开云体育

Hi Everyone, A little background, I have been into SWL for some time and recently got back into the hobby, and went down the slippery slope of SDR ;-) I have a KiwiSDR2, and started with an MLA30+ which was OK. I tinkered with it, and broke it :-( and then decided to try an Apex Radio 303wa-2 which works great with a small LNA, however the local noise in my urban area is awful. So, after some deliberation and another hit on the credit card, I purchased a fresh off the production line, LZ1AQ AAA-1C. I was excited to see how it performed, because I can never seem to get much more than 10-20db of SNR, depending on the time of day. (on the Apex Antenna) After some tinkering with what I already had around, and some more disappointing results had obtained some annealed copped pipe from a local HVAC workshop, who kindly gave me their off cuts, and its super easy to work with. Initially I had a single loop with mixed results, and yesterday built this (I want to say monstrosity, however It's not really), an orthogonal loop. I didn't put a lot of science into the build, more feeling, however readying various notes on how these are built, suggests the most important thing is the material (like pure copper) and its area. The loops are suspended on / in the PVC pipe and the shaft is metal which stops about where you see the first zip tie under the amplifier. My issue is the performance. No more than 20db at silly o'clock (when I am sleeping) and SNR: 8 dB (0-30 MHz), 8 dB (1.8-30 MHz) right now, at 7.30am. I've moved the antenna around the garden, however this seems to be the best place. There is a lot to unpack here, however my first consideration is if I have configured the Amplifier correctly, as I found the instructions quite confusing. Some more info. I'm not using switches on the control board yet (that's to be made up) So I am shorting the relevant pins on the connector for now - which I confirmed working OK by checking the continuity of the A and B connectors. When shorted the relays open and when not shorted, the relays close. The FTP cable is an outdoor rated Cat6 shielded. It's a PITA as it's thick, but it's all I had. The PSU is an iron core 12VDC wall plug, which is delivering 14v no load, and the amplifier gets all of that from the control board. Martin (G8JNJ) who is a guru of all things loop, suggest I should post in here :-) Many thanks for looking and look forward to your feedback. (all and any welcome - as I'm still learning this craft) Cheers Sean (ZL2006SWL)

sean@... added the photo album Orthogonal Loop : My Orthoganal loop - made from 2 x 15.9mm annealed copper tube connected to an LZ1AQ - from active-antenna.eu. Its a start!

Looking for a SAL-30 (no mast needed) . Nick VK9DX vk9dx@...

Hi All, I came across "The R&S HE-015 active antenna" by chance. http://rxcontrol.free.fr/Receivers/HE015/ In the pictures there, the combiner seems to be "anzac JH-6-4". http://rxcontrol.free.fr/Receivers/HE015/HE015-Pieces.jpg I have some home brewed Small Loop, Active Dipole and Mini Whips, so I would like to try combine them. The key component JH-6-4 is also listed on DigiKey, but price is exorbitant! https://www.digikey.jp/en/products/detail/macom-technology-solutions/JH-6-4-BNC/18676343 the datasheet here https://shop.richardsonrfpd.com/docs/rfpd/JH-6-4.pdf?srsltid=AfmBOoo9ngmV8rtJTMEBZRmWjag49Ts2j2uSTN3ZRI1OO0waGWgH5SZl Does anyone know what the JH-6-4 or equivalent is made of or how it works? I imagine it is probably a device like this. https://www.qsl.net/va3iul/Homebrew_RF_Circuit_Design_Ideas/0-and-180-deg_Couplers.gif What do you think? tnx & 73, Hisami 7L4IOU

Hi all and thanks for accept me in the group. I'm building a magnetic loop antenna for TX and I slightly follow the instructions in https://www.nonstopsystems.com/radio/frank_radio_antenna_magloop.htm and another sources. I've finished the main loop with the capacitor and its rotator and now I have to choose a coupling loop configuration. There are basically 2 variants: unshielded and shielded (aka Faraday loops). According to the link I've wrote I'd like to use the shielded F variant because it seems to be better cancelling E-fields in horizontal and vertical polarization. But there are some people that think both variants work the same. I'm in doubt with this. Any advice or experience? Thanks in advance. Regards.

Good morning out there. I have a Pixel loop and the amp has lost all gain, although RF still makes it through but without any gain. Does any one know of a source for a schematic of this amp? I have exhausted every resource that I can think of but to no avail. I can fix this guy but I need a road map. Thanks Joe K8FC

I just finished another batch of receiver multicouplers. If anyone need one, contact me at thomas.b.seeger@gmail(.com) As usual, free shipping to anywhere in the world. 73 Tom /g/loopantennas/files/VE3PSZ%204-Way%20Multicoupler%20General%20Notes.pdf /g/loopantennas/files/VE3PSZ%208-Way%20Multicoupler%20General%20Notes.pdf

The following photos have been updated in the Azi-Loop Self-Supporting Structure for Transportable / DXpedition Use photo album of the [email protected] group. GroundMount-ScrewType.jpg By: Guy Atkins <dx@...>

anilkraj@... added the photo album Ferrite Loop for NDB : Ferrite Loop Antennas for NDB hunting The following photos have been uploaded to the Ferrite Loop for NDB photo album of the [email protected] group. IMG_1281.jpeg By: anilkraj@...

