Date   
Re: Availability of Mag Loop and other stuff...

Ian Reeve
 

Hi Arv,  Very useful information and so useful that they can be used any orientation,they are a option but as my amateur radio course tutor says....you need as much wire in the sky as you can get....as a stating point to good Hf receive.


From: BITX20@groups.io <BITX20@groups.io> on behalf of Arv Evans <arvid.evans@...>
Sent: Sunday, June 2, 2019 6:19:39 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Availability of Mag Loop and other stuff...
 
Antenna measurements are for the most part relative to some measured reference signal between
the antenna being tested and the remote reception point.  Antenna at the remote reception point
would seem to be immaterial as long as it does not change characteristics during the tests.  In most
antenna test ranges it is the device being tested that is rotated with the received signal at a fixed
point being measured.  This allows measurement and documentation of signal levels at various
angles of radiation.  Rotating or moving the receiving site is not necessary and would probably
invalidate the measurements. 

Small loop antennas are interesting for another reason.  They can be mounted and measured in
either horizontal or vertical position relative to the local ground plane, or at any angle in between. 
This gives one an idea of which propagation angle might be more advantageous, but only an
idea of that.  Propagation at later dates may totally invalidate any reference measurements that
have been made and published. 

My 2 pence worth. 

Arv
_._


On Sun, Jun 2, 2019 at 9:39 AM ajparent1/KB1GMX <kb1gmx@...> wrote:
Jack,

Not showing off, no one is paying for it.  However when someone claims a loop
that 1-2db below a EFHW (or a dipole) that's pretty close to saying my 10 year
old Tacoma can win at Indy.  In short, not likely or the Indy cars had an unusual
handicap, like no fuel and must be pushed by pit crew.   Reality is that the EFHW
is pointed in some random direction relative to the station and the loop is aimed
though its 3db beam width is likely far wider than the EFHW or a standard dipole
at reasonable height.  That makes its aim very wide where a 80-10 EFHW on
40M will at best have a pattern with a beam width that is narrow as its 1
wavelength long.   I can claim and prove my square loop on 6M at 7ft is better
than my portable 6M full wave length rectaangle loop at 25ft  by pointing the
edge of the loop to the station at distance as the front to side is easily 20db
down.  For that I'm at least the same horizontal polarization.  The square loop
under that condition is about 14db better however if the big loop is aligned its
4 db worse.  In short that proves the big loop does really work and also proves
the omnidiriectional square loop is superior when omnidirectional coverage
is required.

In short comparing it to any antenna without some form of controls and claiming
performance is at best meaningless.    A valid compare is a full size vertical with
elevated radials as it will have known gain and similar takeoff angles.

Loops are cool antennas but they are small antennas and they nominally will be
negative gain compared to any dipole.  Its the nature of antenna compromise.

Fyi: the testing part is to show how difficult it is to get meaningful real world
test data with any accuracy at HF because of distances and even local
surface propagation.   Modeled is of value but care must be taken to use a 
model that works with small loops and real grounds (NEC4.2 engine).

As to helpful.  Yes I want people to realize the limits of small antennas and
the claims sometimes made that are against all modeled data and practical
theory never minding prior works done to verify the models.  To that I see a
lot of suppliers and articles for loops making claims like this is the new
better sliced bread.  

I use loops and I do apply them as they have characteristics that make
them useful.  First being they are self contained antennas. The other
feature is the nulls and their insensitivity to close in electrostatic fields.
Its what they are good at even when they are full sized 1lambda loops.

Allison

Re: Availability of Mag Loop and other stuff...

Arv Evans
 

Ian

As much wire in the air as is physically possible is a good approach, as long as one has
many acres of open space to work with.  Loop antennas are effective enough for those of
us with HOA restrictions to get on the air, even if we have to hide the antenna in the attic. 
Loop antenna efficiency does increase with increasing size.  Size versus efficiency is a
trade-off that we sometimes have to live with. 

Small loops can be rotated in a small space and can even be rotated from vertical to
horizontal orientation, and anywhere in between.  Doing that with a 7 wavelength rhombic
antenna on 80 meters may be a little difficult.  8-)

Arv
_._


On Sun, Jun 2, 2019 at 11:34 AM Ian Reeve <ian.radioworkshop@...> wrote:
Hi Arv,  Very useful information and so useful that they can be used any orientation,they are a option but as my amateur radio course tutor says....you need as much wire in the sky as you can get....as a stating point to good Hf receive.


From: BITX20@groups.io <BITX20@groups.io> on behalf of Arv Evans <arvid.evans@...>
Sent: Sunday, June 2, 2019 6:19:39 PM
To: BITX20@groups.io
Subject: Re: [BITX20] Availability of Mag Loop and other stuff...
 
