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HF/MW/LW General Discussion General discussion on monitoring the HF (High Frequency), MW (Medium Wave), and LW (Long Wave) spectrum (0.5 - 30 MHz)

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  #21 (permalink)  
Old 07-12-2012, 6:20 PM
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Thanks Ridgescan--How do I ground that longwire?
Do you have a cold water pipe very nearby the antenna feedpoint? What do you have as a groundpoint within 8' of your antenna feedpoint?
I have mine grounded to the metal fire escape system which is bolted to the steel frame of the building. I also have it grounded to the cold water pipe which knocked the noise down to nothing on MW but made no difference on SW. Between both grounds I have optimal MW quieting.
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Old 07-13-2012, 12:11 AM
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I'd be thrilled to death if just one time I could get a station east of the Mississippi. I have yet to do a proper MWDX session is probably why-I need to have patience.
The trick is getting around your local 'pests' since the band is so crowded these days. There are plenty of good east coast targets, so make a short list and check those frequencies often looking for odd conditions or perhaps a pest station being off the air (for whatever reason). Another trick is to beg/borrow/build an antenna phaser. It can be a commercial unit (MFJ) or home brew (Google: LC antenna phasers). SUPER simple to build, you just need two antennas to phase. They could be two wires, two loops, or one of each. Piece of cake!
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Old 07-13-2012, 7:36 AM
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Well I know sometimes I'm a little thick headed--must be age. I understand grounding but usually there is a second wire. So do I just attach the antenna wire itself to ground or do I attach another wire to the antenna wire and then to ground. I have the wire running up the eave of the house.
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Old 07-13-2012, 8:57 AM
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Well I know sometimes I'm a little thick headed--must be age. I understand grounding but usually there is a second wire. So do I just attach the antenna wire itself to ground or do I attach another wire to the antenna wire and then to ground. I have the wire running up the eave of the house.
The ground gives the antenna wire something to work against so by adding a ground instead of just running that wire straight from the radio, you kind of have a "dipole" antenna which is quieter noise wise than just the wire straight off the radio. You use coax for a feedline- so the ground attached to the coax braid sort of protects the signals coming in from RF noise around your home
I would feed the wire with 50 ohm coax-attach the antenna wire to the center lead of the coax, then attach the coax braid to a ground like a cold water pipe, or an 8' rod driven into the dirt right near the antenna feedpoint. You have any idea if you have good grounds like this very near where the antenna wire comes in from outside?
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Old 07-13-2012, 9:02 AM
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Thanks ridgescan. I have a good grounding source near the antenna feed so I will give that a try.
It should stop raining one of these days so I can get outside to work.
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Old 07-13-2012, 10:59 AM
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Thanks Ridgescan--How do I ground that longwire?

For my 45ft longwire I am running 75ft of 75ohm coax from the receiver to the longwire antenna atop a 30ft tower. I ground the coax at the bottom of the tower and run a ground wire up the tower to ground the coax where it connects to the longwire. This works great for my setup but everyone's is different so experiment.
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Last edited by 7designs; 07-13-2012 at 11:03 AM..
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Old 07-13-2012, 11:13 AM
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The trick is getting around your local 'pests' since the band is so crowded these days. There are plenty of good east coast targets, so make a short list and check those frequencies often looking for odd conditions or perhaps a pest station being off the air (for whatever reason). Another trick is to beg/borrow/build an antenna phaser. It can be a commercial unit (MFJ) or home brew (Google: LC antenna phasers). SUPER simple to build, you just need two antennas to phase. They could be two wires, two loops, or one of each. Piece of cake!
You wouldn't happen to have a schematic would you? All I am finding is commercial units and designs for ham.
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Old 07-13-2012, 11:22 AM
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duplicate
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Old 07-13-2012, 12:33 PM
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Sorry I'm a little late to the party, but I used to get WOR from New York, WSB from Atlanta, some station from Virginia, and some station out of Windsor, Ontario from Canton, OH. There was also a station from the Albany/Schenectady area in New York, WGY, I think, but the only thing I remember about it was a catchy jingle for a carpet retailer.

Last edited by bge1234; 07-13-2012 at 12:35 PM..
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Old 07-13-2012, 5:16 PM
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For my 45ft longwire I am running 75ft of 75ohm coax from the receiver to the longwire antenna atop a 30ft tower. I ground the coax at the bottom of the tower and run a ground wire up the tower to ground the coax where it connects to the longwire. This works great for my setup but everyone's is different so experiment.
Hey 7D hey does that ground make your noise quieter? Because from what I have read, at 30' it may be acting like a vertical leg of your 45-footer. The way I have gathered, you need to keep it short like where the coax enters the house. I bet you have awesome reception though so it maybe doesn't matter.
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Old 07-13-2012, 10:07 PM
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Probably not the RIGHT am station. But heard a French program on 183 LW possibly Europe 1 @ 0251 utc tonight. Lot of static.
As of now 0319 utc listening to Medi 1 on 171 very clear out of Morocco
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Last edited by bmlure; 07-13-2012 at 10:20 PM..
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Old 07-13-2012, 10:25 PM
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You wouldn't happen to have a schematic would you? All I am finding is commercial units and designs for ham.
You're right, it is hard to find a good article.

You'll need two antennas. Two wires, or a wire and a loop.

For two wires, build a parallel tuned circuit that will resonate in the medium wave band and put that in series with your wire antenna. (confusing, eh?)

Use what parts you have on hand, but if you pull the variable cap and loop stick antenna out of some portable AM radios, then you're good to go.





(eliminate C4 and the radio gets hooked up at the bottom)

Make one circuit for both antennas and put them on a switch, or use clip leads so you can choose antenna A, B, and BOTH.

The phasing is very frequency specific in this circuit, so tune into the station that you want to make GONE. Let's say 720khz WGN. Peak the circuit on antenna A for max S meter reading. Switch to antenna B and do the same for WGN. For best results the S meter reading should be the same on both antennas. Many times it is not, so a 50k ohm variable resistor (potentiometer) in series with each of your antenna leads allows to you make them the same. Next, flip your switch to BOTH (or attach both antennas to your receiver at the same time with clip leads) and -carefully- adjust your variable caps until you null WGN. If WGN is S9 on each antenna, you should be able to drop it down to S3 or even make it dissapear (!) leaving weaker stations underneith in the clear.

If you have a wire and a tunable loop, do the same thing. Adjust both your wire and loop for max signal strength, connect them both together, and adjust the tuning to null your 'pest'.

When you change frequencies, you'll have to re-tune your circuits, but this method works VERY well and I've used it to log many Mexican and South American stations when they normally would be covered up by stateside stations. I've done it during the daytime on my local stations and have heard stuff at sunset that I could never hear otherwise. The loop/wire combo is very potent and I've also had good results phasing a wire vs a vertical. Go out to a park, lay out some wires on the ground (BOG antenna) and phase those together. The limits are only in your imagination.

Super cheap DX!

There are other ways to phase antennas (broadband), but this is the simplest way, and very effective.

http://www.youtube.com/watch?v=GRT16Fqp4UM

I've had a couple MFJ-1026s and they work very well. The problem at my QTH is that the surface mount components get overloaded by my local stations and I get slop across the whole band. When I use BIG antennas, it gets even worse, so I have better luck using my home brew phasers.

I use big variable caps and big coils, but use what you can get your hands on.

Have fun!

(if you're into FM DXing also, you can phase FM yagis with a slightly different circuit for the same effect. Getting sneaky to log the rare ones!)
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Last edited by k9rzz; 07-13-2012 at 10:47 PM..
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