Interesting upgrade for a Youloop
I ordered an SMA switch from this company today and also found this Youloop upgrade. Anyone tried this?
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Zack N8FNR?
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Interesting upgrade for a Youloop
I ordered a four port SMA switch from this company today and also found the upgrade for a Youloop. Anyone tried this?
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Zack N8FNR
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Re: LZ1AQ using BFU590QX transistors
Mike,
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With the inputs shorted they both were 105dBm at 1MHz.
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Everett
In a message dated 10/29/2024 10:01:59 AM Central Daylight Time, 3ym3ym@... writes:
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Hi Everett,
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Can you compare the noise level of the 2 variants with the input shorted? Not a true noise figure measurement, but a relative comparison.
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73, Mike AF7KR
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Re: LZ1AQ using BFU590QX transistors
Sorry about that, yes it is 13.8VDC
In a message dated 10/29/2024 10:04:09 AM Central Daylight Time, groups@... writes:
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Do you mean 13.8VDC? I think there is a typo.
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Mike M
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Re: LZ1AQ using BFU590QX transistors
Everett,
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Do you mean 13.8VDC? I think there is a typo.
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Mike M
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Re: LZ1AQ using BFU590QX transistors
Hi Everett,
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Can you compare the noise level of the 2 variants with the input shorted? Not a true noise figure measurement, but a relative comparison.
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73, Mike AF7KR
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LZ1AQ using BFU590QX transistors
I just finished building 5 LZ1AQ loop amplifier boards, 4 of which I used? 2SC5551 transistors. The 5th one I used BFU590QX transistors.
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Running sweeps on the 2 looking at both impedance and gain, one with 2SC5551s and the other using BFU590QX, I saw very little difference between the two. Both boards were supplied 3.8VDC, the 2SC5551 board ran at 142mA, the BFU590QX board ran at 130mA.
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I checked both boards with my SA and saw no signs of oscillation on either board.
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Everett N4CY
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Fred,
Thanks¡ I will have to put my engineering hat back on, I will give them a read. ?
I was hoping that it was simple as better broad band gain, greater null rejection, greater noise reduction etc¡
Thank you again, after I read through it I come back if I have questions.
Thanks?
Tom
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Tom Anderson
SDR_Radio@...
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On Oct 27, 2024, at 3:27?AM, Fred M <dl4zao@...> wrote:
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On Sat, Oct 26, 2024 at 07:54 PM, Tom ANderson wrote:
what is the advantage of a dual loop over a single loop. ?Also what would be the result if the dual loops where in parallel vice on top of each other
It depends how the loops will be connected togehter. Your are increasing the active area of the loop which is penetrated by the magnetic field.
Please read here:
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and here:
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regards
Fred
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The advantage of this, is that by projecting the plotted curves, down from the point at which they intersect, you can see what levels of signals are likely to produce unwanted IMD that is above the system noise floor.
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Note that IP2 increases at twice the rate of the actual signal level, and IP3 increases at three times the rate.
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For example, if an amplifier produced values such as:-
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IOP2 of +55dBm and IOP3 of +15dBm
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Both would generate an IMD level of around -100dBm (well above a typical receiver noise floor) for a signal level of around -25dBm.
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But at a lower signal level of around -30 to -40dBm, which is typical of many actual antennas systems, the IMD is below the receiver noise floor at around -130dBm.
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Generally speaking, the higher the IP values, the less likely you are to hear spuriously generated signals and noise, which will degrade the overall noise floor of your receive system.
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However, actual systems have many signals present at the same time, so systems require additional margin to deal with this. Two tone testing is only an indicator of performance, but it has the advantage of being a repeatable, and standardised bench test.
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Regards,
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Martin
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On Sun, Oct 27, 2024 at 01:33 AM, Andy wrote:
OIP2 and OIP3 are not the levels of signals you would ever actually use.? They are found by extrapolating the curves (first- and second-order distortion levels) until they intersect, putting them well above the actual (test or otherwise) signal levels.? Often one can never reach those levels at all.? They are points on the extrapolated lines.
