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Re: Why not a resonant loop?
开云体育Hi Bob, I like messing with tuned loops as well. It was with Bertha (my first multi-turn tuned loop) that I was able to hear my first LWBC transmissions after several years of trying with numerous full sized V's and verticals.One thing that you mentioned that sparked my attention was your use of a dsp noise canceller. My only experience with them has been the canned NR on box rigs like the FT-1000, etc. I never did find any settings that I thought I could tolerate longer than a few minutes and I never really thought they did much good other than make the audio sould like it coming from outer space. Do you by chance have a short video demonstrating the effectiveness of your NR in action?? If not even a 2-3 minute cell phone video uploaded to YT or to Google drive, dropbox etc. Would love to see an effective noise canceller/reducer in action esp during distant lightning strikes at night.? 73 Gedas, W8BYA EN70JT Light travels faster than sound..... This is why some people appear bright until you hear them speak. On 1/25/2025 1:58 PM, Bob, N1KPR via
groups.io wrote:
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Re: Why not a resonant loop?
With receive antennas, Signal To Noise is the important factor, and not absolute signal strength.
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However, it's very easy to be fooled into thinking that a weaker signal has a subjectively better Signal to Noise Ratio than a stronger signal, because the background noise drops below our hearing "threshold", or may be masked by "smoother" sounding internal noise from the receiver itself.
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It's a psychoacoustic phenomenon, which can be emulated by increasing attenuation ahead of a receiver.
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In an urban environment, it's most likely that the local noise floor will be the limiting factor, and you won't notice any difference between a narrowband passive tuned loop, or a similar sized broadband active loop. It's only when you get out into the countryside, with a very low noise floor, that you may observe some differences, but even then a decent broadband active loop will most likely be adequate.
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Regards,
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Martin
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On Sat, Jan 25, 2025 at 06:58 PM, Bob, N1KPR wrote:
My point is that the tuned loop is about 18dB below the 160 wire and about 22-24dB below the vertical 80, but with significantly less noise |
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Re: Why not a resonant loop?
After many hours of experimentation I settled on a tuned loop for the family room entertainment feed; news, traffic and weather. I'm using an old W-J 8711 demo/loaner unit that's quite beat up, but works as expected. As I mentioned in an earlier post, I have recorded signal strengths from either an 80-meter vertical or the 160-meter wire at 35 feet. So I can gauge from the known antennas and the known AM b'casters as to what levels I should need to get. The tuned loop is about 35 feet from the house and was on a cheap rotator (now broken) and feeding a bias-tee to a variactor (BB112). With the 330uH loop and the diode tuning I can cover 500kHz thru 2MHz. I generally have the loop toward NYC which is directly SW from here. To reorient the loop I use an "Armstrong rotator." That means I need to go outside and turn it myself. East for New Haven and RI, NNE for Hartford/Boston and the SW for NYC The tuned loop feeds me a much better diet that the Mobius or other homebrew loops. As was mentioned, the tuned loop is limited as to what the diode can cover to resonate the 330uH loop. In the evening, I switch to the Pixel Pro for International stuff, also on a cheap rotator (this one still works). My point is that the tuned loop is about 18dB below the 160 wire and about 22-24dB below the vertical 80, but with significantly less noise. With a preamp (LNA) I can boost the loops up to the Ham antenna's strength. But, that gets to be a feel-good situation, since the QRN/QRM is also amplified. Added note: A good DSP Noise Reduction device (I use BHI) can make life a lot more enjoyable, especially for long-term listening. gud sigs to all, 73, Bob, N1KPR
Engineering, where enigma meets paradox
On Saturday, January 25, 2025 at 01:24:59 PM EST, Nick Hall-Patch <nhp@...> wrote:
In the past, many of us heard great MW DX with a tuned loop next to the receiver.? However, such a loop now would be likely to hear only local electrical noise from house wiring, wouldn't it?? That's pretty much all that mine can hear now.
