KE0GXN
Member
Not into any digital modes as of right now. Having to much fun on phone/SSB.
But I'll keep that in mind, thanks!
G5RV dipoles ?..
- Thread starter KD8NIV
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Not into any digital modes as of right now. Having to much fun on phone/SSB.
But I'll keep that in mind, thanks!
KE0GXN
Member
Pulled the trigger on a ZS6BKW today. It is made by W8AMZ.
It is made by W8AMZ.
I too purchased the W8AMZ ZS6BKW about 6 months ago now and its a great antenna. Have worked 150 countries barefoot with that puppy in that time span. I have it up at 45' in the center and 20' on the ends. I think you will be very happy with it.
Mike
Mike
KE0GXN
Member
Looking forward to it!
For what it is worth, been using the MFJ full-size G5RV, up about 40', barefoot and by causally operating (I am relatively young, with a young family and a full-time job) I technically got WAS already (just can't get everybody to confirm) and 33 countries so far in about 4 months of operating.
In my opinion, as long as you do a good installation with attention to detail and with some operating persistence you can get out and be heard almost anywhere.
Looking forward to what I can log with the ZS6BKW though!
KE0GXN
Member
Do I need to keep my 6" 10 turn coax RF choke/air wound balun for my ZS6BKW? Instructions that came with it did not say one way or another. Contacted and asked the seller and he stated, "usually, no."
MFJ instructed/recommended for their full-size G5RV a 4"-6" 8 to 10 turn choke/air wound balun...I went with the max.
MFJ instructed/recommended for their full-size G5RV a 4"-6" 8 to 10 turn choke/air wound balun...I went with the max.
KD8NIV
Member
I was always told to use a choke/balun on a antenna, well in my situation anyways, because my neighbors are all close to me, even tho I don't run a amp, I still have my 6" coax choke inline.....still in the learning stages here myself...
KE0GXN
Member
Yeah, I ended up keeping what I had with the MFJ antenna. I asked elsewhere and was given the same advice you stated.
Same here John, learning everyday as I go.
Thanks for responding and 73!
Same here John, learning everyday as I go.
Thanks for responding and 73!
prcguy
Member
A ZS6BKW needs a good choke balun at the junction of the ladder line and coax, otherwise the coax will become part of the antenna on most bands. An air wound coax balun is a very poor choke and you might look for one with coax wrapped around a ferrite core, which is very effective.
I've tested the long tubular types with large ferrite beads slipped over the coax and they are way better than coiled coax but still not that good. You can make a very effective choke balun with a $10 FT-240-31 ferrite core and wrap about 10 turns of coax around it. You will probably see a reduction in your noise floor by adding an actual RF choke in place of your air wound coax.
prcguy
I've tested the long tubular types with large ferrite beads slipped over the coax and they are way better than coiled coax but still not that good. You can make a very effective choke balun with a $10 FT-240-31 ferrite core and wrap about 10 turns of coax around it. You will probably see a reduction in your noise floor by adding an actual RF choke in place of your air wound coax.
prcguy
KE0GXN
Member
KD8NIV
Member
Hello guys, still running the G5RV, in this same location up on the mountain side, hung between 2 tree's, , and has done real well in most directions.....
When I moved this dipole up there I thought I had enough coax to reach it but I didn't....so, I ended up using a 120' of LMR 400UF coax, and used a barrel connector and added about 50' of RG 213 coax I had here, and it goes into the shack....tuner tunes it for 10-80m bands.....
Problem I'm having is some RFI inside the shack, seems to be affecting my computer some, as you talk on the radio, the computer seems to freeze up or something......still just running a 100 watt radio, no amp...
What do you all suggest to get rid of the RFI in the shack ?....
When I moved this dipole up there I thought I had enough coax to reach it but I didn't....so, I ended up using a 120' of LMR 400UF coax, and used a barrel connector and added about 50' of RG 213 coax I had here, and it goes into the shack....tuner tunes it for 10-80m bands.....
Problem I'm having is some RFI inside the shack, seems to be affecting my computer some, as you talk on the radio, the computer seems to freeze up or something......still just running a 100 watt radio, no amp...
What do you all suggest to get rid of the RFI in the shack ?....
prcguy
Member
Do you have a choke balun at the junction of the ladder line and coax? If not read post 128 above to make a very effective one for about $10. A G5RV or ZS6BKW is a balanced antenna and if you simply connect coax to the ladder line or twinlead, common mode currents will flow on the outside of the coax and it will radiate.