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Ah, OK, I was referring to the inductors used in the Bias Tee, and equivalent in the amplifier. I had not spotted the other L2 (1uH) in the amplifier circuit.
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The Bias Tee has a 470uH in the DC feed, the amplifier has 100uH, and both of these are connected in parallel across the RF signal path.
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IMHO it would be preferable to standardise all of these inductors, to be the same value, for improved LF performance and commonality of parts.
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Regards,
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Martin
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On Sat, Oct 26, 2024 at 09:42 PM, Andy wrote:
It's a big difference between 470 uH and 1 uH (not 1 mH!).? One blocks in-band RF, the other passes it as a tuning element.
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On Sat, Oct 26, 2024 at 07:54 PM, Tom ANderson wrote:
what is the advantage of a dual loop over a single loop. ?Also what would be the result if the dual loops where in parallel vice on top of each other
It depends how the loops will be connected together. Your are either increasing the active area of the loop that is penetrated by the magnetic field or you are reducing the loop's inductivity L. The relation Area/Inductivity (A/L) is a figure of merit for a small magnetic loop antenna.
Please read here:
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and here:
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regards
Fred
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Everett
Sorry for a basic question.
what is the advantage of a dual loop over a single loop. ?Also what would be the result if the dual loops where in parallel vice on top of each other?
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Thanks
Tom
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On Sat, Oct 26, 2024 at 08:08 PM, James Redding WA9VEZ wrote:
Perhaps the +98.4 dbm OIP2 on the PDF needs a typo corrected.
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OIP2 and OIP3 are not the levels of signals you would ever actually use.? They are found by extrapolating the curves (first- and second-order distortion levels) until they intersect, putting them well above the actual (test or otherwise) signal levels.? Often one can never reach those levels at all.? They are points on the extrapolated lines.
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That would be an incredibly bad figure for OIP2, making it unusable.
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Andy
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Hi Everett,
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Perhaps the +98.4 dbm OIP2 on the PDF needs a typo corrected. Perhaps -98.4 dbm ? Would also be nice to know the F2 for the intermod.
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Largest RF I ever worked with was only +85 dbm and was water cooled. Exciting lessons with arcing plate choke resonances!
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jim/vez
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On Sat, Oct 26, 2024 at 04:38 PM, Martin - Southwest UK wrote:
Why not standardise on a 470uH or 1mH value for all three inductors L1, L1 & L2 ?
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It's a big difference between 470 uH and 1 uH (not 1 mH!).? One blocks in-band RF, the other passes it as a tuning element.
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Andy
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Hi Everett,
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Looks nice, some other suggestions.
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Why not standardise on a 470uH or 1mH value for all three inductors L1, L1 & L2 ?
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I'd also put the LED after the Polyfuse, so that you can see if it has tripped.
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Regards,
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Martin
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Andy,
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That is a mistake on the schematic, thanks for spotting that, I will have to correct that. It correct on the boards.
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Everett
In a message dated 10/26/2024 11:55:24 AM Central Daylight Time, ai.egrps@... writes:
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How come the input protection diodes D4 and D5 both have their cathodes to the input pin and anodes to ground - whereas D2 and D3 on the other input lead are connected in opposing polarity to one another?
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Andy
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Everett,
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How come the input protection diodes D4 and D5 both have their cathodes to the input pin and anodes to ground - whereas D2 and D3 on the other input lead are connected in opposing polarity to one another?
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Andy
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I have attached a link that gives info on my newest design of the improved LZ1AQ loop amp. It is being offered in several different configuration, including ideas for the experimenter that want a receive loop antenna.
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Everett N4CY
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https://drive.google.com/file/d/1iSsCVMf3OHZnzMIGeOVt3Q-_P-8oBD33/view?usp=sharing
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Everett N4CY
Clint Chron
James Redding WA9VEZ