EFHW Grounding Compared
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- เผยแพร่เมื่อ 28 มิ.ย. 2017
- All of these were within the margin of error as far as signal strength is concerned however the issue I was dealing with was BCI, broadcast interference from a local AM station. Some of these systems worked better than others when it came to sensitivity to BCI. I don't pretend to know why. If you live in a high RF environment you can try one of these.
- วิทยาศาสตร์และเทคโนโลยี
Thanks for the work on the EFHW. 2db difference overall. Significant.
UTTERLY fantastic.
Thank you
I recently installed the myantenna 40M/80M/160M EFHW , mounted as an inverted V with the apex at 110'. Measuring with a MFJ clamp on RF current meter, 28ma. was measured at the antenna transformer, 50 ma. in the shack, with 10w Tx. There was no change when grounding the transformer to a ground rod, but now the SWR was closer to manufacturer specs. After installing the myantenna RF choke, mounted as shown here, there was no reading at the transformer or at the shack side of the transmission line. There was a slight reading on 160M.
Wonderful scientific research
Great work, brother !
Useful and interesting, thank-you.
Thank you for making this video and sharing it with all of us.
Can you please specify exactly which choke model number end fed antenna system you are using in number one?
Additionally can you please describe the 94 ft of wire and how it was run with number two?
Thanks for sharing 👍
Nice work.
This is a very helpful video for EFHW. Could you do a test and video like this for the End fed random wire antenna design or give us your guess about how the EFRW design should be configured with respect to counterpoise, choke, and grounding?
If you think about it, there is no such thing as an "end fed random wire". The feed point will never be at the end because there is a counterpoise. The feed point impedance will be determined by the frequency and placement of the feed in relation to the wire and the CP. The counterpoise can easily radiate more than the antenna if the wrong length is chosen. Technically you need a full radial field for proper operation otherwise much RF loss will occur in that CP system. EFRW's are not good antennas but of course you can always make contacts with them and if you're in a contest you'll always get 599.
Thank you for doing this Steve. Very helpful! 73//KK0DJ
Nice work Steve, tnx fer sharing......k6sdw
Was the 19" antenna at the SDR vertical, as shown in the video, or was it horizontal? Did you use both and average them or something? If you didn't, would it have made a difference?
The changes I made at the feed point wouldn't have much effect on the polarity of the transmitted signal and my antenna system did not change. I was very careful to NOT disturb the pickup antenna.
On your diagram for the "best" system...you show a choke on the coax. Can you recommend what manufacturer and model # of the choke ? (Ant = myantennas EFHW-8010)
8 or more turns of RG-8x or LMR-400 wrapped around a 240-31 mix ferrite torroid. Really you shouldn't need anything since it's grounded. I had trouble at that qth with strong BC qrm.
What kind of choke was it? Could it be home brewed? Thanks!
Just a common mode choke. Sure it can be home brewed.
great video but what drives me up the wall is that the antenna manufacturers tell you do install it different.
Oh really? What are they recommending? Actually #1 seems to be the most popular. I've also do a lot of these with the whole thing horizontal including the transformer. They all work.
Steve: Please tell me about the choke you used. Why did you add it ? What was special about it ? (i.e. chatacteristics, etc.) . Do you remember the Myantenna P/N ? Where you planning to used it across the bands ? I will be installing the same antenna this fall before the snow flies and need it get it right the first time. (Snow gets deep here.) Thanks for video and all the work behind it. Regards, a Newbee
I have since eliminated it. I was having trouble with local AM radio stations and the choke helped. I have since installed a high pass BC filter at the rig. I wouldn't bother with it if I were you. The direct ground does help virtually everything though. Nothing fancy, just a 8ft ground rod will do the trick. It also provides lightning protection. 73
Your EFHW video's have been extremely valuable and educational.. thanks for sharing your test results/experiences. I have been looking at MyAntenna products and was trying to determine if the choke was worth purchasing/implementing. Your experience clearly shows that it is worth the investment!! Question .. does it make a significant difference if the choke is located at the antenna versus the transceiver ? Thanks, Jeff WA4LLL
In my humble opinion it is better to have the choke at the transformer but if you do, you will need either a ground rod connected to the ground terminal on the box or a counterpoise wire at least 12 feet long or so. Putting the choke at the shack will keep RF off the rig in cases where the coax shield is picking up RF from the antenna but it won't isolate the coax shield from your transformer. I would put it on the antenna end and if that doesn't work try another one at the rig. The myantenna's choke is a bit expensive but does seem to work well.
Steve Ellington do you recommend another brand of choke that isn't this expensive?
Over the past year of experimenting with these things I can honestly say that I don't know. There are too many variables to make a blanket statement, yes or no. If you are having problems with RFI in the shack then the choke would be a good addition and typically it works best on the "shack end" of the coax. If you use a choke at the transformer then you loose the counterpoise effect of the coax shield and will need to provide another ground or counterpoise. This might be a good idea if the coax happens to run near a noise source... Even a choke at both ends might sometimes be of help. Right now I have no chokes anywhere but I do have a very good ground at the transformer. The Myantenna choke does seem to be a good choice.
Wouldn’t chicken wire rust and deteriorate fairly quickly? Did you just lay it on the grass and use lawn staples?
Yes. Chicken wire is short lived. I prefer using horse fence, welded mesh. Just use cheap tent stakes to hold it down although it can get rather frisky.
Steve Ellington do you just mow over it ? I’d love to see a vid of your yard. 73 from ky
-88 dB of what? Compared to what reference?
Compared to the reading with no signal. This comes built in to HDSDR
Way too close to do such a test.
Your rx needs to be many wavelengths away.
Ch0ke ✔