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I had some MPS2222 transistors and built up a quick LZ1AQ and swept it, with the sweeps and picture of the ugly-build added to the Photos. This is only for comparing with Caaarlo's build and sweeps (thanks, Caaarlo, you did a nice job building yours). His nanovna sweep didn't include gain sweep. I used the DG8SAQ VNWA with the same two frequency sweeps, and with calibrated-out 1:1 input transformer (unbalanced to balanced) which shows both input impedance and gain on the same sweep. I used -30 dBm input level to ensure the loop amp is not overloaded. I'm not sure what transformer and turns Caaarlo used; I used a BN73-302 binocular core with 8/8:6 turns which is what I use with a nominal 50 ohm coax cable output. (Same as what Everett Sharp N4CY's LZ1AQ PCB uses.) The transistors run out of gain-bandwidth product at 30 MHz as you can see from the sweep (the gain is rolling off). Caaarlo's loop amp should have similar gain since both used the same transistors. /g/loopantennas/album?id=296351 If that doesn't work, search Photos for "Steve LZ1AQ Sweep".

Everett, I have one of your loop boards and have lost the instructions. I am going to resurrect my broken loop tht I pulle ddown a couple of years ago. I can't find an email address for you so would you please email me at my call @outlook.com TNX and 73 Warren / NI5L

Hi, I am a new member of this group. Callsign HB9VQQ. I have been experimenting with Loop antennas for some time. I have been using a Wlelgood 3.1 loop with a diameter of 1m (single loop) for many years. When I came across the Mag-Loop calculator, I was curious to see if I could improve my RX with a new design. So I came up with a new design with the main focus of reducing inductance and increasing conductor area. I finished building the dual parallel loop yesterday and put it in operation. I am using a Wellgood 4.1 Amp. Wired like this. Should I cross the connections? More Info can be found at /g/wsprbeacon/topic/bigger_wellgood_loop/110398954 So which of the two is better? I use WSPR to compare the decoding performance with my “old” Wellgood loop with 2 RX-888 Mk2 and wsprdaemon. This allows simultaneous WSPR decoding on multiple bands. In my case from 2200 - 40m band (bands of interest). This is my test setup to compare the performance The results can be seen here https://wspr.live/gui/goto/Q4RVJMONR?orgId=1 (still running at the time of this writing). I am not overly happy with the results, especially with the DX Spots (Distance > 3000km) on 40m. I am not sure if my 2 parallel loop design is a good one, maybe 2 crossed parallel loops in the same plane (LZ1AQ) would be better. Also, I am not sure if the Wellgood Amp is well suited for this setup. 73 Roland

A interesting summary on using cat6 for low noise rx antenna feedlines. https://www.youtube.com/watch?v=i44PU8NJf1M I have used a single VE6WZ transimpedance amplifier vertical and I happy with the results especially on the lower frequencies. I dont have RFI noise issues and this antenna performs better as general purpose antenna than the loop especially on NDB targets. It would be practical for small loop antennas especially when you want to protect, power them or bypass the preamp all together. The costs of coax cables seems to be sky rocketing while more commonly used cables like cat6 seems to be falling. Long term it might be in everyone's interesting to design loop amplifiers for feedlines like cat6. I understand that LZ1AQ was the first to use catX cables for a feedline, although twisted pair balanced lines have been around for a while and used on low noise rx antennas in the past. Henry

I made a folder in Photos just now and uploaded the schematics for ALA1530LN, ALA100LN, FLG100LN that I've traced out in the past. There should be complete info there for anyone to be able to make their own. The original leaded 2SK715 jfets are now unobtainable, but there are two SMD equivalents that work just as well, with the 2SK932 preferred since its typical yfs is the same as the 2SK715. One should be able to make one of these for around $50--maybe less. On eBay I see a Chinese seller claims to be selling an ALA1530LN or an ALA100LN for a very high price of around $250, for the loop amp alone! I have no idea if it's a direct clone of the Wellbrook. /g/loopantennas/album?id=296460. The name of the folder is "Wellbrook official traced-out schematics ALA1530LN, ALA100LN, FLG100LN". 73, Steve AA7U On 7/17/2024 2:15 PM, Paul V Birke via groups.io wrote: Dear Martin I thought Steve Ratzlaff did some "unpotting" amongst others Maybe we need to find out what they found. I remember seeing results from at least two "unpottings" best wishes Paul

Not sure if this will be of any help to anyone but a couple of years ago I made up some different CMC and measured their CMR aimed towards VLF-MF use. At the time I was messing around with some of my own modified (larger) youloops etc. Suggest you speed up the video as I tend to babble :-) 73 https://www.youtube.com/watch?v=GhkrQCp15Kc Gedas, W8BYA EN70JT Light travels faster than sound..... This is why some people appear bright until you hear them speak.