Antenna measurements are for the most part relative to some measured reference signal between
the antenna being tested and the remote reception point.  Antenna at the remote reception point
would seem to be immaterial as long as it does not change characteristics during the tests.  In most
antenna test ranges it is the device being tested that is rotated with the received signal at a fixed
point being measured.  This allows measurement and documentation of signal levels at various
angles of radiation.  Rotating or moving the receiving site is not necessary and would probably
invalidate the measurements. 

Small loop antennas are interesting for another reason.  They can be mounted and measured in
either horizontal or vertical position relative to the local ground plane, or at any angle in between. 
This gives one an idea of which propagation angle might be more advantageous, but only an
idea of that.  Propagation at later dates may totally invalidate any reference measurements that
have been made and published. 

My 2 pence worth. 

Arv
_._


On Sun, Jun 2, 2019 at 9:39 AM ajparent1/KB1GMX <kb1gmx@...> wrote:
Jack,

Not showing off, no one is paying for it.  However when someone claims a loop
that 1-2db below a EFHW (or a dipole) that's pretty close to saying my 10 year
old Tacoma can win at Indy.  In short, not likely or the Indy cars had an unusual
handicap, like no fuel and must be pushed by pit crew.   Reality is that the EFHW
is pointed in some random direction relative to the station and the loop is aimed
though its 3db beam width is likely far wider than the EFHW or a standard dipole
at reasonable height.  That makes its aim very wide where a 80-10 EFHW on
40M will at best have a pattern with a beam width that is narrow as its 1
wavelength long.   I can claim and prove my square loop on 6M at 7ft is better
than my portable 6M full wave length rectaangle loop at 25ft  by pointing the
edge of the loop to the station at distance as the front to side is easily 20db
down.  For that I'm at least the same horizontal polarization.  The square loop
under that condition is about 14db better however if the big loop is aligned its
4 db worse.  In short that proves the big loop does really work and also proves
the omnidiriectional square loop is superior when omnidirectional coverage
is required.

In short comparing it to any antenna without some form of controls and claiming
performance is at best meaningless.    A valid compare is a full size vertical with
elevated radials as it will have known gain and similar takeoff angles.

Loops are cool antennas but they are small antennas and they nominally will be
negative gain compared to any dipole.  Its the nature of antenna compromise.

Fyi: the testing part is to show how difficult it is to get meaningful real world
test data with any accuracy at HF because of distances and even local
surface propagation.   Modeled is of value but care must be taken to use a 
model that works with small loops and real grounds (NEC4.2 engine).

As to helpful.  Yes I want people to realize the limits of small antennas and
the claims sometimes made that are against all modeled data and practical
theory never minding prior works done to verify the models.  To that I see a
lot of suppliers and articles for loops making claims like this is the new
better sliced bread.  

I use loops and I do apply them as they have characteristics that make
them useful.  First being they are self contained antennas. The other
feature is the nulls and their insensitivity to close in electrostatic fields.
Its what they are good at even when they are full sized 1lambda loops.

Allison

Re: Availability of Mag Loop and other stuff...

iz oos
 

Maybe it would be easier to test if made for the 2m band and compare with a ground plane and a dipole at different heights.
It is interesting the link https://www.lnrprecision.com/store/W4OP-Loop-Antenna-p69633466 which deals with the efficiency of commercial small loops. If you can really obtain a small loop with a 50% efficiency I would be really interested to know more about it.


Il 02/giu/2019 19:20, "Arv Evans" <arvid.evans@...> ha scritto:
Antenna measurements are for the most part relative to some measured reference signal between
the antenna being tested and the remote reception point.  Antenna at the remote reception point
would seem to be immaterial as long as it does not change characteristics during the tests.  In most
antenna test ranges it is the device being tested that is rotated with the received signal at a fixed
point being measured.  This allows measurement and documentation of signal levels at various
angles of radiation.  Rotating or moving the receiving site is not necessary and would probably
invalidate the measurements. 

Small loop antennas are interesting for another reason.  They can be mounted and measured in
either horizontal or vertical position relative to the local ground plane, or at any angle in between. 
This gives one an idea of which propagation angle might be more advantageous, but only an
idea of that.  Propagation at later dates may totally invalidate any reference measurements that
have been made and published. 

My 2 pence worth. 