The following photos have been updated in the Azi-Loop Self-Supporting Structure for Transportable / DXpedition Use photo album of the [email protected] group. Azi-Loop_Complete-2.jpg By: Guy Atkins <dx@...>

Hi all, I was looking for a simple design for a MW loop and came across this design in the file sections here... However, upon closer examination there appears to be a fundamental problem in this circuit from what I can judge (non-engineer!). /g/loopantennas/files/Cornell%20Loop%20Article The feedback/regen is to a tap in the antenna coil as opposed to a separate feedback coil. When the pot wiper is set all the way to earth, it would effectively short out 20% of the antenna coil completely changing the resonant frequency from what I can see. Also having a 5k resistor to earth from the antenna coil is not ideal for the Q of the L/C circuit either I suppose? Once again, I'm not an engineer but this circuit is a bit puzzling to me. Grateful for your thoughts and guidance. Anil / SM0MFC

I just finished building a few of my improved version of the LZ1AQ, in a box with wing nuts and a few ALA1530 LZ1AQ replacement loop amps. If anyone is interested please contact me off list at everettsharp (at) aol com. Everett N4CY

Hi been playing around with ft8 on 160m.. on psk reporter heard in vk etc.. ( when band open.) tx and rx antenna is a Marconi T. However rx in said directions from here is poor. ( see below.) Live on dartmoor national park ( just,) nice low noise floor. Nice and high (asl) I have crossed parallel loops, delay lines and Lz1aq (5551’s) preamps for rx if I wish. Thing is on 160 the Maroni T beats them.. Now I need to state, my garden is on a BIG slope ( Dartmoor) my rx array is 10m below gnd level of house basement.(20m below roof line.) My garden slopes to west.. Excellent results from south to north, due to clear take off, but though north/ east to south not so good due to antennas below gnd level of house. so i need to improve rx on 160 towards VK etc. Thinking another singular loop on roof ( have pole already erected. Or an short vertical eprobe. Have never used an eprobe, so no idea of performance.. Any thoughts?? please see my qrz page for pic of garden to get idea.bottom of garden is to west of house. Bottom of garden ( gnd) is 20m below roof line. Simon g0zen

I have a SAL-20 antenna for sale. Contact me off list for details. 73l Bill, WA2DVU Cape May. NJ 609 425 8651 bill.riches@...

The following items have been added to the Files area of the [email protected] group. /MODIFIED AMRAD PREAMP - 20 MARCH 2025.docx By: W0LEV <davearea51a@...> Description: Build and technical evaluation with measurements of the Modified AMRAD high-Z input preamp for E-Field probes. Dave - W?LEV

I made the corrections that Martin mentioned and I also add the Bias adjustment procedure to the posting and deleted the 2 original postings. Everett N4CY

The following photos have been updated in the Azi-Loop Self-Supporting Structure for Transportable / DXpedition Use photo album of the [email protected] group. LCU Interior.jpg By: Guy Atkins <dx@...>

Hi All, I found an interesting site, there a archive of the defunct "ham radio" magazine. https://www.worldradiohistory.com/Archive-DX/Ham%20Radio/ I have been reading this article intensively for the past few days. "active antenna preamplifiers by R.W.Burhans, ham radio May 1986" pp.47-54 https://www.worldradiohistory.com/Archive-DX/Ham%20Radio/80s/Ham-Radio-198605.pdf There are things I can't understand. Please someone tell me what they are? About "inductive feedback and input capacitance" that says "A circuit that can reduce the input capacitance and improve the linearity for MOSFETs involves a noiseless feedback method" and "with the FET input capacitance reduced to pratical levels comparable to ..." Does this mean that the inductance and capacitance cancel each other out? Or does the NFB current or voltage physically reduce capacitance? About "active notch" I have tried to the BC band notch between the Probe and the Amplifier or between the Small Loop and the Amplifier, but it does not work well. It seems to be difficult with High-Z or Low-Z line. Putting it in the NFB line looks like a good idea. Have you tried it? Did you get good results? Actually, the MiniWhip I made at the end of last year looks exactly like fig.2 circuit and works well for VLF. it running at http://ja7kbr.proxy.rx-888.com:8073 and I hope to improve it. I have no electrical or physics education (other than Ham radio), so please forgive my naive question. 73, Hisami 7L4IOU

The following items have been added to the Files area of the [email protected] group. /Modified AMRAD eProbe Antenna.pdf By: Everett N4CY <everettsharp@...> Description: Active eProbe antenna

The following items have been added to the Files area of the [email protected] group. /AG5RT/LZ1AQ amplifier noise reduction.pdf By: Mark Whittington AG5RT <mark-whittington@...> Description: LZ1AQ loop amplifier noise reduction I ran an LTSPICE noise analysis of the original LZ1AQ circuit connected to a 3.3 uH loop. I also performed some bench measurements to verify the SPICE results. The analysis and measurements both indicate placing 47 uH inductors in series with the 51 Ohm input emitter bias resistors cuts input referred noise by 2 to 3 dB. This is a substantial reduction. Gain is little effected. Loop diameter can be reduced while maintaining the same input-referred noise level as the original setup. The LTSPICE listings share this directory. Mark AG5RT