开云体育

Hello from your friendly neighborhood moderator. If you see spam here, or something you think feel is spam or so far off topic that it does not belong here, please email me at [email protected] and include a link to the message on the website. Please do NOT mark as spam, especially don't mark it as spam in your email program. Due to the measures taken by many/most ISPs, groups,io will boot you from any group that you mark as spam. Even if your email program puts it in your spam folder without any action by you, if you allow it to delete it without marking it "not spam", Groups.io will boot you from the group. No actions by me. It is not my choice that such a nuclear option be used. However, so many people sign up for a list then either forget the did, or decide they want off but somehow find it "easier" to start marking the messages as spam... or lazily allow their email program or provider to mark as spam and don't bother correcting it. Also, while we're talking about this sort of thing, I'm not your momma. If you want one of your own messages deleted, if you want to stop following a topic, if you want to change your email preferences in some way, please do so yourself. 99.9% of you seem to be self-sufficient, but I moderate a couple dozen groups with tens of thousands of members. Thank you, and stay healthy. -- Steve Greenfield AE7HD

When something is posted in Files, the only way to view it is to download it. If you have not put a description, if I have to download a file to look at it to tell what it is, I'm deleting it. There are too many JPGs in there with only a date code as a name with no or only a cryptic description. I'm deleting them. Think about someone going into Files or Photos a few years from now, not having your emails discussing it in mind. Will they know what it is based on the file name and description? Is it useful for them? Files and photos not in folders are a bit like going to a common meeting space, throwing pictures and little bits of stuff everywhere, then just leaving it for someone else to figure out and clean up. It is rude and inconsiderate. If you only need to share a file temporarily, consider posting it on a file sharing site and putting the link in your message. Thank you, -- Steve Greenfield AE7HD

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

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

After talking with Dave Evans, he noticed that my load resistance slider was at minimum and thought that my radials were too long. He suggested that I raise and shorten them. I raised them from on the ground to 18 inches high and shortened them to 15 feet. That did it! Thanks to Dave! I am satisfied with the antenna and will be able to do better with it after spending more time with it. FX QTH CALL DATE TIME AZ K9AY LOAD AZ LOOP COMMENTS 363 NJ RNB 3 19 1330 330 92-73=19 450 225 87-69-18 30 miles 860 PA WWDB 3 19 1330 310 90-68=22 300 000 80-65=15 990 PHL WNTP 3 19 1330 330 95-65=30 350 000 84-63=21 same tower locatiom 1060 PHL KYW 3 19 1330 320 95-60=35 350 000 78-60=17 same tower locatiom 1150 DE WDEL 3 19 1330 101-86=28 650 240 107-79=28 1210 PHL WPHT 3 19 1330 0 106-83=23 650 010 96-78=18 PERSEUS END

I have just installed an Aziloop and I do not get good nulls - 10 -15 dB on 50 -100-mile ground wave signals, Loop is 13' on long side, 8' on short side and PVC mast is 15 feet. Radials are on the ground below the loop elements. It is fed with about 200' of RG6 cable and the supply voltage is 12.7 volts. I have a SAL-20 antenna 40 feet north of the AZI. I can get 15-30 dB nulls with it. I have a 60 foot self-supported welded steel tower with a large 10–40-meter Mosley beam at the top 42' east of the Azi. Antennas are in the middle of a 1.5 acre lot - no other buildings or metal nearby. Ground elevation is 15 feet ASL. Could these two other antennas be affecting the poor null operation on the Azi? Any suggestions would be appreciated. 73, Bill, WA2DVU Cape May, NJ 609 425 8651