Two Stations on 530 kHz with caveat, new Superloop Antenna

[MavamQ]

Hi all,
I just got a 70 ft x 25 ft Superloop antenna put up, far from finished, but I got first listen yesterday.
I'm in the panhandle of Florida.
Today I'm trying to ID a strong S8 signal on 530kHz, after searching, I have decided it is R. Enciclopedia
out of Cuba. But I see there is a Turks and Caicos station and a Canadian on the same frequency. So I grabbed my portable,
thinking I might be able to null the signal to determine the direction. Nope, I don't get a hint of that signal.
However, I do get a different station at low level that nulls to the East/West (90*/270*) direction. Turks and Caicos
would null at (125*305*). And oddly enough, if I get the radio ferrite bar close to the lwire of the superloop antenna the station
I receive on the portable gets much louder, and still no hint of what I think is R. Enciclopedia that I get on my in shack radio.

Can anyone explain this phenomena of my antenna sending one station down the feed line to the shack and have a different
signal be enhanced by the antenna wire itself?

Also, what 530 station would null (90*/270*) from my Panama City Fl location?

A little more explanation, I have an FM transmitter that I plug into my shack radio, so I can monitor the audio.
When out in the yard with my radio in FM mode I hear my shack radio, when I switch my portable to AM, I hear the
unknown 530kHz. I hear two different stations.

More, I have a terrible buzz on my portable in the house, thus I go out in the yard. I have a isolated it to one circuit breaker,
but have not gone any further, yet.
Thanks all, Mikek

Icom R71A and Sangean 818 portable
Superloop Antenna The SuperLoop: A super-sized terminated corner-fed broadband loop.

 

[wenzeslaus]

the only station I'm coming up with anywhere in US or Canada on 530 is CHLO in Omtrio. a null at 90-570 degrees would suggest the station is north or south of you so maybe that's it. anyways if you listen long enough they should have a station ID and usually AM stations mention their call letters quite frequently.

Radio Station Finder: Search Results

let's assume that's what it is for troubleshooting.

the radio in the shack gets R. Enciclopedia on the superloop.

the portable radio doesn't get R. Enciclopedia and still doesn't using induction from the superloop.

the portable radio gets CHLO by itself, and through induction with the superloop.

I think the answer is that the superloop has a gain lobe pointing more towards CHLO and less toward R. Enciclopedia, and the radio in the shack hears R. Enciclopedia because it's more sensitive, while the portable radio is less sensitive and doesn't hear it.

by the way, loop antennas have magnetic flux lines that encircle the wires of the loop so when you put a portable radio with bar antenna near it the orientation can be greatly skewed. that might not help with orienting the antenna but might help reducing confusion on which direction has null or gain when using coupling the portable radio with induction.

 

[MavamQ]

The only station I'm coming up with anywhere in US or Canada on 530 is CHLO in Omtrio. a null at 90-570 degrees would suggest the station is north or south of you so maybe that's it. anyways if you listen long enough they should have a station ID and usually AM stations mention their call letters quite frequently.

I expect you meant 90-270, however, we have some confusion. When I say I have null at 90-270, I mean I point the long part of the rod 90-270 and the station nulls, that means the station is 90-270. East or West.

Radio Station Finder: Search Results

let's assume that's what it is for troubleshooting.

More a curiosity at this point.

the radio in the shack gets R. Enciclopedia on the superloop.

the portable radio doesn't get R. Enciclopedia and still doesn't using induction from the superloop.

the portable radio gets CHLO by itself, and through induction with the superloop.


I think the answer is that the superloop has a gain lobe pointing more towards CHLO and less toward R. Enciclopedia, and the radio in the shack hears R. Enciclopedia because it's more sensitive, while the portable radio is less sensitive and doesn't hear it.

I don't think it is CHLO, I'm in Florida and and my antenna is setup to null to the North.
This is temporary, and because my existing feedline was to short to set it up for the other direction.

by the way, loop antennas have magnetic flux lines that encircle the wires of the loop so when you put a portable radio with bar antenna near it the orientation can be greatly skewed. that might not help with orienting the antenna but might help reducing confusion on which direction has null or gain when using coupling the portable radio with induction.

It's a thought and I'll test is, but, I don't think the bar antenna will have much affect on the 190ft of wire I have in the air.
I'm going out now to test that.
Ok, I did that, I monitored my shack radio via my FM link and put the bar antenna along the loop wire, it had zero effect.
On a side note, I about 10 feet from the antenna, I laid my radio on the feedline, the signal picked increased a lot, I wrapped four turns around the radio and the meter read 4 S units with a no noise signal. I'm not sure I like my feedline picking up and radiating signal. I hope it is the extra 3 pairs in the Cat5 cable and not my the pair with my actual signal to the radio.
Given some time I'll ID that signal on my portable.