Arv
_._


On Sun, Jun 2, 2019 at 9:39 AM ajparent1/KB1GMX <kb1gmx@...> wrote:
Jack,

Not showing off, no one is paying for it.  However when someone claims a loop
that 1-2db below a EFHW (or a dipole) that's pretty close to saying my 10 year
old Tacoma can win at Indy.  In short, not likely or the Indy cars had an unusual
handicap, like no fuel and must be pushed by pit crew.   Reality is that the EFHW
is pointed in some random direction relative to the station and the loop is aimed
though its 3db beam width is likely far wider than the EFHW or a standard dipole
at reasonable height.  That makes its aim very wide where a 80-10 EFHW on
40M will at best have a pattern with a beam width that is narrow as its 1
wavelength long.   I can claim and prove my square loop on 6M at 7ft is better
than my portable 6M full wave length rectaangle loop at 25ft  by pointing the
edge of the loop to the station at distance as the front to side is easily 20db
down.  For that I'm at least the same horizontal polarization.  The square loop
under that condition is about 14db better however if the big loop is aligned its
4 db worse.  In short that proves the big loop does really work and also proves
the omnidiriectional square loop is superior when omnidirectional coverage
is required.

In short comparing it to any antenna without some form of controls and claiming
performance is at best meaningless.    A valid compare is a full size vertical with
elevated radials as it will have known gain and similar takeoff angles.

Loops are cool antennas but they are small antennas and they nominally will be
negative gain compared to any dipole.  Its the nature of antenna compromise.

Fyi: the testing part is to show how difficult it is to get meaningful real world
test data with any accuracy at HF because of distances and even local
surface propagation.   Modeled is of value but care must be taken to use a 
model that works with small loops and real grounds (NEC4.2 engine).

As to helpful.  Yes I want people to realize the limits of small antennas and
the claims sometimes made that are against all modeled data and practical
theory never minding prior works done to verify the models.  To that I see a
lot of suppliers and articles for loops making claims like this is the new
better sliced bread.  

I use loops and I do apply them as they have characteristics that make
them useful.  First being they are self contained antennas. The other
feature is the nulls and their insensitivity to close in electrostatic fields.
Its what they are good at even when they are full sized 1lambda loops.

Allison

Re: HFSignals poor business practices

John Cardoso
 

Hi Ashhar
Greetings from Canada, from an eighty-year-old retired electronics/electric professional engineer, hobbyist,  and radio ham.
Let me start by congratulating you,  Ashhar, for your dedication to and for the success of your work. It's great that you have made it available to old and new generations of smart radio enthusiasts. Great work. I mean it. Keep it up.
I was just disappointed by the lack of instructions/info with the kit and its poor presentation - a list of parts on a clearly torn half-sheet of paper, and an invoice; that was all I got.  And, pardon me to differ, also a bit disappointed by the quality of the parts that came with the board. As an Arduino hobbyist/project-builder, when I order stuff from China (through ebay) I expect "minimal" quality but, I confess, I was expecting a little better from HFSignals. I realize that some economic factors are involved, on both sides, that have to be considered.
This is a great group.  I have been following it for a while now. I also admire that you often take part in the discussions. Gives the rest of us the feeling that we are all in this together. Some of the guys here are tops, and I will be coming back for help, guidance, and learning. (Yes, old dogs can learn new tricks.)
I am not one to start or enjoy debates online. I did not want to start one. If I had given careful thought to my post, I probably wouldn't have done it. (BTW Ashhar you have some loyal and though supporters here. Ouch!)
My apologies if I hurt some sensitivities.  And my thanks to those who understood my main idea and took the time to write.
This will be my last post on this subject. Cheers to all. You are all doing great work!
73's

On 6/2/2019 2:37 AM, Ashhar Farhan wrote:
John,

You are refering to the BITX40 kit, rather than the uBITX. I entirely accept that the presentation could be better. I am working on updating the BITX40 documentation and it should be through in a week.
However, on quality, I have to be a little defensive. 
First, we use high grade components through out. Our toroids are from micrometals our encoders are original Bourn.
You mentioned the 'crappy' tiny ptt button and mic. Considering that our goal was to ship an entire SSB transceiver for well under the price of a standard radio mic, instead of not shipping any mic at all, chose to ship a very fine electret mic. It is a Panasonic that forms the main element. It has had very good on-air reviews.
The small ptt microswitch is what many mics have inside them. Just like there is no casing for the transceiver, there is no casing for the mic either.
All inductors are measured before they get on the PCB, crystals are matched. After assembly, each board is tested and signed.
As for the firmware, it ships with the latest version. If you would like more features, you can try this https://github.com/amunters/bitx40, it is a great piece of software engineering by a very talented ham.
If there are any specific places you get stuck, do ask on this group. We are an open community, open to self correction.

-f

PS the 0.1 uf is a spare to help you eliminate RFI. Depending upon how you wire up the BITX 40 and into what kind of enclosure, you may need to solder it across a control or not.

