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Hi all,
This is not about whether to buy genuine, knock-off or home construction, I'm just experimenting but I am unsure of the results.
Sorry it’s a longish post.
I have made a Mobius loop from some RG213 coax I had laying around from years ago, the diameter of the loop is about 76cm and fixed to a short piece of wood to hold it.
The feedline is about 5m of RG58 terminated in a PL259.
I am not currently interested in VHF and up, and although my interest is in HF, the lower HF, MF and LF are what I am trying to improve with the homemade Youloop.
The confusing point for me now is the transformer and what affect its windings or core composition have on the performance of the loop.
The reason here is that I have ordered (twice) some BN-73-302 cores for Aliexpress (I know, but at a few £ delivered its worth a chance, especially as I got a full refund for both 'fake' sets).
I eventually ordered from a reputable UK company, but they are BN-73-202's which makes them a few mm longer and I also had a few BN-43-202's lying around.
I wound several transformers with 1:1, 4 turns each side, which is where I found out that the Aliexpress ones were fake, I initially thought they were type 43, but I was getting strange inductance readings of around 15 to 17uH, yet the 43's were around 35uH, so I have no idea what the Aliexpress ones were!
In my loop, I made a socket to hold the transformers and fitted the transformers to a plug affair, this way I could 'hot swap' the transformers for comparison.
After messing about a bit, I ended up with 3 transformers, all 1:1 ratio:
Type 43, 4 turns, 35uH
Type 73, 4 turns, 200uH
Type 73, 5 turns, 300uH
(These are approximate inductance values as my meter is not so accurate, but they seem to be in the correct region).
Here is the puzzle.
Using the Airspy HF+ Discovery and my laptop, In the middle of no-where at the side of the road, I tested reception on various frequencies from as low as 18khz up to about 7Mhz, changing the transformer for each frequency.
The results were good, but the thing concerning me is that there was NO detectable difference between the 3 different transformers both in signal strength and noise level.
So, I have a few questions to the people in the know!
Is there (should there be any) significant difference in the following:
1. Type of coax?
2. Type of transformer core material ?
3. Number of turns of the transformer (noting always 1:1 in this case)?
Should I have expected a difference in reception between the transformers?
Thanks
Martin
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On Sun, Dec 22, 2024 at 03:06 PM, Martin wrote:
Is there (should there be any) significant difference in the following:
1. Type of coax?
Yes. The capacitance of the coax is important.
2. Type of transformer core material ?
Yes. It defines the resonance lobe and the optimal number of turns.
3. Number of turns of the transformer (noting always 1:1 in this case)?
The number of turns defines both the resonance and impedance.
Should I have expected a difference in reception between the transformers?
It depends. If your parameters are way off, you will not see any significant change. The recommendation is to get the official design working, then start from there.
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Thanks Prog,
So I think the first change to make is to use different coax for the loop then.
As for the transformer core material, what is different is the inductance and therefore I understand this affects the resonance of the loop, and as you pointed out about the capacitance of the coax, then even with the correct core material and turns, the resonance would be different to the official design.
I was still impressed by its reception capabilities though, even as it is, but if I use the correct coax, then hopefully it will improve even more.
Please understand, these are only my own experiments out of curiosity and I am in no way trying to save the cost of a genuine Youloop, but I wouldn't want to buy a genuine one and then hack it up to play.
Thanks Martin
On Sun, Dec 22, 2024 at 03:06 PM, Martin wrote:
Is there (should there be any) significant difference in the following:
1. Type of coax?
Yes. The capacitance of the coax is important.
2. Type of transformer core material ?
Yes. It defines the resonance lobe and the optimal number of turns.
3. Number of turns of the transformer (noting always 1:1 in this case)?
The number of turns defines both the resonance and impedance.
Should I have expected a difference in reception between the transformers?
It depends. If your parameters are way off, you will not see any significant change. The recommendation is to get the official design working, then start from there.
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If the highest band of interest is 40m, you can target a peak around 4 MHz. Try different number of turns keeping a 1:1 ratio until you get the highest level of signal (including noise) around 4 MHz. Keep the coax and the ferrite. Once you get that peak, optimize the other parameters.