 

[wenzeslaus]

the bar antenna does not affect the loop.

the magnetic flux lines are bent around the wire of the loop.

if you have a station straight north of you, a vertical loop (such as the AN-100 for example) is oriented so the wires are north-south so it picks up the station. a portable radio with a bar antenna on the other side of the room is also oriented so the wires on its bar are north-south, the bar is east-west. as the radio approaches the loop and you set the radio right next to the loop, you might have to turn the radio up to 30 degrees to get the best inductive coupling between the bar antenna and the bent magnetic flux lines.

now, you have a big humongous Super Loop that takes up your whole yard. you don't know where the station is at. with the portable radio next to the Super Loop and is Humongous Super Magnetic Flux Lines, the orientation of the radio very well may not indicate the true direction to the station.

 

[wenzeslaus]

On a side note, I about 10 feet from the antenna, I laid my radio on the feedline, the signal picked increased a lot, I wrapped four turns around the radio and the meter read 4 S units with a no noise signal. I'm not sure I like my feedline picking up and radiating signal. I hope it is the extra 3 pairs in the Cat5 cable and not my the pair with my actual signal to the radio.

it probably is. however it's radiating RF, and the signal is >>>>>stronger than whatever it picks up so that's not a problem.

I have spent a LOT of time building various loop antennas and that is a good sign. that means it's a very strong antenna. getting 4S of noise floor means when you do get a signal it's going to be very strong. the antenna is like using a megaphone on your ear. it amplifies noise and signal, not just signal alone. it's up to the radio to provide noise discrimination, selectivity, etc.

you probably have already seen this, but wrapping more or less turns around your radio improves coupling and may need as little as 1 wrap or even no wraps, just lay it on the wire. too many wraps chokes the signal. reconfiguring the antenna so 3 wraps is optimal probably gives you the best signal/noise ratio.

really if the purpose is to connect to the radio in the shack, I'd use a coax cable to reduce RF loss. if you have to use CAT5 you might get some inherent capacitance, notice that AM loop antennas for a home stereo have twisted lead wires to reduce that.

 

[MavamQ]

Well I got a bit of an ID. At the top of the hour in both English and Spanish the announcer went through the stations that re-broadcast the audio of WFKF 1070. I have one of those that is a local on 1430. Is there any chance I get a signal on 530 from a 1430 broadcast?
Second the station in Tallahassee is on 1070 is it possible the they are broadcasting a sub-harmonic on 535 where my radio only
tunes 530 and 540.
I did call the 1070 station and ask if they have any re-broadcast on 530kHz, they assure me they don't.
I did question that maybe my amplifier was putting out this signal, so I shut it down. That made no difference.
Just to be sure, I completely removed the amplifier, No change I still have a strong 530 signal from my feedline.
and to double check I moved away from my antenna and extended a 50ft extension cord and wrapped some
turns around the radio, It improved the weak 530 re-broadcast of WFKF, but didn't show what I think is R. Enciclopedia.
Any Ideas.

 

[MavamQ]

it probably is. however it's radiating RF, and the signal is >>>>>stronger than whatever it picks up so that's not a problem.

With directional antennas you don't want your feedline to add any signal to your desired pattern. As long as this signal doesn't get to the radio, that's fine, in this case it is does not seem to be. Although I do have some additional choking going on at the radio end of the feedline to further reduce any feedline ingress..

I have spent a LOT of time building various loop antennas and that is a good sign. that means it's a very strong antenna. getting 4S of noise floor means when you do get a signal it's going to be very strong. the antenna is like using a megaphone on your ear. it amplifies noise and signal, not just signal alone. it's up to the radio to provide noise discrimination, selectivity, etc.

I think we have a failure to communicate.
My antenna is receiving a strong signa,l probably 530 in Cuba, my feedline is radiating a signal on 530 unknown from where, but not 530 in Cuba. That unknown signal is not from my antenna, proven by what I said in my previous message about removing all connections from the amp and the antenna.

you probably have already seen this, but wrapping more or less turns around your radio improves coupling and may need as little as 1 wrap or even no wraps, just lay it on the wire. too many wraps chokes the signal. reconfiguring the antenna so 3 wraps is optimal probably gives you the best signal/noise ratio.

Yes, I first noticed the feedline antenna affect by laying my radio on the wire, then I added 4 turns and got an S4 signal, adding more turns increased the signal but it got very noisy.

really if the purpose is to connect to the radio in the shack, I'd use a coax cable to reduce RF loss. if you have to use CAT5 you might get some inherent capacitance, notice that AM loop antennas for a home stereo have twisted lead wires to reduce that.