On Sun 2 Jun, 2019, 9:02 AM Arv Evans, <arvid.evans@...> wrote:
Ken, and others

John and myself have discussed this off-net.  Turns out that I may have miss-interpreted
his post.  He is well qualified and experienced.  He just posted some thoughts that
probably we have all had from time to time.  I probably over-reacted a bit. 

Arv  K7HKL
_._

On Sat, Jun 1, 2019 at 7:41 PM Ken Hansen <ken@...> wrote:
I'm curious on out the research you undertook before purchasing a Bitx40 that lead you to expect anything other than what you got.

Everything not on the PCB is really included for two reasons:

1) to enable someone without access to a well-stocked 'junk box' to complete the radio, and
2) minimize postage

I'm not sure what I'd change at HFSignals, except maybe include a somewhat more informative 'getting started' document, but it would have to be multi-lingual, since the market is truly world-wide.

Ken, N2VIP

On Jun 1, 2019, at 2:26 PM, John Cardoso <ve9pct@...> wrote:

I have been wishing to order a Bitx40 for a while now. Meanwhile, I have been reading the posters of this group from time to time. I kept reading about the problems people were having with the radios but, I think, I had to experience it myself.
Maybe I am just a sucker for punishment. But I did not expect the experience to be this bad.
The order was delivered on time. So far so good. The packaging was well done and strong as if it was expected to go through hell and come out unscathed.
The surprises came after - The quality of the components can't be any worse - very cheap and poor quality pots, a tiny push button for PTT (are you kidding me?), a lousy mic and a 0.1 uF capacitor that I still have no idea where it will go.
There were no instructions of any sort. Not even a link to a website where they could be found. One half-page of an 8X11 sheet of paper with a list of the contents (probably to save on expenses), and an invoice, was all that came with the parts. No even a mention on the version of the board and/or  software. What version is it being sold now, anyway?
The whole thing is crappy. Is this the way they do business in India or is it just a company that doesn't know how to do it?
This post will probably have some replies telling me that I should have known better. Maybe. For hackers they say?

Virus-free. www.avast.com

Re: mBITX Freq display off by 000.001.00

Liam
 

It could be an incorrect BFO setting. Try going into the menu and scroll to "Settings". Then enter and scroll to the BFO setting. Have the radio tuned to the correct display frequency of a station and adjust until you hear the voice at the right pitch. A wrong BFO setting will also inhibit others from hearing you. VK3YE has a video on it.

Re: HFSignals poor business practices

Bob Bennett
 

The essence of thus radio is that is the means to learning about how radios apr put together. From your comments you are😉. Farhan’s objective is to give us a project to ‘hack’.  Building 3 (well, one done and working, one done and I blew something and the 20 meter version 75% complete) has really taught me a lot about radios. When I see the thousands of dollars price tags on the big commercial rigs, I have a much meter understanding of what goes into a high end rig. I had the opportunity to meet and have dinner with him this past Hamvention. He is always working to improve his products. A note to him will always help him and his cooperative. 
   Here is a description of his operation taken from his web page:

  HF Signals is a small enterprise based out of Hyderabad, India, that works with a collective of workers. Each of the toroids is hand wound. This provides these working women with a livelihood. The assembled boards are then DC checked.  A final RF check and tune-up is performed to check the receiver’s sensitivity as well as transmitter’s output before being shipped. Each board is individually numbered.

Good luck

Bob Bennett NZ2Z 

Re: HFSignals poor business practices

Ashhar Farhan
 

Not at all, John,
We give and take criticism. The BITX circuit, software as well as the business practices of HF Signals are all 'open source'. Unless we get concrete criticism (good and bad) we wont mend ourselves. As I said before, BITX40 happens to be a neglected child of this group. I am working to soup it up, the documenation as well as mods. I am going to up the shipped  BITX40 software to Allard's, I hope everyone is fine with it.

73, f



On Sun, Jun 2, 2019 at 11:31 PM John Cardoso <ve9pct@...> wrote:

Hi Ashhar
Greetings from Canada, from an eighty-year-old retired electronics/electric professional engineer, hobbyist,  and radio ham.
Let me start by congratulating you,  Ashhar, for your dedication to and for the success of your work. It's great that you have made it available to old and new generations of smart radio enthusiasts. Great work. I mean it. Keep it up.
I was just disappointed by the lack of instructions/info with the kit and its poor presentation - a list of parts on a clearly torn half-sheet of paper, and an invoice; that was all I got.  And, pardon me to differ, also a bit disappointed by the quality of the parts that came with the board. As an Arduino hobbyist/project-builder, when I order stuff from China (through ebay) I expect "minimal" quality but, I confess, I was expecting a little better from HFSignals. I realize that some economic factors are involved, on both sides, that have to be considered.
This is a great group.  I have been following it for a while now. I also admire that you often take part in the discussions. Gives the rest of us the feeling that we are all in this together. Some of the guys here are tops, and I will be coming back for help, guidance, and learning. (Yes, old dogs can learn new tricks.)
I am not one to start or enjoy debates online. I did not want to start one. If I had given careful thought to my post, I probably wouldn't have done it. (BTW Ashhar you have some loyal and though supporters here. Ouch!)
My apologies if I hurt some sensitivities.  And my thanks to those who understood my main idea and took the time to write.
This will be my last post on this subject. Cheers to all. You are all doing great work!
73's

On 6/2/2019 2:37 AM, Ashhar Farhan wrote:
John,

You are refering to the BITX40 kit, rather than the uBITX. I entirely accept that the presentation could be better. I am working on updating the BITX40 documentation and it should be through in a week.
However, on quality, I have to be a little defensive. 
First, we use high grade components through out. Our toroids are from micrometals our encoders are original Bourn.
You mentioned the 'crappy' tiny ptt button and mic. Considering that our goal was to ship an entire SSB transceiver for well under the price of a standard radio mic, instead of not shipping any mic at all, chose to ship a very fine electret mic. It is a Panasonic that forms the main element. It has had very good on-air reviews.
The small ptt microswitch is what many mics have inside them. Just like there is no casing for the transceiver, there is no casing for the mic either.
All inductors are measured before they get on the PCB, crystals are matched. After assembly, each board is tested and signed.
As for the firmware, it ships with the latest version. If you would like more features, you can try this https://github.com/amunters/bitx40, it is a great piece of software engineering by a very talented ham.
If there are any specific places you get stuck, do ask on this group. We are an open community, open to self correction.

-f

PS the 0.1 uf is a spare to help you eliminate RFI. Depending upon how you wire up the BITX 40 and into what kind of enclosure, you may need to solder it across a control or not.

On Sun 2 Jun, 2019, 9:02 AM Arv Evans, <arvid.evans@...> wrote:
Ken, and others

John and myself have discussed this off-net.  Turns out that I may have miss-interpreted
his post.  He is well qualified and experienced.  He just posted some thoughts that
probably we have all had from time to time.  I probably over-reacted a bit. 

Arv  K7HKL
_._

On Sat, Jun 1, 2019 at 7:41 PM Ken Hansen <ken@...> wrote:
I'm curious on out the research you undertook before purchasing a Bitx40 that lead you to expect anything other than what you got.

Everything not on the PCB is really included for two reasons:

1) to enable someone without access to a well-stocked 'junk box' to complete the radio, and
2) minimize postage

I'm not sure what I'd change at HFSignals, except maybe include a somewhat more informative 'getting started' document, but it would have to be multi-lingual, since the market is truly world-wide.

Ken, N2VIP

On Jun 1, 2019, at 2:26 PM, John Cardoso <ve9pct@...> wrote:

I have been wishing to order a Bitx40 for a while now. Meanwhile, I have been reading the posters of this group from time to time. I kept reading about the problems people were having with the radios but, I think, I had to experience it myself.
Maybe I am just a sucker for punishment. But I did not expect the experience to be this bad.
The order was delivered on time. So far so good. The packaging was well done and strong as if it was expected to go through hell and come out unscathed.
The surprises came after - The quality of the components can't be any worse - very cheap and poor quality pots, a tiny push button for PTT (are you kidding me?), a lousy mic and a 0.1 uF capacitor that I still have no idea where it will go.
There were no instructions of any sort. Not even a link to a website where they could be found. One half-page of an 8X11 sheet of paper with a list of the contents (probably to save on expenses), and an invoice, was all that came with the parts. No even a mention on the version of the board and/or  software. What version is it being sold now, anyway?
The whole thing is crappy. Is this the way they do business in India or is it just a company that doesn't know how to do it?
This post will probably have some replies telling me that I should have known better. Maybe. For hackers they say?

Virus-free. www.avast.com

Re: Sunil cases

Mark Hatch
 

Not normal....  There are two sets of phono plugs. Didn't check, but perhaps only one interrupts the downstream flow? I used on the front panel the ones with the silver nuts. When I plugged them in, they shutoff the speaker. I am using their front panel boards.

73
Mark
AJ6CU

Re: Availability of Mag Loop and other stuff...

ajparent1/KB1GMX
 

Jack,

Not aimed at you personally that was a general comment on some of the other loop vendors
that came from nowhere.  After all at this point you not selling anything.  If you telling people
how to do it [book] that's experimental electronics and encouraged.  