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Out of this thread: where Can i buy e genuine YouLoop? Wimo charge offensive fares for transport and a surcharge for credit card; ITEAD, from who I bought all my three Airspy, don’t list YouLoop; on Aliexpress there are a lot I believe non original. Now I am using a Aliexpress unit I bought a couple of year ago, but I am curious about the original. Thank you Roberto Il giorno 22 dic 2024, alle ore 18:36, prog <info@...> ha scritto:
If the highest band of interest is 40m, you can target a peak around 4 MHz. Try different number of turns keeping a 1:1 ratio until you get the highest level of signal (including noise) around 4 MHz. Keep the coax and the ferrite. Once you get that peak, optimize the other parameters.
===== SDR## 1921 Windows 11 running in Parallels Desktop MacBook pro M1Max Airspy+ HF Discovery (on line) Airspy R2 (on line) Airspy Mini (on line) Spyserver: rob-casa-ge (dot) ddns (dot) info:5555 Airspy+ HF Discovery rob-casa-ge (dot) ddns (dot) info:5556 Airspy Mini QTH Genova Italy nbrc.mynetgear (dot) com:5555 Airspy R2 QTH Breuil Cervinia (Aosta Valley) Italy
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On Sun, Dec 22, 2024 at 07:10 PM, Roberto Cipriani wrote:
where Can i buy e genuine YouLoop?
One easy way to check what NOT to buy is from their pictures.
Crap versions have stupid little labels and light blue coax.
And they are 3 dB or worse on SNR.
I wish Airspy would pull out of China. Of course I'd pay a bit more.
--
Paul White (Grumpy Old Git)
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At that frequency probably not. A level change would come from a
change in turns ratio.
{^_^}
On 20241222 05:26:43, Martin via
groups.io wrote:
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Показати цитований текст
Hi
all,
This is not about whether to buy genuine, knock-off or home
construction, I'm just experimenting but I am unsure of the
results.
Sorry it’s a longish post.
I have made a Mobius loop from some RG213 coax I had laying
around from years ago, the diameter of the loop is about 76cm
and fixed to a short piece of wood to hold it.
The
feedline is about 5m of RG58 terminated in a PL259.
I
am not currently interested in VHF and up, and although my
interest is in HF, the lower HF, MF and LF are what I am
trying to improve with the homemade Youloop.
The
confusing point for me now is the transformer and what affect
its windings or core composition have on the performance of
the loop.
The
reason here is that I have ordered (twice) some BN-73-302
cores for Aliexpress (I know, but at a few £ delivered its
worth a chance, especially as I got a full refund for both
'fake' sets).
I
eventually ordered from a reputable UK company, but they are
BN-73-202's which makes them a few mm longer and I also had a
few BN-43-202's lying around.
I wound several transformers with 1:1, 4 turns each side,
which is where I found out that the Aliexpress ones were fake,
I initially thought they were type 43, but I was getting
strange inductance readings of around 15 to 17uH, yet the 43's
were around 35uH, so I have no idea what the Aliexpress ones
were!
In
my loop, I made a socket to hold the transformers and fitted
the transformers to a plug affair, this way I could 'hot swap'
the transformers for comparison.
After
messing about a bit, I ended up with 3 transformers, all 1:1
ratio:
Type
43, 4 turns, 35uH
Type
73, 4 turns, 200uH
Type
73, 5 turns, 300uH
(These
are approximate inductance values as my meter is not so
accurate, but they seem to be in the correct region).
Here
is the puzzle.
Using
the Airspy HF+ Discovery and my laptop, In the middle of
no-where at the side of the road, I tested reception on
various frequencies from as low as 18khz up to about 7Mhz,
changing the transformer for each frequency.
The
results were good, but the thing concerning me is that there
was NO detectable difference between the 3 different
transformers both in signal strength and noise level.
So,
I have a few questions to the people in the know!
Is
there (should there be any) significant difference in the
following:
1.
Type of coax?
2.
Type of transformer core material ?
3.
Number of turns of the transformer (noting always 1:1 in this
case)?
Should
I have expected a difference in reception between the
transformers?