If one has some property, it may be possible to put a tuned loop away from the house, but protected from the weather, and tuned with a varicap diode, which itself may affect loop Q.? But, then one loses the ability to turn the loop to null interfering stations on the chosen channel, which was another advantage of the indoor tuned loop. Others have mentioned the necessity of a wide band loop for SDR recordings, but if one can live with a single tuned channel, is there any advantage to a tuned over an untuned loop?? That is, can something be heard on one but not the other?? ?I did try a remotely tuned Kiwa loop vs. a Flag antenna on trans-Arctic signals here, and didn't find any advantage, but the testing was not exhaustive.? ?Something more to add to the list, I guess. best wishes, Nick ? On Sat, 25 Jan 2025 08:17:14 -0800, "JohnT via groups.io" <jtstein46@...> wrote: ? Greetings.? I am a frequent "lurker" and very infrequent "poster" to this forum, my interest is primarily MW.? I usually use a 1m diameter resonant loop and am puzzled as to why resonant loops seem to be out of favor with most of the group members.? The resonant peak provides both "free", noiseless gain to the signal of interest while also rejecting signals at frequencies other than resonance, eliminating the need for high second- and third-order intercept performance.? Granted the broadband loops that are much discussed on the forum can acquire broad swaths of the RF spectrum essentially simultaneously, is this a significant advantage given the fact that the frequency of the signal of interest is known?
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Would someone please discuss the advantages of the broadband loop over a resonant one, have I missed something??
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Thanks
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JohnT
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Re: Why not a resonant loop?
In the past, many of us heard great MW DX with a tuned loop next to the receiver.? However, such a loop now would be likely to hear only local electrical noise from house wiring, wouldn't it?? That's pretty much all that mine can hear now.
If one has some property, it may be possible to put a tuned loop away from the house, but protected from the weather, and tuned with a varicap diode, which itself may affect loop Q.? But, then one loses the ability to turn the loop to null interfering stations on the chosen channel, which was another advantage of the indoor tuned loop. Others have mentioned the necessity of a wide band loop for SDR recordings, but if one can live with a single tuned channel, is there any advantage to a tuned over an untuned loop?? That is, can something be heard on one but not the other?? ?I did try a remotely tuned Kiwa loop vs. a Flag antenna on trans-Arctic signals here, and didn't find any advantage, but the testing was not exhaustive.? ?Something more to add to the list, I guess. best wishes, Nick ? On Sat, 25 Jan 2025 08:17:14 -0800, "JohnT via groups.io" <jtstein46@...> wrote: ? Greetings.? I am a frequent "lurker" and very infrequent "poster" to this forum, my interest is primarily MW.? I usually use a 1m diameter resonant loop and am puzzled as to why resonant loops seem to be out of favor with most of the group members.? The resonant peak provides both "free", noiseless gain to the signal of interest while also rejecting signals at frequencies other than resonance, eliminating the need for high second- and third-order intercept performance.? Granted the broadband loops that are much discussed on the forum can acquire broad swaths of the RF spectrum essentially simultaneously, is this a significant advantage given the fact that the frequency of the signal of interest is known?
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Would someone please discuss the advantages of the broadband loop over a resonant one, have I missed something??
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Thanks
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JohnT
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Re: Why not a resonant loop?
Yes, the frequencies of our targets may be known.? For loops my interests range from the Schumann Resonance around 7 Hz plus harmonics to roughly 2 to 4 MHz.? Tuned loops have an extremely high-Q.? For example, while using my 1-meter diameter tuned loop for transmit on 40-meters (7 MHz), my 2:1 SWR bandwidth is only some 6 to 8 kHz wide.? Beyond that on receive, I can easily detect its rapid response falloff. ?? Most of us are not after a single frequency as mentioned with the NDB band.? Even with AM BCB "DX'ing", a tuned loop would yield single-station tuning.? The loop would have to be re-resonated every 10 kHz (the AM BCB frequency spacing in the US).?? Dave - W?LEV? On Sat, Jan 25, 2025 at 4:17?PM JohnT via <jtstein46=[email protected]> wrote:
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Dave - W?LEV |
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Re: Why not a resonant loop?