As to getting HOA/restricted people back on the air a loop is a possible choice but far from
the only one.  It has potential for a quick trip to the park, hill or other areas where ambient
electrical noise is much lower and its desirable to have minimal setup time.   Usually the
limitation is lack of imagination and maybe understanding of antennas in general.  Antennas
do not have to look like antennas and they can be reasonably efficient with a small amount
of work.  The key element is to look at the box and not be limited by it.  The biggest thing I
see is everyone wants every band even the inactive ones.  Two maybe three bands with a
reasonable antenna is far easier and more likely to be enjoyed.  

And being 10db down from a "good" antenna is not a crime.  I've worked a lot of DX from the
mobile on 40M QRP SSB with a center loaded 8ft whip.  Efficient?  No they are legendary for
being terrible as in easily 10db or more down from a full size vertical.  However the mobile is not
unlike the HOA, we just add it has to work at 80mph and clear a 12.6ft bridge (we have
low ones here!) when mounted on a truck more than 4ft above the road with a crappy
ground (counterpoise maybe?).  

As to commentary on exogenous factors, when you quote dB and people look at it without
understanding or knowledge of those factors it can look better than it is.  Fact is and I
already said that you cannot control the external factors as it would cost dearly, having
done it for MIL applications and budget.

Also I think it was Arv that suggested scaling it for low VHF and that can be done to show if
correlation holds true but its a lot of work to make a scale model and  test it against a vertical
dipole. 

I've done that and it can be close (usually +-1db) and the amount of room needed is a back
yard without metal fences or aluminum siding as reflections will make you nuts. Reflections
can make for errors as in higher or lower gain that should be expected.   The test is RF
source to a vertical dipole and a second dipole at a distance of 10-20M at 2m will do ok
and you get a RX measurement that will be the reference.  Dipoles vertical or horizontal if
resonant are predictable in gain and behavior.  A pair of ELK log periodic antennas would
work well for this, they just have to be the same.  I've used 4 element yagis for 2m and
432 as test antennas as they are simple and easy to make.  In any case directional
antennas  make for fewer issues with weak signals and reflections.    Now substitute the
antenna under test and  get new reading.   How to get an accurate reading is easy, on the
TX side use maybe 20dbm (100mw) and an attenuator to radiate a signal to the RX and
then use the attenuator as adjust the signal to S9. install new antenna at the RX end and after
recording the attenuator before then adjust it for S9 again.  The difference is gain or loss.
A SA can make that easier but any detector can do the job if sensitive enough and has
selectivity to avoid offending signals.  I've used a AD8703 for that with an input tuned
circuit [bandpass] added to keep it from hearing FM broadcast stations.    Don't try this
at HF you will go insane or expend much treasure and going end to end to read or
adjust will wear you out.

Allison

Re: Availability of Mag Loop and other stuff...

ajparent1/KB1GMX
 

Iz oos.

To get to 50% just make it bigger.  The cost is more material and size plus higher Q
makes tuning fussy.   A 3M diameter will do for 20m and at 40M you need to be
about 8m which is getting large.

Allison

Re: Sunil cases

Sam Tedesco
 

Sunil responded. The audio amp only drives the internal speaker. If i bring internal speaker to front daughter board, it turns off with external plugged in. Hate to waste the audio amp. Might bring it over to the v4 board. Thanks for the help

Re: Pin Change Interrupt library

johnrof@...
 

https://github.com/GreyGnome/PinChangeInt

Re: Availability of Mag Loop and other stuff...

Kees T
 

Fellow Loopers, guess "BITX20" is where it's at

a few thoughts....

Definition of a SML
1)  Let's say we want to stay closer to a 1M Loop.....maybe 40" to 48" diameter which is "relatively portable".  
2) Goal is 80m to 10m

Select a Band(s)
3) For 80m we probably need 2 turns separated by 10 tubing diameters (my rule of thumb...what is yours ?)
4) A single loop for 40m to 20m is fine, 17m and up is TBD
5) Loop switching is TBD

