Lex dealing with RFI and home misfortunes

[mount intermod]

Original subject was :
Re: UNID stations 6915-6926 22 Aug 2022 0000-0050 UTC

i understand what Lex is going through.. i have amateur growers, over the years, with cheap, unshielded growing ballasts..ruin my amateur hobby for years before the laws here, in this state, were modified..

good luck,  hoping you find a quieter location

edit by Ray Lalleu : indeed  very interesting replies, but this was worth a thread of its own, and moved to a different forum (Hope I won't hurt anyone by changing the subject, splitting and moving the topic)

[Pigmeat]

I had one two houses down. He'd get so stoned he literally had wrecks pulling out of his driveway. The cops picked up on the skunky smell on him and got a search warrant and that was the end of Stinky and his grow op. He got a stiff sentence as he and his wife had two small kids.

[Zoidberg]

Howdy, @Sealord @ChrisSmolinski and all. Long time, no me. Busy with life stuff since 2015.

'scuse the late reply. The week I dug the radios out of the closet in August this year, my apartment was flooded nine days out of two weeks, through the first week of September. Took that long for the landlord to finally hire a proper plumber, rather than trying to cheap out by having the maintenance guy try to fix it with a drain snake.

Seems to be fixed, for now, but I'll be cleaning up for the next month. The water was literally wall to wall in every room, up to an inch deep, seeping through the baseboards and out the exterior wall between the concrete foundation slab and brick mortar. Fortunately it was all relatively clean warm water, straight from the upstairs neighbor's shower, with the exception of one nasty day. Every morning. But it's infuriating that the landlord shrugged it off for two weeks before getting serious about fixing the problem. And jacked up my rent 43% earlier this year. I'm looking for another place now.

And my old wifi router quit working reliably at the same time. I was using my phone and data plan to post logs, but I wasn't spending much time browsing or checking for replies and messages. ATT sent me a free replacement modem, but it took me almost two weeks to find time to hook it up this week. And another couple of hours for ATT to set it up remotely. But it seems to be working now.

Anyway, I needed a break from cleanup chores, reruns on TV, and mostly needed to get out of the apartment. SWLing seemed like the perfect excuse to get outside. Again.

i understand what Lex is going through.. i have amateur growers, over the years, with cheap, unshielded growing ballasts..ruin my amateur hobby for years before the laws here, in this state, were modified..

good luck,  hoping you find a quieter location

My battles with RFI were almost legendary on the forum and chats a decade ago. Goes with the territory for almost everyone in urban and most suburban areas since the 1990s when the FCC gave up on trying to regulate RFI-spewing imported electronics. I've actually heard worse RFI on some online SDR and remote controlled older receivers, mostly located in big cities around the world. Kinda puts things in perspective.

Unless I move back to a rural area, I have no illusions about finding a low RFI environment. Back around 2008-2012 when I was playing radio almost every day, my solution was a variety of homebrewed passive loop antennas. They were ugly, cheap and some worked remarkably well. One was dubbed the Fugloop, because it looked like nothing but a hunk of old but good quality TV grade coaxial cable wound around a closet door. It was directional at the feed point so I could aim it by opening or closing the door. I still have the materials but had to disassemble the loop years ago to prep for a building inspection. Most landlords and inspectors tend not to understand DXing. And that particular loop was gawdawful ugly. But functional and quiet.

My best loop was an outdoor stealth loop, rigged to a nearby wooden fence. It nulled out the worst source of local RFI very effectively. It was dirt cheap, using magnet wire that was such small gauge it was practically invisible; a TV balun that should not have worked on the HF band at all, but did; and TV coax run along the ground adjacent to the apartment exterior wall, shoved into the crevice between the dirt and brick wall to sort of hide it. Worked great for a couple of years until a new maintenance crew discovered it and tore it down. Fortunately it was mostly found materials -- the coax was fished out of the dumpster; the TV balun had been in my junk bin for years; and I think I paid a dollar for the magnet wire.

I haven't decided whether to keep or sell my Palstar R30 receiver, but if I keep it I'll rig up another homebrewed passive loop. I tried the Palstar this week with a random wire antenna and an RF Systems EMF antenna I got from the legendary late, great Al Fansome about 12 years ago. Great portable antenna, but can't compete with the local RFI. That's why I've mostly saved that antenna for field trips, where it's easy to toss up a tree. The Palstar is a great, very basic, no-frills receiver, but like most AM receivers for MW and HF, it needs an antenna suited to the local challenges.

So mostly I'm using my portables. The classic Sony ICF-2010 was noted for the AM sync capabilities, but what I like most about it is the directional quality of the built in telescoping whip. I just aim the tip of the whip at the noisiest RFI source (usually parking lot and apartment lights). That usually orients the whip more or less horizontally, parallel with the ground, which tends to reduce RFI anyway. It reduces signal a bit as well, but it's more pleasant to listen with minimized RFI, so even faint signals from pirates are audible.