Thanks!

I have attached a link the has information on some of the items that I have designed that may be of interest to the group that will enhance your listening experience on the bands. Everett N4CY https://www.icloud.com/iclouddrive/05098Uoz4s1Mo19gRTsehNv7g#Offerings_of_N4CY

Hello all, I'm clipping an AlexTune onto a W2LI magnetic loop antenna. I'm puzzled by something: the point at which it shines brightest is consistently about +20 kHz above what a NanoVNA (and the transceiver) indicates is the bottom of the SWR curve (on 40M). What explains this? Is this a case where lowest SWR isn't necessarily where the maximum RF radiation is? Defective unit (would love to know what's inside)? User error? Thank you! -Todd

I have attached a link the has information on some of the items that I have designed that may be of interest to the group that will enhance your listening experience on the bands. Everett N4CY https://drive.google.com/file/d/1M1TlnssNm14-WS8GezcaqfgKbInCoqVb/view?usp=sharing_eil&ts=6782a096

Dear UK ham, I am building my Wellbrook copy with the PCB from Everett. This PCB fits into the original enclosure: 20mm 2 Way Through Junction Box - White. Unfortunately it is out of production with Schneider Electric as of Octiber 2024, but I found an online shop who showed they them in stock. https://www.yesss.co.uk/20cjb3w-through-circ-box-20mm-white?srsltid=AfmBOoooTalVKjWkxRpBFixaMhVVYykoOg-boRw4p2jJQpOlXUnGcOUT I am not sure if those are still commonly used in the UK, but perhaps you can give me advice. Tnx in advance! 73e Michael PA5M

Good morning, I'm wondering if anyone like me has made a full working Wellbrook 1530 LN amplifier based on the schematic found in the files section named "Wellbrook_Loops.Kicad_sch." with smd 2SK932 jfets (but others schematics are very similar) I'm asking because I made a couple of them over time, one even with the original 2SK715 jfets but in the end they have the same problem, that is, they seem completely deaf up on LW and MW to the shortwave range, where they work much better...a classic amplifier with only two transistors (BFU590QX) works regularly. I tested the jfets (taken from the European electronics e-commerce portal TME) and they are all ok, the absorption is normal at about 115 mA at 12V. The toroid windings are the ones described on the schematic: input P3/S12 (plus the two single turns) secondary with crossed wires - output P9/S5. Test loop hang from a tree in my garden at about 2 mt. from ground. I'm adding the link with a short video and I've put two photos of the boards so you can see the construction. Thanks in advance, F. /g/loopantennas/album?id=299839 https://youtu.be/yhv-jP-9Ero

Not affiliated with them but have used them ever since I was trying to solder and wondered why I couldn't focus close enough. As you age you inevitably run into the issue. The OptiVISOR is one solution: https://doneganoptical.com/product/optivisor/ I am posting this because I just got the OptiLOUPE accessory and it works really well. I could read the markings on a SOD-123 diode: https://doneganoptical.com/product/optiloupe/ As I understand it the OptiVISOR has glass lenses and the OptiVISOR LX has plastic lenses. The plastic lenses may not be as good, so bear that in mind if you are looking. I have the DA-4 lenses for the OptiVISOR and they work well for soldering surface mount components. I have the DA-5 lenses on the way. Thought I would see how they compare to the DA-4. -- =================================================================== Mike M

Hi All, I saw an interesting article. an amplifier using a 2N5109 at the bottom of this page. https://www.microchem.fr/ayet/atlas/hf_amplifier.html It has a 3.3V zener diode and a 3.3k resistor to make a bias voltage. It looks simple and stable, seems to work well in LTSPICE simulations. I have a question. I have never seen a direct bias style like this. Is there any problems? 73, Hisami 7L4IOU