There are some really marginal common mode chokes on the market and even if you have one now it may not have enough resistance adequately isolate the balanced antenna from the coax.
prcguy
There are some really marginal common mode chokes on the market and even if you have one now it may not have enough resistance adequately isolate the balanced antenna from the coax.
prcguy
KD8NIV
Member
No, didn't use a Balun.....
Just made a coax choke 6" across ...
Just made a coax choke 6" across ...
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prcguy
Member
At best it won't do much and more than likely probably nothing. You can sometimes find commercial units that will do an adequate job on Ebay in the $20 range used. These tubular versions that have a bunch of ferrite beads over coax will give about 20dB of common mode rejection at best and it will probably fix your problem. Here is one example but at a new price: LINE ISOLATOR - CHOKE AMATEUR RADIO BALUN by SPI-RO MFG.!!!!NEW | eBay
You can build your own that will do a much better job and handle full legal limit for about $10, just buy an FT-240-31 ferrite core from Amidon Associates and wrap 10 turns of RG-8X or RG-142 coax around it. Here is a commercial version in a box for $83 and you don't really need the box. 1:1 Feedline Isolation / Common Mode Choke by Balun Designs 1.5-54 MHz, 5kW.
This type of choke where you wrap 10 turns of coax through a ferrite toroid can give you over 30dB of common mode rejection and for only the cost of the core and you can probably wrap your existing feed line through it.
prcguy
You can build your own that will do a much better job and handle full legal limit for about $10, just buy an FT-240-31 ferrite core from Amidon Associates and wrap 10 turns of RG-8X or RG-142 coax around it. Here is a commercial version in a box for $83 and you don't really need the box. 1:1 Feedline Isolation / Common Mode Choke by Balun Designs 1.5-54 MHz, 5kW.
This type of choke where you wrap 10 turns of coax through a ferrite toroid can give you over 30dB of common mode rejection and for only the cost of the core and you can probably wrap your existing feed line through it.
prcguy
Hey KD9NIV
.
I am going to suggest something a little unorthodox;, it has work'd for me many times in the field- usually (but not always!) as a choke to cancel the common mode issue you seem to be describing. Its simple and it is cheap- get a few dollars worth of steel wool (yes, you read that right) and wrap several feet of it around your coax-- length, spacing, position on the line, number of 'chokes' to be determined experimentally .Is it worth a try?...hmmm.... I give it 'thumbs up'--- we have a package of it that always goes out on projects--
.
The good thing is; if it doesn't stop RF from creeping back into your 'shack' - it works great to keep mice from crawling thru the feed line holes in the side of your government radio-station-slash-residence-hut (shades of one of the last successful use of this steel wool.... )
.
Good luck; it is a problem easy beaten...!
.
..........................CF
.
I am going to suggest something a little unorthodox;, it has work'd for me many times in the field- usually (but not always!) as a choke to cancel the common mode issue you seem to be describing. Its simple and it is cheap- get a few dollars worth of steel wool (yes, you read that right) and wrap several feet of it around your coax-- length, spacing, position on the line, number of 'chokes' to be determined experimentally .Is it worth a try?...hmmm.... I give it 'thumbs up'--- we have a package of it that always goes out on projects--
.
The good thing is; if it doesn't stop RF from creeping back into your 'shack' - it works great to keep mice from crawling thru the feed line holes in the side of your government radio-station-slash-residence-hut (shades of one of the last successful use of this steel wool....
).
Good luck; it is a problem easy beaten...!
.
..........................CF
KD8NIV
Member
Well maybe I should have posted this instead, I still have some RFI in the shack, planning on raising my G5RV up higher in a few weeks and looking for the right move to make as I do this....right now I have roughly 170' of coax on it, and after I raise the dipole up, and make a coax choke using the LMR coax, this will be alot of weight on the wire, bad thing is the ladderline and coax will all be up in the air, and nothing to lay the coax against, the wind will blow it all around....
Question is, would I gain anything if I went to ladder line from the dipole all the way down to the outer wall of the shack, and come inside with a shorter piece of coax ?.....