I've tried external antennas with the Sony ICF-2010, but mostly they just increase noise. And the mini phone jack isn't really suitable for most antenna feedlines using shielded cable. I might eventually rig up a portable passive loop with a thinner shielded feedline and mini phone plug, but ... probably not. It works fine as-is with the whip.

The cleverest homebrewed antenna trick I've tried was the Villard loop (http://www.tsf-radio.org/forum/im/145279k3mt_-_villard_anti-jamming_antenna.pdf). Here's a video demo of the Villard loop I recorded several years ago. https://www.youtube.com/watch?v=32Hy0RAnkBk

The video and notes below the video link to the instructions for making the loop. It's simple and cheap. All you need is stiff backing board like gatorfoam or poster board, aluminum foil, newspaper (or any large sheets of paper), and scotch tape. Google around for the Villard loop and you'll find a bunch of mentions and tips for making one.

The loop is basically just a crude capacitor that takes advantage of the capacitance effect that plagues most small portable radios. Usually that capacitance effect is a PITA for careful tuning and adjustment of whip antennas, because merely touching the radio, or even waving a hand near it or changing our body position, can affect the reception and static. But the Villard loop turns that into an asset it can use to null out the worst local static.

Unfortunately it doesn't work as well on my larger portables, which are better shielded and resistant to the capacitance effect. But it works very well with smaller portables.

My old Villard loop got torn up a few years ago, but I plan to make a larger one that will reach the 40m or so band. I suspect a Villard loop the size of a queen or king size bed could be used down to the 75-80m bands as well, although it was be unwieldy and difficult to store.

My old antenna design book had plans for a more sophisticated indoor loop, about the size of a box fan, that uses metal strips rather than delicate foil as the capacitance link, and a proper mechanical tuner to fine tune the rig. Depending on design and size those can be used down into the AM medium wave band. Basically the same effect, but a bit more involved in construction and materials cost.

[Ray Lalleu]

A long posting by Lex, I'm still have to read it carefully,
and think it's worth many replies, but that should not change the initial topic about 3 stations around 6920 kHz.

[Sealord]

Don't sell the Palstar; I still have my R30CC (mine is an early version w/12v option on the coax) and will never part with it.  I know the radio has mixed fans, but it's a great receiver for what it does.

[Zane]

Don't sell the Palstar; I still have my R30CC (mine is an early version w/12v option on the coax) and will never part with it.  I know the radio has mixed fans, but it's a great receiver for what it does.

Agreed!

Z

SL!

[Pigmeat]

Didn't Drake make the Palstar line? I remember seeing them advertised and thought, "Boy, look at the tuning knob on that baby!"

I read an article about the Villard Loop in a ham mag years ago. The guy was a CW op and lived along the Gulf Coast. He built one on cardboard that he used with a portable receiver to copy other op's. His had two modifications, it used copper foil and he used a tuning capacitor. He had a wire out the window he used for the QRP rig he ran on 30 meters.

He spoke of how well it worked in the summer static and storm season, mentioning that he was so engrossed in making contacts one night that he didn't know a thunderstorm was on top of him until he saw lightning flashes out the window.

The lesson with this loop, if you're a ham, is don't use those big ear muff headphones. This is a quiet loop.

Just like Al to buy an antenna when he could have made his own. He was the Little Lord Fauntleroy of DX'ing. He knew real radios though. Refined tastes.   

[Zoidberg]

Didn't Drake make the Palstar line? I remember seeing them advertised and thought, "Boy, look at the tuning knob on that baby!"

I chatted with Paul Hrivnak on the phone about 10-12 years ago, after first getting the Palstar receiver. I was curious about some design details, including what appeared to be a doodad inline with the Hi-Z antenna input to reduce the risk of static shock in real longwire antennas, particularly in dry summers in windy areas.

If I'm recalling correctly, Paul was an engineer for RL Drake for awhile and (again, if I'm recalling correctly) was also involved in the design of some of the smaller portable Lowe receivers (HF-150?) that were popular in the early 2000s-2012 or so. Later, Lowe also basically rebranded a Palstar, with permission from Palstar.

But the Palstar was a totally independent design from Drake. When the two are compared they aren't similar in size, build, or diversity of features. The Palstar has only two filters, no AM sync, etc., but rock solid AM performance on MW and HF and seems immune to overloading or images. I seem to recall some minor legal kerfluffle between Drake and Palstar about 10-15 years ago over some design issues, but I can't find those references online now. If I'm recalling correctly the dispute was over Palstar's use of the same metal speaker cabinet used by Drake for its optional external speaker. the Palstar just reoriented the cabinet/grille differently in essentially the same cabinet. I think Palstar later switched to its own speaker cabinet design.

I haven't kept up with the industry in the past decade and might be misremembering some details.