Merry Christmas to ALL from Los Angeles, California !!!! 1). Need a Formula for designing an "L Impedance Matching Circuit" for matching 50 Ohms to an Antenna with a known Antenna Input Impedance ( Z ). Any Web Sites for referral or Formulas ? So far have not found any. 2). Question: In winding a Toroid there are many ways to get a Turns Ratio of 3:1, such as - 6 Turns to 2 Turns, 9 Turns to 3 Turns, etc. Is there a "GENERAL RULE" for determining the number of Turns that is best ?? [ I believe EACH winding on the Toroid needs to operate below it's Self Resonant Freq inorder to act as an Inductor. Maybe for a "Broad Band" Toroid, a Higher Number of Turns ( increases R ) is better because it lowers the Q = Xl / R of the Inductor ? Any Comments and Help would be APPRECIATED !!!! THANK YOU Garey Wittich

Pa0FRI has become a silent Key. Anyone using any of his loop amplifier designs or data may well want to archive or save it before the web page disappears. There is also a lot of other general useful information his page. https://www.pa0fri.com/ Henry

Thinking of getting on but am wondering what users in the US have done for an enclosure? The round shape was made to fit into 20mm electrical trunking junction boxes that are available in Europe. Could save me some time if anyone has it figured out. Thanks

I sold a bunch of multicouplers this month and still have one left. The multicoupler can power an active antenna with its internal bias-tee, and feed 1 to 4 receivers. If interested contact me at thomas.b.seeger(at)gmail.com 73 Tom /g/loopantennas/files/VE3PSZ%20Multicoupler%20General%20Notes.pdf

I want to add this post to Martin's MLA-30 thread, but it is locked. Hence, my starting this new topic. I know the MLA-30+ has been done to death where evaluation is concerned, but I can't resist jumping into the fray! So, here's the link to my eval. Thanks for reading!? 73, Chin-Leong Lim, 9W2LC.

I tested three different transistors in the Ikin Norton 9 dB circuit--2SC5551, BFU590QX, 2SC3357 (all SOT-89 package). I used Everett N4CY's PCB. All were tested at 12.0 volts supply and bias set for 70 mA. Since the 2SC3357 has a max 12 volts Vceo; this circuit with 12.0V supply and 70 mA had 10.3V emitter to collector so is running below the Vceo 12V limit. IMD tested with my standard 3/4 MHz test tones set for 0 dBm each tone at output of the preamp----2IMD checked at 1 and 7 MHz; 3IMD checked at 2 and 5 MHz. P1dB tested with 50 ohm load at 1 MHz. Gain swept with DG8SAQ VNWA--all three had fairly flat response from about 50 kHz-30 MHz. Noise figure tested on HP 8970B. 1. 2SC5551 IMD--1 MHz +93 dBm OIP2, 7 MHz +89 dBm OIP2. 2 MHz +50 dBm OIP3, 5 MHz +49.4 dBm OIP3. P1dB--0.585 watts, +27.7 dBm. 10 MHz noise figure 1.82 dB. (The transistors are from what I purchased several years ago when Rochester Electronics still had them.) 2. BFU590QX IMD--1 MHz +84.5 dBm OIP2, 7 MHz +83.5 dBm OIP2. 2 MHz +50.1 dBm OIP3, 5 MHz +49.3 dBm OIP3. P1dB 0.585 watts, +27.7 dBm. 10 MHz noise figure 1.87 dB. (I got the transistors from mouser.com, NXP made them.) 3. 2SC3357 IMD--1 MHz +89 dBm OIP2, 7 MHz +89 dBm OIP2. 2 MHz +49.9 dBm OIP3, 5 MHz +49.6 dBm OIP3. P1dB 0.63 watts, +28 dBm. 10 MHz noise figure 2.15 dB. (I got the transistors from digikey.com, EVVO (Chinese) made them.) All three transistors gave similar IMD and P1dB. 2SC5551 is no longer available but the other two are currently being made. If you're careful not to exceed the 2SC3357 Vceo 12V max, it would also be suitable. 73, Steve AA7U