, but the original info is still on my qsl web page . You are welcome to print and use the info as you wish, just not for profit. ? On Sat, Dec 21, 2019, 10:03 PM stephen white <sswhite@...> wrote: I understand that their used to be a "Elmer 101" box available.? My little Builders group is going to be building SWxx's soon and would like to get a hold of this book for the builders.? Anyone have any ideas as to where I can get some of these or even one of these??? I have found all the Elmer 101 lessons on the net but if i can I would like to get the book.
Thanks
Steve NU0P
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Shirley Dulcey KE1L
Kirk Kleinschmidt, NT0Z
Chuck Carpenter