Thanks
Martin
|
Hi David,
Confused at your response, are Moonrakeronline giving them away for me to take apart and experiment with? Or will Moonrakeronline answer the questions I posed?
Your comment seems to be from "
> Out of this thread: where Can i buy e genuine YouLoop?" In which case I don't know why you posted this on this thread, as I know exactly where to buy them, which has nothing to do with my post!
Or did you just not read my post correctly?
Apart from that, how are you? You are a blast from the past but you probably don't remember me as it's been many years, that is if you are the David Taylor from Scotalnd who wrote all the weather satellite software!
Hope you're well!
Martin
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On 23/12/2024 14:22, Martin via groups.io wrote: Hi David,
Confused at your response, are Moonrakeronline giving them away for me to take
apart and experiment with? Or will Moonrakeronline answer the questions I posed?
Your comment seems to be from " > Out of this thread: where Can i buy e genuine
YouLoop?"
In which case I don't know why you posted this on this thread, as I know exactly
where to buy them, which has nothing to do with my post!
Or did you just not read my post correctly?
Apart from that, how are you? You are a blast from the past but you probably
don't remember me as it's been many years, that is if you are the David Taylor
from Scotalnd who wrote all the weather satellite software!
Hope you're well!
Martin Martin, I was responding to Roberto Cipriani's question: "Out of this thread: where Can i buy e genuine YouLoop?", where prices and delivery charges were mentioned. Message: https://groups.io/g/airspy/message/50496 in this thread. Yes, you have me and my software nailed down! It's still in use even at EUMETSAT in Darmstadt. Visitors to the control room often comment! I've not done software for the latest satellite generation as there is excellent polar orbiting support in SatDump, and for geostationary in Python with Roman Zamiesal's software. Cheers, David -- SatSignal Software - Quality software for you Web: https://www.satsignal.euEmail: davidtaylor@... BlueSky: @gm8arv.bsky.social, Twitter: @gm8arv
|
I do apologise David, I hadn’t seen the response from Roberto
in the thread!
I still have my SatTV card, Eumetsat encryption key dongle and MSG software.
Not used them in years!
A chat for another topic though!
Thanks
Martin
On 23/12/2024 14:22, Martin via groups.io wrote:
> Hi David,
>
> Confused at your response, are Moonrakeronline giving them away for me to take
> apart and experiment with? Or will Moonrakeronline answer the questions I posed?
>
> Your comment seems to be from " > Out of this thread: where Can i buy e genuine
> YouLoop?"
> In which case I don't know why you posted this on this thread, as I know exactly
> where to buy them, which has nothing to do with my post!
>
> Or did you just not read my post correctly?
>
> Apart from that, how are you? You are a blast from the past but you probably
> don't remember me as it's been many years, that is if you are the David Taylor
> from Scotalnd who wrote all the weather satellite software!
>
> Hope you're well!
>
> Martin
Martin,
I was responding to Roberto Cipriani's question: "Out of this thread: where Can
i buy e genuine YouLoop?", where prices and delivery charges were mentioned.
Message: https://groups.io/g/airspy/message/50496 in this thread.
Yes, you have me and my software nailed down! It's still in use even at
EUMETSAT in Darmstadt. Visitors to the control room often comment! I've not
done software for the latest satellite generation as there is excellent polar
orbiting support in SatDump, and for geostationary in Python with Roman
Zamiesal's software.
Cheers,
David
--
SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: davidtaylor@...
BlueSky: @gm8arv.bsky.social, Twitter: @gm8arv
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Thank you to all who answered my question. Roberto Il giorno 24 dic 2024, alle ore 09:43, Rafal SQ9CWN via groups.io <lemielek@...> ha scritto:
You can buy original YouLoop from RTL-SDR Blog store: https://www.aliexpress.com/item/4001014943156.html
--
Rafal SQ9CWN
===== SDR## 1921 Windows 11 running in Parallels Desktop MacBook pro M1Max Airspy+ HF Discovery (on line) Airspy R2 (on line) Airspy Mini (on line) Spyserver: rob-casa-ge (dot) ddns (dot) info:5555 Airspy+ HF Discovery rob-casa-ge (dot) ddns (dot) info:5556 Airspy Mini QTH Genova Italy nbrc.mynetgear (dot) com:5555 Airspy R2 QTH Breuil Cervinia (Aosta Valley) Italy
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👍
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Il giorno 24 dic 2024, alle ore 17:34, DXer via groups.io <hfdxmonitor@...> ha scritto:
On Tue, Dec 24, 2024 at 10:13 AM, Roberto Cipriani wrote:
Thank you to all who answered my question. Check the price on the RTL-SDR Blog store as well. They are different sometimes.