On Sat, Jan 25, 2025 at 08:17 AM, JohnT wrote:
I usually use a 1m diameter resonant loop and am puzzled as to why resonant loops seem to be out of favor with most of the group members.? ? Is this a multi turn 1M resonate loop? Do you have a tuning capacitor? What is the frequency range of your loop?
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???????????????????????????????????????????????????????? Mikek |
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Re: Why not a resonant loop?
开云体育
I make overnight recordings of the NDB band, 200-530KHz. I need a broadband response to do that.
Tony
AD0VC
From: [email protected] <[email protected]> on behalf of JohnT via groups.io <jtstein46@...>
Sent: Saturday, January 25, 2025 9:17 AM To: [email protected] <[email protected]> Subject: [loopantennas] Why not a resonant loop? ?
Greetings.? I am a frequent "lurker" and very infrequent "poster" to this forum, my interest is primarily MW.? I usually use a 1m diameter resonant loop and am puzzled as to why resonant loops seem to be out of favor with most of the group members.? The
resonant peak provides both "free", noiseless gain to the signal of interest while also rejecting signals at frequencies other than resonance, eliminating the need for high second- and third-order intercept performance.? Granted the broadband loops that are
much discussed on the forum can acquire broad swaths of the RF spectrum essentially simultaneously, is this a significant advantage given the fact that the frequency of the signal of interest is known?
?
Would someone please discuss the advantages of the broadband loop over a resonant one, have I missed something??
?
Thanks
?
JohnT
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Why not a resonant loop?
Greetings.? I am a frequent "lurker" and very infrequent "poster" to this forum, my interest is primarily MW.? I usually use a 1m diameter resonant loop and am puzzled as to why resonant loops seem to be out of favor with most of the group members.? The resonant peak provides both "free", noiseless gain to the signal of interest while also rejecting signals at frequencies other than resonance, eliminating the need for high second- and third-order intercept performance.? Granted the broadband loops that are much discussed on the forum can acquire broad swaths of the RF spectrum essentially simultaneously, is this a significant advantage given the fact that the frequency of the signal of interest is known?
?
Would someone please discuss the advantages of the broadband loop over a resonant one, have I missed something??
?
Thanks
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JohnT |
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Re: Steve ugly-build LZ1AQ using MPS2222 sweeps uploaded to Photos
On Sat, Jan 25, 2025 at 07:48 AM, Chris Trask - N7ZWY/WDX3HLB wrote:
Even though I'm always interested in monolithic transistor arrays, the overall lack of data in that datasheet makes me skeptical about using them.? I'll stick with the CA/MC/LM3046 for now.??? Chris, knowing your history, I would think you would be the one to put this in a circuit and analyze it, and let the world know if it is useful in the RF receiving world. Most of us don't know how to test for good, better, and best. ? ? ? ? ? ?? ????????????????? Mikek |
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Re: Steve ugly-build LZ1AQ using MPS2222 sweeps uploaded to Photos
Even though I'm always interested in monolithic transistor arrays, the overall lack of data in that datasheet makes me skeptical about using them.? I'll stick with the CA/MC/LM3046 for now. ? Chris ? When the going gets weird, the weird turn pro - Hunter S. Thompson -----Original Message-----
From: <[email protected]> Sent: Jan 24, 2025 4:31 AM To: [email protected] <[email protected]> Subject: Re: [loopantennas] Steve ugly-build LZ1AQ using MPS2222 sweeps uploaded to Photos ? ?
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On Friday, January 24, 2025 at 06:28:02 a.m. EST, Paul V Birke via groups.io <nonlinear@...> wrote:
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Always wondered what about R1 and R2 being replaced by separate current sources?
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Simple FET ones or Full Wilson with matching transistors (THAT Corp sells chip with 4 matched HF transistors)
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Would be worth a try even if just running a model to see any serious positive effect.
