SWL - Mission Impossible? Nearby power lines and transmitters

[Phil_KD0SCJ]

I'm considering a return to the SWL world. I have some money, I think I want to look at SDR. I have some interesting antenna possibilities. But, before I even start down this road, I have to consider the problem of nearby interference. I have the following concerns:
1) A 115KV AC transmission line bordering my property. The best distance I can get from this powerline is about 150 feet.
2) Nearby broadcast transmitters, the closest an FM transmitter roughly 1/2 mile away, many other AM/FM/TV towers within 5 miles.
3) Fairly limited options for antenna height because of the power line and space required for guy wires if I go that route.

At one time, I had a Kenwood R-1000 which I bought used, so condition not entirely certain. I ran coax to a longwire running North/South, 80 feet long, about 20 feet in the air and used a balun on one end to connect the coax. I was able to get one or the other of the WWV stations pretty clearly any time of the day or night. I was able to listen to many of the Christian superstations. I could catch the occasional HAM on 20 Meter, but that was about it. I ultimately lost interest... you can only listen to WWV for so long. So, I sold the R-1000 years ago.

My question to you all is this: I'm ready to drop as much as $1,000 on a new radio/antenna setup. But, with all these potential sources of interference, do you think I would get substantially better reception, or is this simply mission impossible?

As a follow-up, before I spend that money, would it make sense to buy some kind of meter to actually measure the interference, and if so, what would you recommend?

If this is a go, I will have many more questions, but I need to know first if I am just wasting my time on something that cannot be done.

Thanks in advance for your thoughts!

~Phil

 

[GB46]

I'm considering a return to the SWL world. I have some money, I think I want to look at SDR. I have some interesting antenna possibilities. But, before I even start down this road, I have to consider the problem of nearby interference. I have the following concerns:
1) A 115KV AC transmission line bordering my property. The best distance I can get from this powerline is about 150 feet.
2) Nearby broadcast transmitters, the closest an FM transmitter roughly 1/2 mile away, many other AM/FM/TV towers within 5 miles.
3) Fairly limited options for antenna height because of the power line and space required for guy wires if I go that route.

I`m almost in the same boat. I live in a corner suite of a wood frame apartment building on the top floor. My longwire antenna should be enough, but can`t be put outside. It wouldn`t help anyway, because two sides of my apartment are directly across from major power lines, which in my case can`t be more than about 30 feet away. Sometimes I can`t hear WWV on any of its frequencies if the signal isn`t strong enough to make it over the noise. There`s also a shopping centre directly across the street, and its parking lot lighting is another source of interference. The directional properties of a loop antenna would not help, because there`s noise in just about any direction.

This isn`t meant to discourage you, but I`m losing interest in shortwave, and have instead been spending more time monitoring local VHF & UHF stations with my scanner -- no noise problem there.

 

[ka3jjz]

But for the OP, a loop might be the best option, as well as adding some additional filtering - perhaps in the form of a passive preselector, since his sources of BC interference is so wide, frequency wise. Get that loop as far away from that power line as possible - if you can do 150 foot, great.

Never point the antenna - whatever you use - at the power lines. All you'll pick up is noise that way

Mike

 

[Dirk_SDR]

For SWL I would also recommend a wideband active loop antenna with low gain combined with filtering against:
- Powerlines: Good highpass filter for a frequency of e.g. 30 kHz (if you want to listen from LF upwards)
- FM: https://www.nooelec.com/store/sdr/sdr-addons/flamingo-plus-fm.html
- AM: https://www.nooelec.com/store/sdr/sdr-addons/flamingo-am.html
- transmissions from out of HF amateur bands: www.sv1afn.com/en/product-category-4/HF-Amateur-Bands-Preselector.html
... and perhaps also with better grounding.

My situation isn't that bad, but I am e.g. near a railroad with heavy 16,6 Hz and in a building made of concrete (including flat roof). No antennas allowed outside.
The challenge for me is to deal with my specific situation.

 

[Phil_KD0SCJ]

Thanks everyone. I have a strategy of sorts now. The big ticket item in all of this was the SDR itself. But, I could use a low-end SDR and at least get a grasp of the situation. So, I have ordered the following:

RTL-SDR V3
Flamingo FM filter
RTL-SDR AM filter
HIZ-HPF Highpass filter
MLA-30+ loop antenna
Misc cables/adapters

This will give me plenty to start with, I can try something things with the loop antenna and filters to empirically work out the noise situation.

Again, many thanks,

~Phil

 

[ka3jjz]

The preselector Dirk suggested would just be for the ham bands and would severely attenuate anything outside of them (as it should). A better choice;

MFJ-1046, RECEIVER PRE-SELECTOR, 1.6 - 33 MHz

MFJ Receiver Preselector, 1.6-33 MHz IN STOCK! READY TO SHIP! MFJs new Passive Preselector has extremely high dynamic range! It improves the performance of nearly any HF or shortwave receiver/transceiver. It vastly improves the most expensive receivers. Especially helpful to those with...

mfjenterprises.com

you would not need all that additional filtering with this. Think of a tunable 'filter' when considering a passive preselector. If you are on 6 Mhz, for example, you will not hear much of anything from the AM BC band.

