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Just tested the LZ1AQ amp with BFU590QX. Performance equivalent to the 2SC5551. As with the 2SC3357, the max voltages are lower for the BFU590 than for the 2SC5551. However, just like with the 2SC5551, the voltages in the LZ1AQ circuit have plenty of margin. Both Mouser and DigiKey have the BFU590QX in stock. -- =================================================================== Mike M

Hi all, I have been reading with lots of interest the post by AA7U Steve on his findings and modification experiments with his GA-450. Steve, did you find that after doing the modification to power the RF board directly with 12 volts DC, that there was less noise generally, or was that only in this particularly troublesome MW to 3MHz section? I have been having fun experimenting with my as yet unmodified GA-450 and, providing I turn my radio's gain way down low, have been rather impressed with the results. It's an improvement over the telescopic whip and it's nice to be able to have some directivity. However, the gain is rather excessive in my opinion and I wonder if anyone has any ideas how that might be reduced......? I have no experience with varactor-tuned loops, but have buils lots of other types, and my latest activie antenna for MW and HF can have the gain adjusted by reducing the voltage to the AMP. I'm guessing a similar arrangement will not have quite different results with the varactor set-up and just lower the maximum tuned frequency........ The photos you have posted in the files section Steve will be invaluable if I decide to do any modifications. But it would be sad to lose it's portability. Anyway, hope someone can offer a little bit of advice! Thanks. Adam (M6RDP

With the recent talk about oscillation I thought I would share a recent debug. Summary: have multiple ferrite bead types on hand. I made a PCB for the Ikin Norton Amp: /g/loopantennas/files/Wellbrook%2050%20ohm%20Norton%20Preamp/Ikin%20Norton%20Amp%20sch.PNG.jpg It is a 2-layer PCB with ground fills. I built one using 2SC3357 transistors and it worked. I built a second using 2SC5551 and it oscillated at 660MHz. It also did not amplify. I checked and double checked the transformers but could find no difference between the two boards, but then I found the amplification problem: one end of the T1 primary was soldered but had not melted the enamel on the wire so it was not actually connected. But it still oscillated. The ferrite beads I used are Laird MI1206K310R, which are about 41 ohms at 1GHz. I tried replacing them with 68 ohm resistors but no change. I tried replacing the 10pF caps with 39pF, still no change. I then put the 10pF caps back and put Laird LI1206H121R-10 ferrite beads in and it tamed the oscillations. The new ferrite beads are around 135 ohms at 1GHz, so that is what it took. So don't be afraid to use high fT transistors, but make sure you have a ferrite bead in the design as well as a variety of ferrites to test. I just looked at the data sheets. The ZTX327 used in the original has an fT of 800MHz, the 2SC3357 is 6.5GHz and the 2SC5551 is 3.5GHz. So even though the 2SC3357 has a higher fT than the 2SC5551, it did not oscillate. -- =================================================================== Mike M

Hello, lots of great info here. I am new to the group IO format, just created an account. I have been paging through the topics and tags but I cannot seem to find anything that deals directly with the shape of the loop material. I have been debating building an upgraded receive only loop. I see most loops are made of round material, either tubing, wire, coax etc.. i am wondering if using sheet metal cut to a certain width then passed though a 3 pin roller to achieve the correct diameter would be OK? The 3 pin can also take up to 3/8" solid or hollow round stock. How wide would be too wide? Thanks a lot

If anyone is interest in LZ1AQ boards, Transistors, or Built and Tested LZ1AQ amps you can contact me off list. at everettsharp (at) AOL com Everett N4CY

Seeking advice for “upping my receive game” during Field Day Contest operation this coming summer. On Field Day, multiple operators are usually grouped physically (and socially) close but some don’t always respect band schedules & bandpass filters and which means I generally I can talk better than I hear hear because of interstation receive interference. On FD I transmit 20-10M bands using a 17’ vertical + Base autocoupler + directional radials all mounted at 10’ AGL that gives fine directional transmit but my receiver is overloaded with other on-site contestors. I’m wondering if a receive-only loop located as far away from other antennas (up to 1000’ allowed) and taking advantage of loop directionality might help? 1. - Would commercial 1M receive loops be directional enough on 10-30M to be helpful? 2. -Would locating the loop to the edge of the 1000’ contest area, far away from other Hams, be woth the effort? 3. - Would the LZ1AQ likely function OK over that 1000’ length of CAT interconnect? Or, maybe a better approach is the rather expensive DX Engineering NCC-2 Receive Antenna Phasing Systems DXE-NCC-2 to null out local noise with a 2nd local-only antenna? https://www.dxengineering.com/parts/dxe-ncc-2 I’d appreciate anyone’s experience or ideas! 73…John

In case anyone is interested, I bought an LZ1AQ type amp from Everett before Christmas and finally got it up today. I'm using a 4 foot loop made from 1/2 hardline, fed with about 50 feet of RG6, and 8 feet AGL. I was fat, dumb, and happy with my homebrew amp based on the G8CQX design with a pair of 2N5109 transistors and a 3 foot loop of the same material but as a mobius. The difference is amazing. Just as a point of reference for myself , I am now receiving solid copy NAVTEX on 518Khz from Labrador and seeing signals from Greenland. Those stations where not even a squeak previously. Florida and PR boom in like they are local. I am in coastal NJ. NDB stations are all over the place. 160 and 80 are a pleasure with an S1 noise floor and very little reduction in signals from my transmitting antennas. Good stuff!

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