AC Loop resistance (KEY parameter).
6) Lowest reasonable tubing material for lowest resistance.....Copper vs Aluminum. That info is widely available. Cost,
    weight, and availability tradeoffs. Aluminum hardline is readily available and very inexpensive used. Copper can cost
    quite a bit used or not. You need TIG welding for aluminum.
7) Lowest number of joints and lowest resistance joints....bolted, soldered, silver soldered, brazed, welded. Does anyone
    have some measurement data for say .....a 2" wide joint with a 1/2" overlap at 80m.  We're talking milliohms and less
    here......yes, it is important in order to increase efficiency. You need TIG welding for aluminum.
8) Tubing material shape, assume round tubing. The larger the better.....up to a point where you start having RF current
    flow interference. A large donut shape does not work well, neither does anything flimsy due to wind effects (In my
    opinion).
9) Flat strap "tubing". The high current density is in the outside edges of the strap, not across the full width of the strap, 
    so if the strap is thin, the material conductive properties come into play.....bigtime. 
10) Using several (5?, 7?) identical hardline (cheap) loops as a sturdy form, cover them with thin copper sheeting, say 10"
    wide and running along the circumference of the loop. Curved (cupped) a little in the center. Do not spiral wind the
    copper sheeting due to the resultant seams. The idea here is to force the RF current density to the "wide" outside side of
    the copper. The other idea here is no serial seams except at the ends. A seam running the full inside diameter is OK and
    minimize copper sheeting wrinkles. Attach 1ft ? copper plates at the ends for the capacitor. (just some ideas).  Air
    spacing or Teflon sheeting for the dielectric.

The Capacitor
11) Many tradeoffs on the capacitor. One full range capacitor or several switched capacitors and a smaller "trimmer".....but
    again all contacts are going to add to the overall loop resistance and switching implementation will not be simple.

The Coupler

12) Allow for BOTH rotation of the coil and movement relative to the loop circumference.  

The Testing
13) I would recommend that someone in your group buy a commercial loop antenna to use as a reference
      antenna.

73 Kees K5BCQ

Re: Nextion 5/Enhanced for KD8CEC 1.2?

Joe Puma
 

Mark I am catching up with your progress and it looks like you are doing great. I haven’t make any updates on my end.  

Not sure if you had a look at the bandscope but the sliders range don’t match with the visible bandwidth. You are much better at this then I so I appreciate your work so far. I will redo the graphics for the dsp page and I think that’s about it. 

Joe
Kd2nfc 



On May 30, 2019, at 10:02 AM, Mark Hatch <mark2382@...> wrote:

Note for future.... Perhaps the new nano would make a difference...

Unfortunately, even though we have a higher resolution screen, cannot get any more data out of the I2Cmeter. Tried doubling FFT and Samplesize and ran out of memory. So larger screens are stuck with same amount of data, no finer resolution possible (unless I make room by disabling the morse code translator) and so the display of the spectrum will be blocky.  

Wonder if it would be possible to add yet another nano and split the decode and spectrum information? KD8CEC any thoughts?

73
Mark
AJ6CU

Re: Antuino

Michael Aiello
 

I was wondering if your results were particular to your unit, or could be seen generally, so I tried reproducing your experiment, and got very similar results. Using an MFJ antenuator, ran the test on 40 meters, see plot below

73, Mike N2HTT

Re: Nextion 5/Enhanced for KD8CEC 1.2?

Mark Hatch
 

joe,

Here is my latest. Think that the major functional issues are licked. Lots of cosmetics and I really want to address the inconsistency of the UX (.e.g, Home is sometime an icon, sometimes words, sometimes top, sometimes bottom and even middle...

The bandscan is fine, but we have a lot of vertical space that we can use for the scan. That is my next point. Let me know if you see anything, Still very much an amateur here.

I have also put this file under my call sign AJ6CU

73
Mark
AJ6CU

Re: Availability of Mag Loop and other stuff...

Jack, W8TEE
 

You're probably right, but as Allison pointed out, the radiation pattern varies with frequency and, quite honestly, I have little interest in 2M. We will be doing some experiments and readers can choose to digest or ignore what we report.

Jack, W8TEE

On Sunday, June 2, 2019, 1:54:29 PM EDT, iz oos <and2oosiz2@...> wrote:


Maybe it would be easier to test if made for the 2m band and compare with a ground plane and a dipole at different heights.
It is interesting the link https://www.lnrprecision.com/store/W4OP-Loop-Antenna-p69633466 which deals with the efficiency of commercial small loops. If you can really obtain a small loop with a 50% efficiency I would be really interested to know more about it.


Il 02/giu/2019 19:20, "Arv Evans" <arvid.evans@...> ha scritto:
Antenna measurements are for the most part relative to some measured reference signal between
the antenna being tested and the remote reception point.  Antenna at the remote reception point
would seem to be immaterial as long as it does not change characteristics during the tests.  In most
antenna test ranges it is the device being tested that is rotated with the received signal at a fixed
point being measured.  This allows measurement and documentation of signal levels at various
angles of radiation.  Rotating or moving the receiving site is not necessary and would probably
invalidate the measurements. 

