End fed dipole question

[prcguy]

Another thing you can try that helps in some cases is a good common mode choke in your feedline where the coax exits the house. If there is any RF interference riding on your coax shield from stuff inside the house to the antenna this can reduce the problem.

I use a different antenna than the OP (ZS6BKW) that has a transition from ladder line to coax using a 1:1 balun. I recently upgraded the 1:1 balun from a very basic unit that probably has poor common mode rejection to one that has well over 30dB rejection over most of the HF range. I could immediately see the improvement in the noise floor on my radio's spectrum display and it's not a subtitle change.

I used to have a continuously varying noise floor over any specific HF band with lots of wide bumps and peaks plus some CW birdies all over the place. The new choke basically flattened out all the wide bumps and peaks to a flat noise floor leaving only some of the CW birdies, meaning much of the junk was traveling up my coax to the antenna. I have a lot of computer stuff near my main HF radio and the feedlines pass right by computers, monitors, routers and lots of switching wall warts. I had no real complaint of my average HF noise floor at home but also had no idea it could be improved this much.

The 1:1 balun I built that reduced my noise is very similar to this one : CMC-230-5K - MyAntennas.com and I did a lot of research and testing with various ferrite cores to try and duplicate the performance.

For lower power operation but still good for legal limit this one is probably the best on the market: CMC-130-3K - MyAntennas.com

Its hard to say if one of these would improve your situation but I would recommend borrowing something similar and trying it to see.
prcguy

 

[W2JMZ]

Another thing you can try that helps in some cases is a good common mode choke in your feedline where the coax exits the house. If there is any RF interference riding on your coax shield from stuff inside the house to the antenna this can reduce the problem.

So on the exterior wall where the cord enters the house is where this common mode choke would go? Or on the wall where the cord exits the house?


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[prcguy]

My opinion is place it downstream of anything in your house that could introduce noise onto your coax but keep it far enough away from the antenna so it can snuff out noise before it reaches the antenna. For me this was down the coax about 20ft from the radio and on my roof where coax transitions to about 40ft of ladder line to the antenna elements.
prcguy

So on the exterior wall where the cord enters the house is where this common mode choke would go? Or on the wall where the cord exits the house?


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[W2JMZ]

My opinion is place it downstream of anything in your house that could introduce noise onto your coax but keep it far enough away from the antenna so it can snuff out noise before it reaches the antenna. For me this was down the coax about 20ft from the radio and on my roof where coax transitions to about 40ft of ladder line to the antenna elements.

prcguy

Ahh that makes sense now. So the links you suggested is an example of what you're talking about?


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[prcguy]

Yes, but 1:1 choke baluns are not created equal, look for one that advertises the restive choking value above maybe 5k ohms or the amount of choking greater than 30dB.
prcguy

Ahh that makes sense now. So the links you suggested is an example of what you're talking about?


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[Ed_Seedhouse]

The laws of alternating current do not allow an antenna to work without a counterpoise, period. No counterpoise no current. If you do not have a formal counterpoise designed to act as one there will still be a counterpoise, just not where you want it to be. See this link: end fed 1/2 wave matching system end feed

You can't argue with physics. Well you can, but you will always lose.

 

[W2JMZ]

The laws of alternating current do not allow an antenna to work without a counterpoise, period. No counterpoise no current. If you do not have a formal counterpoise designed to act as one there will still be a counterpoise, just not where you want it to be. See this link: end fed 1/2 wave matching system end feed

You can't argue with physics. Well you can, but you will always lose.

Link doesn't work.


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[K7MEM]

Link doesn't work.

Maybe he fixed it because it works fine for me.

Martin - K7MEM

 

[ka3jjz]

Works fine here on IE11 (at work)...Mike

 

[cmdrwill]

Palomar Engineering has lots of resources and very good UnUn's and isolators.

 

[SCPD]

If I read the original post correctly, he has the antenna mounted under his neighbor's deck. Did I read that wrong?