Question is, would I gain anything if I went to ladder line from the dipole all the way down to the outer wall of the shack, and come inside with a shorter piece of coax ?.....
prcguy
Member
Coiling up the coax to make a choke is a waste of time and will not fix your RFI problem, you need an effective ferrite based choke. Another thing is the G5RV was designed as a 20m antenna and will have a reasonable match there, everywhere else its just a random length dipole and the VSWR is all over the map.
You also have a very long run of coax but its fairly low loss, even so it will have additional loss beyond what is advertised because its being used under very high VSWR conditions with a G5RV. Running ladder line all the way from the antenna to the shack using a very short run of low loss coax from a tuner to a 1:1 balun feeding the ladder line will reduce the feed line loss further, but you will no longer have a G5RV and you might as well run a classic 135ft dipole fed with ladder line at that point.
Better yet modify your G5RV into a ZS6BKW and you will gain some performance in the 40 through 10m bands and will also have a much better match to coax, reducing some feed line loss from the G5RV with the lousy match.
Are you raising the antenna to get better performance? What bands do you favor? In my opinion a good height for a G5RV or any multiland dipole is about 1/4 wavelength high on 40m or about 33ft. This will take the best advantage of NVIS on the 80 through 40m bands for local or regional comms and it puts the antenna about 1/2 wavelength high on 20m and a full wavelength on 10m for a lower take off angle for better DX.
Do I need to send you a ferrite 1:1 choke and a length of ladder line to modify your G5RV into a ZS6BKW? Don't make me do it.....
prcguy
You also have a very long run of coax but its fairly low loss, even so it will have additional loss beyond what is advertised because its being used under very high VSWR conditions with a G5RV. Running ladder line all the way from the antenna to the shack using a very short run of low loss coax from a tuner to a 1:1 balun feeding the ladder line will reduce the feed line loss further, but you will no longer have a G5RV and you might as well run a classic 135ft dipole fed with ladder line at that point.
Better yet modify your G5RV into a ZS6BKW and you will gain some performance in the 40 through 10m bands and will also have a much better match to coax, reducing some feed line loss from the G5RV with the lousy match.
Are you raising the antenna to get better performance? What bands do you favor? In my opinion a good height for a G5RV or any multiland dipole is about 1/4 wavelength high on 40m or about 33ft. This will take the best advantage of NVIS on the 80 through 40m bands for local or regional comms and it puts the antenna about 1/2 wavelength high on 20m and a full wavelength on 10m for a lower take off angle for better DX.
Do I need to send you a ferrite 1:1 choke and a length of ladder line to modify your G5RV into a ZS6BKW? Don't make me do it.....
prcguy
KD8NIV
Member
I no the G5RV isn't the best dipole out there, and having power lines in my area has been a headache by it's self, even tho I moved it, I still have headaches where it is, that is out of my control.......just trying to make this one work.......
The 120' of coax I have on it, just does drop the coax down in the edge of my yard, and came on into the shack with the other stuff, lot longer run of coax than I wanted to use...
Planning on raising the dipole to see if it helps like to think it will......I like to work DX on 20m, and talk on the 40m and 80m bands, mostly just rag chew on those bands.......na, you don't need to send me that stuff...
The 120' of coax I have on it, just does drop the coax down in the edge of my yard, and came on into the shack with the other stuff, lot longer run of coax than I wanted to use...
Planning on raising the dipole to see if it helps like to think it will......I like to work DX on 20m, and talk on the 40m and 80m bands, mostly just rag chew on those bands.......na, you don't need to send me that stuff...
I'm going to throw a paradigm switch into this dipole topic- have you considered using a vertical? These antennas take up much less room, they are far more efficient than low height horizontals, they are physically stronger (if constructed well) among other reasons in their favor. There are others- like lightning issues if ground mounted. The vertical's low angle of radiation makes them superior to any low horizontals for DX, plus depending on the method of feeding them, the tuning circuits can at ground level-- no climbing up stuff, or lowering antenna wire; they can be easier to keep away from powerlines because of their smaller 'footprint,'..... Verticals can be simple to construct, tune and maintain...dare I add, even a bit of fun and educational?.. and they don't have to be full size-- I have used a 20 foot tall, base load vertical on 160 and talked easy over 1000 miles (at night and in the winter, 800 Watts- but hey, that's 160)- unthinkable on a low horizontal wire.
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With years of RF experience, I have used many an antenna. Unless it was to throw something up into the trees (for which I prefer a terminated long wire- an entirely different topic,) I'd prefer a vertical any time. You mention powerline noise- you may find a reduction by going to vertical polarization. Also controlling your common mode RFI issues may be easier. I understand a lot of hams are really pleased with their G5RV's and other horizontal antennas, but I am not one of them.