[Zoidberg]

Just like Al to buy an antenna when he could have made his own. He was the Little Lord Fauntleroy of DX'ing. He knew real radios though. Refined tastes.

I think Fansome was enamored of the miniature beer cans attached to the RF Systems EMF antenna.

Seriously, though, IIRC, the "magnetic transfer" canisters on the various RF Systems antennas were some sort of impedance transformers intended to physically shorten a wire antenna, and reduce some manmade RFI. RF Systems sold these in the EMF and a Windom style.

[ChrisSmolinski]

I like to divide received RFI/QRM/etc. into two categories:

1. Signals flowing on the transmission line / coax cable shield - common mode signals.
2. Signals actually "in the air" so to speak, being picked up by the antenna.

The first case is where common mode chokes (aka ferrite cores) on the transmission line can help. They can reduce or eliminate currents flowing on the outside of the shield. It's almost always worthwhile to give this a try as it's pretty easy, and due to the proliferation of computers, switching power supplies, etc. in the house it is inevitable that you have at least some common mode issues.

You do need to pick the right kind of core material to use, with enough turns of the coax through it, to be effective. There's other posts here on the HFU detailing what to use. I've *never* found the simple clamp on ferrite cores to help. Never. Not on HF anyway.

For the second case, no number of ferrite cores or other magic is going to help. Radiated RFI that is being picked up by your antenna looks exactly like a signal from a radio station. The ferrite does not know the difference.  Special coils or inductors or transformers or what not in the antenna aren't going to do anything either. There are a few things you may be able to do:

If you can make the antenna directional, you can null out, or at least reduce the intensity of, the offending signal. Of course this is more difficult on HF than VHF/UHF due to the wavelength size. And if you've got RFI from several directions, or it is the same direction as the station of interest, you are out of luck.

Antenna placement can also help. Get it as far away from the house (or your neighbor's house) as possible, as well as power lines (both for RFI and safety reasons).  Try a few different locations / orientations and see what works best for your stations of interest.

Use coax cable to feed the antenna, and possibly start feeding the antenna further from the house. Yes, this means a smaller antenna, but a smaller antenna that picks up a lot less RFI wins.  So rather than run your long wire directly from the shack window, maybe start it from a nearby tree, and run coax from the shack to the tree.  And of course properly feed the antenna with an appropriate transformer and ground it correctly - see other posts, for example: https://www.hfunderground.com/board/index.php/topic,74042.0.html

And of course try to identify any RFI sources and deal with them. If they're in your house, you can fix them. I find this tool to be excellent for fixing RFI generators. Usually only one application is required:

[Zoidberg]

Yup, I've never found those single bead ferrite chokes to do much good to reduce household RFI to the radio, including on commercially made shielded cables supplied that way. For the various audio and patch cables I've used at times, including power supply cords, I've had better results looping at least two, preferably more, layers of cord through ferrite chokes at both ends.

Those single bead chokes probably do okay for the intended purpose with computers, camera and video gear, etc. But for reasonably clean radio reception, especially on the HF spectrum, I've found it helps to wrap two or more loops through ferrite chokes large enough to handle the cord/cable diameter.

With some shielded cables, I've had pretty good results winding the receiver end of the cable multiple winds, neatly, around a hollow core of some kind. A large empty pill bottle, stiff cardboard tube leftover from kitchen wrap, an empty plastic cylindrical container -- whatever you have handy. Wrap all the extra cable around the tube, neatly, single layer, and tape it in place. Often that reduces common mode noise. But on some HF frequencies it'll also reduce the desired signal. Experiment to find what works best in your area.

One problems I've noticed with using ferrite chokes or those hollow core type chokes is an increase in the capacitance effect. The receiver and antenna become much more sensitive to where we sit, stand or even moving our hands around. That also varies with the frequency we're tuned to. Very hit or miss approach to reducing household and local RFI.

And a directional antenna can help. I've rigged up simple homemade small loops with the null aimed at the worst neighborhood offenders, usually outdoor lights around the apartment complex and parking lot. Pretty much the same theory for the crude but effective Villard antenna, which has a sharp null for local RFI, while remaining sensitive to skywave propagation.

And I've noticed the telescoping whip on my Sony ICF-2010 has a fairly sharp null off the end. So if I aim the whip at the worst neighborhood RFI source, it'll reduce RFI enough to copy fairly weak stations. I don't get that effect with my smaller Panasonic portable.

I don't recall whether my old Magnavox D2935 has that null off the end of the whip. I need to load it with D-cell torpedoes and try it again outdoors. Great radio, other than the thin plastic layer over the buttons. That plastic layer with the button labels has deteriorated so badly it's unreadable and I'm mashing buttons by memory after owning that radio for about 30 years. Too bad because that Netherlands-made Philips/Magnavox D2935 was one of the best large portables for shortwave and MW DXing. I've had it running 24/7 for years and it's still chugging along, although the built in lamps burned out many years ago.