Vince, VA3VF👍
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Your comment:
"...The confusing point for me now is the transformer and what affect its windings or core composition have on the performance of the loop...."
The Mobius loop was fundamentally designed to detect H field (EM) transients due to nuclear detonations as a transient H field probe. It was optimized for this purpose and not for radio reception although it does function as such, just as any conductor or piece of wire or common unshielded loop.
It fundamentally has a low impedance.
Your transformers are presenting an extremely high impedance mismatch and therefore, poor performance in your use and configuration.
This venue / forum is difficult to provide you with the answers and rationales for you.
Recommend you get a basic peer reviewed university level engineering book on transformers to get basic insight....
Alex
BS Physics / MSEE
30 WPM Extra Class since the 1970's
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On Wed, Dec 25, 2024 at 05:08 PM, Alex P wrote:
Your comment:
"...The confusing point for me now is the transformer and what affect its windings or core composition have on the performance of the loop...."
The Mobius loop was fundamentally designed to detect H field (EM) transients due to nuclear detonations as a transient H field probe. It was optimized for this purpose and not for radio reception although it does function as such, just as any conductor or piece of wire or common unshielded loop.
It fundamentally has a low impedance.
Your transformers are presenting an extremely high impedance mismatch and therefore, poor performance in your use and configuration.
This venue / forum is difficult to provide you with the answers and rationales for you.
Recommend you get a basic peer reviewed university level engineering book on transformers to get basic insight....
Alex
BS Physics / MSEE
30 WPM Extra Class since the 1970's
You will be surprised how the real world parameters differ from the naked abstraction.
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Response to "Prog":
An impedance mismatch is not a 'naked abstraction'....it is a real world practical and measurable reality.
It can be demonstrated as VSWR or Reflected Power....and that includes receiver circuits.
It is a fundamental building block of electrical engineering.
FYI....I've designed operational space satellites and UAV's and launch vehicles and comm systems that work in the real world.
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On Wed, Dec 25, 2024 at 07:02 PM, Alex P wrote:
Response to "Prog":
An impedance mismatch is not a 'naked abstraction'....it is a real world practical and measurable reality.
It can be demonstrated as VSWR or Reflected Power....and that includes receiver circuits.
It is a fundamental building block of electrical engineering.
FYI....I've designed operational space satellites and UAV's and launch vehicles and comm systems that work in the real world.
You can perfectly imagine I'm not that dumb to ignore the mismatch problem altogether. Now the effective strategy to solve it in practice might be counter-intuitive from an academic perspective. Using High-Z Low NF amps is a good example.
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Sure, and Trask addressed this in detail in his design tests as well as HP/Agilent, Analog Devices, TI and Motorola.
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We discussed the research papers of the us airforce about this loop, which were written many years ago, several times.
The mob. loop has three or perhaps four characteristic regimes of Z determined by the arm length each with unique behaviors. The voltage is maximized aka the swr at a 15 degree arm length, and the impedence is closest to 50 ohms as the behavior settles for higher frequencies above 20 degrees.
Now, what i want to know, o illustrious engineer, are two things: first of all, when are we going to see a new design for a wideband loop amp with impedance tracking powered by nanotriode semiconductor junction amplification and cmos dynamic power feedback?
and secondly, when are we going to see a metamaterial patch antenna that utilizes a brewster angle lensing effect created by material boundary domain behavior to create an Rf fresnel lens that offers some rejection of uniform field exciting energy?
yours, a student of the black arts
[Edited Message Follows]
Sure, and Trask addressed this in detail in his design tests as well as HP/Agilent, Analog Devices, TI and Motorola.
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Martin
prog
Roberto Cipriani
David J Taylor