The reason I use Cat5 is because it has been shown to reduce feedline ingress. This is especially helpful on phased antennas the have a null that can be spoiled by signal added by the feedline.
The Cat5 capacitance is actually lower than RG-8/U 15pf/ft vs 25pf/ft. Twisting wire increases capacitance slightly.

"Twisting wires causes a slight increase in resistance due to the extra length of wire wound in the twisted pair. On the other hand twisting reduces the characteristic impedance as a transmission line as it increases the capacitance by reducing the distance between the conductors." The quote is from Quora, but it is accurate as to the way I understand.

Thanks for playing along, Mikek

 

[wenzeslaus]

okay

 

[MavamQ]

the bar antenna does not affect the loop.

the magnetic flux lines are bent around the wire of the loop.

I missed this response. When you said, "when you put a portable radio with bar antenna near it the orientation can be greatly skewed. I was confused, I thought you meant the Superloop antenna would be skewed and I doubted that. Now I see you meant the null of the portable will be skewed and I'm 100% sure that will happen.

if you have a station straight north of you, a vertical loop (such as the AN-100 for example) is oriented so the wires are north-south so it picks up the station. a portable radio with a bar antenna on the other side of the room is also oriented so the wires on its bar are north-south, the bar is east-west. as the radio approaches the loop and you set the radio right next to the loop, you might have to turn the radio up to 30 degrees to get the best inductive coupling between the bar antenna and the bent magnetic flux lines.

now, you have a big humongous Super Loop that takes up your whole yard. you don't know where the station is at. with the portable radio next to the Super Loop and is Humongous Super Magnetic Flux Lines, the orientation of the radio very well may not indicate the true direction to the station.

I missed this response. When you said, "when you put a portable radio with bar antenna near it the orientation can be greatly skewed."
I was confused, I thought you meant the Superloop antenna would be skewed and I doubted that. Now I see you meant the null of the portable will be skewed and I'm 100% sure that will happen.
Mikek

 

[MavamQ]

okay

I can't tell if you are being sarcastic or if you agreed with everything I said. I would much rather discus things, as I'm always learning and
I expect I can learn from you.
Is there something I said in that response that you disagree with?
Thanks, Mikek

 

[WA8ZTZ]

Is there any chance I get a signal on 530 from a 1430 broadcast?

Yes.

A true image may be heard at double the IF of your receiver below the station transmitting frequency.
You have a local WLTG AM 1430 there in Panama City.
Your portable has an IF of 450kc.
2 x 450=900.
1430 - 900=530.
My guess is that what you are hearing on 530 is an image of WLTG.

 

[MavamQ]

This sounds very plausible! Is there any way I could confirm that?
Thanks, Mikek

 

[MavamQ]

I have another radio with a 455 IF, but it doesn't have a readout. If I use it to get the unknown signal on my feedline, don't touch the tune knob, then go into the shop use my frequency generator and my frequency counter and find the radio is tuned to is 520khz does that confirm it. Or might another radio be more immune to this mixing product? I guess I'll find out tomorrow.
Thanks, Mikek

 

[WA8ZTZ]

You actually confirmed it by copying the TOH ID.
As a double check, tune another radio to 1430 and see if it parallels what you are hearing on 530.

Otherwise, different radios may not produce the same mixing result unless you are very close to WLTG
(in which case you may find spurs at other frequencies as well).

 

[MavamQ]

Oh, they do match as to the audio. But I didn't know at the time there was no other re-broadcast on 530 from WFRF.
I'm pretty sure you have this correct, but I will try anther radio tomorrow.
The funny thing is this 1430 station is only 125 watts! The tower is about 6 miles from my house.
Also, the null position lines up with the location of 1430 from me. Now, I'm even more convinced you are correct.
Thanks, Mikek

 

[MavamQ]

I took my 455kHz IF radio out along with my 450kHz IF radio, I wrapped 4 turns of feedline around both and compared the audio
when they were both tuned to 530Khz.
The 450kHz If radio received the 1430kHz mixing product and the 455kHz received the 530 Cuban Station.
The Sangean ATS 818 had mixer product, the GE SuperRadio iii did not. I thought the SuperRadio would have more problem with mixing products.
Mikek

 

[WA8ZTZ]

Just for kicks...

Tune the Superadio down to 520 (if properly aligned it will tune down that far) and see if you hear the image.
2 x 455=910.
1430 - 910=520.

Placing the 818 near the loop antenna feedline is apparently overloading it.
The 818 has an RF stage and 2 IF stages whereas the Superadio has a tuned RF stage and 4 IF stages.
Thus, the Superadio has more filtering and is probably better at rejecting spurious signals.

 

[MavamQ]

I did tune the super radio down to 520 with my signal generator and a frequency counter.
Then tested it with 4 wraps of the feedline.
And I did not receive any signal.
I think you figured this one out!
Thanks for your help on this. It was kinda fun to sleuth out.
Mikek