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best Paul
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On Thursday, January 23, 2025 at 11:41:47 p.m. EST, vbifyz via groups.io <3ym3ym@...> wrote:
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On Thu, Jan 23, 2025 at 07:11 PM, <biastee@...> wrote:
Imbalance between top and bottom sections affects IP2 (which I don't see in the measurements), and not so much IP3.
Otherwise, very good and thorough work.
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73, Mike AF7KR
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Re: Experimenting with Loop Antennas
On Fri, Jan 24, 2025 at 07:42 PM, Alberto di Bene wrote:
mc? ?--> means nothing... only mc/s, i.e. megacycles per second is a measure of frequency Megacycles per second was a measure in the past. To be precise, until 1960. With the organization of the International System of Units (SI), the cycle per second was officially replaced by the "hertz" (Hz) or "s?1".
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Regards
Fred |
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Re: Experimenting with Loop Antennas
On Fri, Jan 24, 2025 at 07:42 PM, Alberto di Bene wrote:
Well said. Capitalization (not to mention punctuation) is going down the drain in this age of phone texting.
That said...
SI missed its chance to dump "k" for "K", so that capitalization is consistent throughout negative and positive multipliers.
KKelvin shouldn't be a problem.
Sort-of similarly, deprecated Hecto (H) and Deka (D) could coexist with electromagnetism (and Hz).
What an imperfect world :-).
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Re: Steve ugly-build LZ1AQ using MPS2222 sweeps uploaded to Photos
Hi Dave,
Are you referring to the balun inside the dummy aerial? If yes, I have initially constructed the dummy aerial as in the top circuit (balun in between single-ended L-network & preamp) in the linked image below:
The above arrangement conveniently allowed the use of a single-ended L-network, but had a couple of issues: 1. the balun altered the L-network output impedance, and 2. momentary un-levelling of the test source during frequency sweep.
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Consequently, to overcome the aforementioned problems, the dummy aerial was subsequently changed to the bottom circuit which I had initially resisted because it requires a balanced L-network.
73, Leong, 9M2LCL, ex-9W2LC.
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Re: Experimenting with Loop Antennas
开云体育Fun discussion.
I once found a?31.6875nHz signal in a 50-year barometric pressure record of midnight samples. The rest was 1/f noise.
Andrew VK5CV
From: [email protected] <[email protected]> on behalf of Phil via groups.io <k0twa@...>
Sent: Saturday, January 25, 2025 8:20:38 AM To: [email protected] <[email protected]> Subject: Re: [loopantennas] Experimenting with Loop Antennas ?
44.7 microHertz = [approx.] 6.7067664^12 meters
THAT'S a REALLY long wavelength.
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Phil, K0TWA
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Re: Experimenting with Loop Antennas
So, not only geologists use units of measure below 1 Hz....Even as a radio hobbyist, I was looking for mHz signals in the 90's. I imagine many more were, for many more decades before me. Here's something to think about, I like to toss it out there every now and then, to see who responds, and how: "DC", isn't. Kurt |
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Re: Experimenting with Loop Antennas
Physicist here... beware.
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mHz --> means millihertz,? ?10^-3 Hz
MHz --> means megahertz, 10^6 Hz?
mc? ?--> means nothing... only mc/s, i.e. megacycles per second is a measure of frequency
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:-)
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73? Alberto? I2PHD
P.S. My new software Argo V2, soon to be release, has a selectable resolution in frequency that can range down to 44.7 uHz. i.e. 44.7 millionths of a Hz...
So, not only geologists use units of measure below 1 Hz.... |
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Re: Steve ugly-build LZ1AQ using MPS2222 sweeps uploaded to Photos
If the L-network is single ended - common mode for coax - the balun belongs BEFORE the network!?? The balun converts differential mode to common mode.? That's why it is termed a "balun:? Balanced (to) Unbalanced. Dave - W?LEV On Fri, Jan 24, 2025 at 2:11?AM biastee via <biastee=[email protected]> wrote:
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Dave - W?LEV |
Bob, N1KPR
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