Mike

 

[Phil_KD0SCJ]

Yes... and part of my interest is in or nestled near the HAM bands so I'm not going that particular filter.

The MFJ-1046 seems worth a look, ordered that too.

 

[Boombox]

I'd buy a good Tecsun portable first, at an affordable price. Take a listen. See just how bad the QRN and RFI may be. That will give you an indicator of the noise level you may be dealing with.

As for the rest of it, you'd obviously want an antenna that is directional and noise-reducing, which I think loops are capable of doing. If you have the money, that would be the way to go.

 

[vagrant]

I have high voltage lines and the tower near the back of my property that is closer than 150’. Using a handheld AM radio I tuned off freq and extended the antenna. I had more noise near my home than at the back of my property near the power lines. I setup an Off Center Fed antenna in the backyard. It is an inverted V around 10 meters at the apex with the legs/wire running parallel to the power lines. I use that antenna to TX/RX around the world on multiple bands.

Things that helped were an inline Dunestar AM BCB filter, as I have two nearby AM stations. The biggest help was an inline RF choke at the antenna feed point. It reduced my noise floor about 2 S units which is significant. I use the MyAntennas choke balun. Some people need to use another RF choke just before their receiver as well, I do not.

To complement that antenna I ran another Off Center Fed perpendicular to the power lines and use a switch to select each one. This perpendicular antenna has a lower noise floor. With their opposing lobe directivity, I may see two S unit gain when I switch between them.

For VHF/UHF I use a discone antenna with numerous filters inline to block strong RFI. I have problems with AM, FM, NOAA, and the worst is a paging system at 152 MHz. I use two filters just for that. I use PAR filters to suppress the RFI and they definitely help. Recently, they put cellular antennas on the tower and built a cinderblock structure under the tower for the equipment. Yeah, good times with RFI filtering here.

I also use an SDRPlay receiver with those antennas. For AM filtering with that I use the NooElec Flamingo AM filter as it is a notch filter and not a HPF.

 

[Phil_KD0SCJ]

Using a handheld AM radio I tuned off freq and extended the antenna.

Brilliant! I do have a handheld radio AM/FM/NOAA with an extending antenna, plus a YAESU FT-270R VHF/UHF transceiver with a long whip antenna. I can go to various empty frequencies and scout things out. Thank you!

Yeah, my closest radio tower, like I said, about 1/2 mile away. It has been there for probably 50 years or more. Funny little sideline, the city decided to build a new water tower right next to it... like, less than 100 yards away. The water tower tank is steel, and you would not believe the array of wires and gadgets on that water tower to try and make the water tower and radio tower get along.

Thanks for the new comments!

~Phil

 

[timetraveller]

Phil,

Testing the waters with an inexpensive SDR is the way to go. Don't get discouraged with RFI.

I was about to quit altogether due to encroaching and unsolvable RFI problems and I discovered the Loop on Ground antenna.

The Loop on Ground Antenna - the "LoG" (kk5jy.net)

Now I DX from mediumwave all the way to 30 MHz.

Have been in the game for 62 years. A ham for 58.

Bill, WE7W

 

[Phil_KD0SCJ]

I'm back... I think if I told the entire story so far, I would start to get into something for the SDR forum. I'm still waiting on the antenna. What I have for far is the RTL-SDR with the included di-pole antenna via a high-pass filter and the MFJ-1046. I'm able to receive quite a few stations across most of the spectrum, including WWV 15MHz at an SNR > 30 dB... which I would not have thought possible with the cheap rabbit ears that came with the radio. An unexpected source of noise was a USB cable I was using for the dongle. It's all very encouraging. This is on the level of performance I had with my R-1000 and a longwire. I would love to try this dongle on the longwire but it came down in a storm and is currently under about 3 feet of snow.

Thanks again everyone.

~Phil

 

[Dirk_SDR]

I'm back... I think if I told the entire story so far, I would start to get into something for the SDR forum. I'm still waiting on the antenna. What I have for far is the RTL-SDR with the included di-pole antenna via a high-pass filter and the MFJ-1046. I'm able to receive quite a few stations across most of the spectrum, including WWV 15MHz at an SNR > 30 dB... which I would not have thought possible with the cheap rabbit ears that came with the radio. An unexpected source of noise was a USB cable I was using for the dongle. It's all very encouraging. This is on the level of performance I had with my R-1000 and a longwire. I would love to try this dongle on the longwire but it came down in a storm and is currently under about 3 feet of snow.

Thanks again everyone.

~Phil

My experience is that "my own" noise at home is much harder to fight against than against the noise from outside. I have ferrite beads on most power and USB cables, sheath current filters on antenna coax cables just in front of the receiver.
I'm still improving power supply, filtering and grounding with the "trial and error" method as a kind of never ending story...