Small loop antennas are interesting for another reason.  They can be mounted and measured in
either horizontal or vertical position relative to the local ground plane, or at any angle in between. 
This gives one an idea of which propagation angle might be more advantageous, but only an
idea of that.  Propagation at later dates may totally invalidate any reference measurements that
have been made and published. 

My 2 pence worth. 

Arv
_._


On Sun, Jun 2, 2019 at 9:39 AM ajparent1/KB1GMX <kb1gmx@...> wrote:
Jack,

Not showing off, no one is paying for it.  However when someone claims a loop
that 1-2db below a EFHW (or a dipole) that's pretty close to saying my 10 year
old Tacoma can win at Indy.  In short, not likely or the Indy cars had an unusual
handicap, like no fuel and must be pushed by pit crew.   Reality is that the EFHW
is pointed in some random direction relative to the station and the loop is aimed
though its 3db beam width is likely far wider than the EFHW or a standard dipole
at reasonable height.  That makes its aim very wide where a 80-10 EFHW on
40M will at best have a pattern with a beam width that is narrow as its 1
wavelength long.   I can claim and prove my square loop on 6M at 7ft is better
than my portable 6M full wave length rectaangle loop at 25ft  by pointing the
edge of the loop to the station at distance as the front to side is easily 20db
down.  For that I'm at least the same horizontal polarization.  The square loop
under that condition is about 14db better however if the big loop is aligned its
4 db worse.  In short that proves the big loop does really work and also proves
the omnidiriectional square loop is superior when omnidirectional coverage
is required.

In short comparing it to any antenna without some form of controls and claiming
performance is at best meaningless.    A valid compare is a full size vertical with
elevated radials as it will have known gain and similar takeoff angles.

Loops are cool antennas but they are small antennas and they nominally will be
negative gain compared to any dipole.  Its the nature of antenna compromise.

Fyi: the testing part is to show how difficult it is to get meaningful real world
test data with any accuracy at HF because of distances and even local
surface propagation.   Modeled is of value but care must be taken to use a 
model that works with small loops and real grounds (NEC4.2 engine).

As to helpful.  Yes I want people to realize the limits of small antennas and
the claims sometimes made that are against all modeled data and practical
theory never minding prior works done to verify the models.  To that I see a
lot of suppliers and articles for loops making claims like this is the new
better sliced bread.  

I use loops and I do apply them as they have characteristics that make
them useful.  First being they are self contained antennas. The other
feature is the nulls and their insensitivity to close in electrostatic fields.
Its what they are good at even when they are full sized 1lambda loops.

Allison

Re: Availability of Mag Loop and other stuff...

ajparent1/KB1GMX
 

Radiation pattern of the reference antenna EFHW varies with frequency. 

Loops however are very predictable and the pattern is well understood and
does not change with frequency until it no longer a small loop, its why they
are used.

A multi turn loop has a lower frequency to size (total lenght) where the pure loop
behavior departs from the predicted.  Its easy to see that as the deep nulls are no
longer along the though axis.  By then a smaller loop is likely desirable.

The whole 2M thing was a frequency where testing can be done without great
time and expense.  One does not have to be interested in the higher frequency
to get useful and accurate data.   It is a common practice in the industry to scale
to a frequency where its easy to do the needed testing in smaller spaces or even
a metallic or wood work surface.  

I do have a 144mhz (4 inch diameter) tuned loop for noise DF (RX only or under 1W)
and the nulls allow me to determine where on a pole a noise source is once I know
which pole.  Very sharp nulls.

In general two costly items are the cap and if padding caps are used suitable high
voltage and high current fixed value caps of decent Q.     The element is copper
tube and not a high price item considering how much is required.  Copper is
preferred over aluminum as aluminum has a higher resistance and if oxidized
(its normal state) the oxide surface s a near insulator.  Also copper can be hard
soldered (silver alloy) using MAPP gas torch.   

Allison

Re: Pin Change Interrupt library

Dexter N Muir
 

Thanks for that! Installation of the IDE years ago created a 'libraries' directory, so I git cloned there by Terminal (RasPi).

Now to find a mini- (not micro-) USB cable. Had one once: wonder where it waltzed off to? :)

Ah. Found. On a portable hard-drive.
OK, verify. Still no go.

Sketch/Import Library, it shows as Contributed but still no go: won't find the library. Where does that have to be put? That's what I mean by 'instructions' - or link to ...
Jeeez ... Am I *THAT* dumb?


Re: HFSignals poor business practices

Ken Hansen
 

Take care, thank you for being part of this community.

Ken, N2VIP

On Jun 2, 2019, at 1:01 PM, John Cardoso <ve9pct@...> wrote:

This will be my last post on this subject. Cheers to all.