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| 20m without balun |
On Saturday I picked up my
Balun Designs 1:1 balun and on Sunday I was able to do some on air tests. I wanted to see the difference between using the 1:1 balun and not using it. This post will deal with how my receive signal was affected with and without the Balun installed. I was able to take some screenshots from my Icom 7610 for this comparison. The first band I looked at was 20m, it was getting a bit late in the day so there was not a whole lot of action on the band. Even with the lack of signals I was able to see an interesting comparison. The span on the 7610 was set to 14.000 to
14.100 to cover the CW and digi section of the band. The local time was in around 22:37 and without Balun Designs 1:1 balun installed the section of 20m from 14.000 to 14.100 showed some what I called washout sections. I did notice around the 14.040 mark there is some RFI on the waterfall. When I moved the VFO over to that section the RFI was very faint. Also a very faint indication of RFI on the waterfall just past the
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| 20m with balun |
14.080 mark.
When the 1:1 balun was introduced the band cleaned up regarding the washed out sections. I was able to see digi signals, in the posted picture the digi signals are almost gone from the waterfall. There was some CW signals close to the noise floor that I was able to hear (not shown in the picture). I did notice the RFI what was in the waterfall without the balun installed is gone BUT after the balun was installed at 14.080 there was a stronger RFI signal and I could hear it very well when tuned to it. This RFI was not there all the time I would say it was on and off. Not sure what it is but that is not the purpose of this post.....save that for another post.
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| 20m RFI without balun |
With the 1:1 balun installed it seemed to clean up the band and bring out signals that were otherwise washed out.
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| 20m RFI with balun |
The next band I did was 30m and the span was 10.100 to 10.150 I found without the 1:1 balun installed the 30m band was washed out with just a hint of digi signals between 10.130-10.140. Once the balun was installed the band cleaned up and there was no longer a washout effect. The digi signals were much more significant and I also was able to see some CW signals on the waterfall. I did notice just
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| 30m without balun. |
to the right of the digi signals something on the waterfall. I was not really hearing any RFI when I tuned it in maybe it was packet I am not sure?
Because it was later in the evening 40m seemed to really shine when I preformed the comparison with and without the balun installed. The span on 40m was 7.000 to 7.100. Without the balun there was some CW signals as well as some digi signals that I noticed. I was pleased with what I saw until I placed the balun in the picture. This cleared up the band and I was able to see more CW signals and the digi section was much more pronounced. I also noticed according to the S-meter with the balun was in around S-4 and without just over S-5.
I am very pleased how the balun has improved the reception end of things.
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| 30m with balun |
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| 30m digi signal with something to the right? |
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| 40m without balun |
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| 40m with balun |
Comparing receive signals with and without 1:1 balun.
21 October 2019 | by 
HamRadioAuctions
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Wood love to include on of these baluns in my antenna.
You left no model numbers or part numbers.
BALUN designs only shows products for the uhf bands and higher .
I saw no HF BALUNS listed. The UHF baluns have a surface mounted network
also attached to them….not just a simple 1 :1 balun.
Without a balun received and radiated signals may be to/from the coax cable which on receive means that local interference from household appliances will be more of a problem. It shows up more on really high antennas with >100′ of coax. I think that I’ve verified this but it is pretty subtle and off-the-air signals are erratic.
Good evening John and thanks for stopping by and leaving a comment, I did include a link in the blog. It was in the first sentence that said “balun designs 1:1”, I am very sorry if it did not stand out please let me know if it is hard to locate andI can change the colour of the link that makes it easy to see? The model of the balun is 1115 with SO-239 connectors. If you have any other questions please email me at ve3wdm at hotmail.com……this is my former call as I have not changed the email address as of yet.
73 John and please do email me if you have any other questions.
Mike
VE9KK
Good evening Ken, I agree that the coax on an Endfed will pickup the surrounding RFI devices but it’s good to see how the 1:1 removes that RFI and leaves you with mostly radio signals. My Endfed is only 20 or so feet off the ground but the coax run is about 60 feet into the shack.
Ken thanks for the input.
73,
Mike
VE9KK
I didn’t realize a balun could make such a difference on receive. Where did you connect it in your setup?
Depending on whether or not this was a current balun, it would seem that the very heavy coax shield feedback of the end fed (as it performs as the ground) is dissipated to a real ground, when installed correctly, better so the signal is purer. Baluns are mandatory on EF antennas as are common mode chokes, often the same thing as found in a proper grounded current balun. Even adding a string of magnetic beads will help on most antenna feed lines, including the EF antenna.
Good evening David, I am using an Endfed antenna and with this type of antenna it uses the coax braid as a counter poise. I am assuming this also is picking up the extra noise you see on the 7610 display. Once the 1:1 balun is put on you can see the results. As to where I place it in my case it is at the radio as I need to have the coax to still act as a counterpoise. I have had dipole type antennas in the past (not an Endfed) and I added a 1:1 balun to remove any possible common mode current on the coax. In the case of a dipole I did not notice the receive affect I did when it was added to the Endfed antenna.
Thanks for taking the time to comment David.
73,
Mike
VE9KK
Good evening Bart, the Balun Designs balun 1115U is a current balun and yes I agree 100% that the coax has a very good shield feedback. I have never used an Endfed antenna before up to this point in time my antennas were the MFJ 1788 loop, Alpha Delta DX-CC and way back the Crushcraft A7. The Endfed antenna is used as it fits on the small foot print of property that I have and I don’t have to retune it al the time like with the MFJ loop antenna.
Thanks for the comment Bart,
73
Mike
VE9KK
Excellent real-life demonstration of theory, many thanks. 73
Very interesting and informative article.
Thank you very much.
73s
Interesting article, thanks for that. However, I am somewhat confused about placement of the ‘balun’. I am using a EFHW 40 mtr ant that has a “49-1 ratio transformer” on the end of the coax that connects to a 66ft ant wire. Is this equivalent to the same thing or should I have a 1:1 at the output of my 939y auto ant tuner where the coax feed line is connected? Thanks es 73
Good morning Walt and thanks for stopping by, thanks for the question Walt and yes like your Endfed I have a balun at the coax end that feeds the antenna wire, my antenna wire happens to be 34 feet. My Balun is a 9:1 and yours as you said is a 49:1. The 1:1 balun is placed at the transceiver end of the coax as in my case which is in most cases of Endfed antennas the coax shield is the counterpoise for the Endfed antenna. For this reason sometimes with Endfed antennas RF can get into the shack and cause issues. I use the 1:1 balun (or isolation balun as it is sometime called) to remedy this problem. So yes keep the 49:1 balun at the wire antenna end but if there is RF issues place a 1:1 balun at the other end of your coax. Now having said all the above because the coax shield acts like a counterpoise you may also be picking up some extra receive elements as well. You can see by the post how the !:1 cleaned up the receive signal as well. If you are going to make or purchase a 1:1 balun make sure you purchase one with a high quality toroid core properties.
73 and I hope I answered your question Walt?
Mike
VE9KK
Very nice to hear from you Elwood and thanks for the comment.
Mike
73
VE9KK
Good morning Shama and always nice to hear from India, thanks for taking the time to read the blog and have a great week.
73,
Mike
VE9KK