 

[Phil_KD0SCJ]

Yes, I think that will be the case with me as well. I'm starting to put together a plan. I'm going to get an SMA 50 ohm terminating cap and work on internal noise first, and then start identifying external sources in the room and move my way out. What I would really like to do is get my outside antenna(s) working again but it's going to be a while before I get a good warm stretch to start clearing snow. Any reasonable person would wait until summer.... but no, not me.

 

[Phil_KD0SCJ]

I do appreciate all the great comments, I have a one-month report for you:

I am now running an SDRPlay RSPdx. To the antenna side, I bought a MLA-30+ and did some modifications, and then got it outside and in the open. I bought a $10 VHF/UHF whip, and made a DIY air-band antenna. The RSPdx has three selectable antenna inputs, so there they are.

On the computer side, I have the RSPdx connected to a Raspberry Pi 400, which is a linux box, and all it does is relay USB traffic back and forth between the RSPdx and my regular windows PC via my LAN network. The idea is to eventually have the Raspberry Pi in an outbuilding at the antennas.

Results: Generally very good. The RSPdx has a built in broadcast band notch filter, and it doesn't play around. The AM tower close to me just disappears along with everything else in the commercial AM and FM bands.

My other concern was the 115KV transmission lines. The MLA-30+ is a loop and I have to aim it through those lines to go East. I am not experiencing any issues there either. They may not be active... I'm not going to climb up the poles to check.

I have had good reception from Asia, Europe, South America and Canada on SW broadcasts and HAM SSB on various bands. Next up will be a 124 foot longwire system, but again, this spring at the earliest.... which up here really means June before you can think of digging a hole.

Once again, thank you. This was an easy thing once I got going. Any questions, I'll do my best to answer.

 

[KB2GOM]

If you have a problem with noise, I have had very good luck with one of these: Jock reviews the BHI Compact In-Line Noise Eliminating Module

Remember, there are two components to the signal-to-noise issue: the strength of the signal (antenna possible fix) and the noise (DSP possible fix).

I have no financial connection with BHI, bought one of the units with my own money, and now use it constantly.

Cheers, Jock

 

[DXerPaulAK]

I'm considering a return to the SWL world. I have some money, I think I want to look at SDR. I have some interesting antenna possibilities. But, before I even start down this road, I have to consider the problem of nearby interference. I have the following concerns:
1) A 115KV AC transmission line bordering my property. The best distance I can get from this powerline is about 150 feet.
2) Nearby broadcast transmitters, the closest an FM transmitter roughly 1/2 mile away, many other AM/FM/TV towers within 5 miles.
3) Fairly limited options for antenna height because of the power line and space required for guy wires if I go that route.

At one time, I had a Kenwood R-1000 which I bought used, so condition not entirely certain. I ran coax to a longwire running North/South, 80 feet long, about 20 feet in the air and used a balun on one end to connect the coax. I was able to get one or the other of the WWV stations pretty clearly any time of the day or night. I was able to listen to many of the Christian superstations. I could catch the occasional HAM on 20 Meter, but that was about it. I ultimately lost interest... you can only listen to WWV for so long. So, I sold the R-1000 years ago.

My question to you all is this: I'm ready to drop as much as $1,000 on a new radio/antenna setup. But, with all these potential sources of interference, do you think I would get substantially better reception, or is this simply mission impossible?

As a follow-up, before I spend that money, would it make sense to buy some kind of meter to actually measure the interference, and if so, what would you recommend?

If this is a go, I will have many more questions, but I need to know first if I am just wasting my time on something that cannot be done.

Thanks in advance for your thoughts!

~Phil

Depending on how powerful the FM transmitter is 1/2 mile away you might have a small problem with overload in some parts of the SW bands. I know i know.. sounds odd.. but in my 20 years of workin in broadcast media from 100 watt Fms to 5KW AM's to 100KW FM's.. ive had a small problem with overload on SW when extremely close to FM transmitters.

If youre 5 miles away from AM, you shouldnt have much of a problem at all with a single station.. if some transmtiters are 50kw, then maybe......where you could maybe have a problem at 5 miles if more then one station mixes, liek i had in Wyoming....two stations by themselves cause you no problem on their own individual frequencies but they mix together and that mixing product creates an issue

In Laramie, WY.. 10kw on 1210 and 5kw on 1290 were 1/4 mile from each other and about 1 1/2 miles from me.. i had problems on 1210, 1290 but they also mixed and i had issues in a few other spots on the dial

 

[iowajm780]

I would like to get back in the SWL game, but where I live the noise floor is crazy high. There is so much WWV you can take if you know what I mean.

 

[DXerPaulAK]

I would like to get back in the SWL game, but where I live the noise floor is crazy high. There is so much WWV you can take if you know what I mean.

Get a tecsun pl880, a portable SW antenna like a loop and if you live in iowa.. just drive out into the country around dark

 

[mbott]

I wouldn't let the potential for noise to hold you back. I've struggled with RFI for years, yet I get enough enjoyment from the hobby to put up with it. I've even made available a kiwiSDR from my location. Most days the RFI wins but come evening time it is generally quite listenable. Today it's not bad relative to other days. As mentioned above, a loop helps fight the noise.

--
Mike