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Food for thought?
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...................................CF
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With years of RF experience, I have used many an antenna. Unless it was to throw something up into the trees (for which I prefer a terminated long wire- an entirely different topic,) I'd prefer a vertical any time. You mention powerline noise- you may find a reduction by going to vertical polarization. Also controlling your common mode RFI issues may be easier. I understand a lot of hams are really pleased with their G5RV's and other horizontal antennas, but I am not one of them.
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Food for thought?
.
...................................CF
Not if you put in the radial system required for best performance. Either you have elevated resonant radials so your friends can trip on them or you bury 24 or so radials which is a lot of work and may require tearing up the back yard to lay them down unless you have a grass lawn and good soil.
IF you have space and time to put up a good radial system the vertical part can be efficiently shortened with a capacitance hat, but the radials can't be. And then there's the guy wires.
prcguy
Member
I'm with Ed on this one, I've done countless comparisons of verticals next to very low dipoles and in most cases the low dipole works much better for DX than the vertical, unless you have a significant ground system under the vertical. Some of the verticals I've compared are the GAP Titan, Cushcraft R7, MA5, Hy-Gain 14AVQ, Butternut HF6V and some others I forget at the moment.
One test that sticks in my tiny brain is when I was in a coast to coast 40m evening net and had a G5RV with the apex around 30ft and the ends low at about 6ft off the ground. I switched between that and a 33ft vertical wire hanging from a 33ft fiberglass mast over four 20ft long ground radials laying on the ground, and this antenna had a good match on 40m without a tuner. I fully expected the full size 1/4 wave 40m vertical to outperform the low G5RV cloud burner for the DX stations and from my So Cal location people in the mid and eastern states said the G5RV was putting out a noticeably better signal.
The same results have followed me over countless vertical vs horizontal comparisons except for a few and one of those was a DX Engineering 43ft vertical over 30 something 33ft long radials (1,000ft of wire) laying in a very wet marsh. This vertical with an SGC auto tuner does outperform a ZS6BKW dipole at 30ft high on the same property fed with the same radio on 160, 60, 40 and 20m, but the dipole works better everywhere else. If I replace the SGC auto tuner with the stock 4:1 balun that came with the vertical, the horizontal ZS6BKW dipole kicks DX butt over the vertical on all bands.
The Butternut HF6V was mounted on a 100ft X 100ft bonded copper sheet metal roof and it worked very well, but the horizontal I compared with was a double size G5RV at 204ft long mounted about 20ft off the ground and it had lots of nulls and gain lobes on 40 through 10m where it was hard to do an honest comparison. Most of the time the Butternut vertical worked better but sometimes not. This station was in Hawaii, so pretty much everything is DX from there.
prcguy
One test that sticks in my tiny brain is when I was in a coast to coast 40m evening net and had a G5RV with the apex around 30ft and the ends low at about 6ft off the ground. I switched between that and a 33ft vertical wire hanging from a 33ft fiberglass mast over four 20ft long ground radials laying on the ground, and this antenna had a good match on 40m without a tuner. I fully expected the full size 1/4 wave 40m vertical to outperform the low G5RV cloud burner for the DX stations and from my So Cal location people in the mid and eastern states said the G5RV was putting out a noticeably better signal.
The same results have followed me over countless vertical vs horizontal comparisons except for a few and one of those was a DX Engineering 43ft vertical over 30 something 33ft long radials (1,000ft of wire) laying in a very wet marsh. This vertical with an SGC auto tuner does outperform a ZS6BKW dipole at 30ft high on the same property fed with the same radio on 160, 60, 40 and 20m, but the dipole works better everywhere else. If I replace the SGC auto tuner with the stock 4:1 balun that came with the vertical, the horizontal ZS6BKW dipole kicks DX butt over the vertical on all bands.
The Butternut HF6V was mounted on a 100ft X 100ft bonded copper sheet metal roof and it worked very well, but the horizontal I compared with was a double size G5RV at 204ft long mounted about 20ft off the ground and it had lots of nulls and gain lobes on 40 through 10m where it was hard to do an honest comparison. Most of the time the Butternut vertical worked better but sometimes not. This station was in Hawaii, so pretty much everything is DX from there.
prcguy
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