Posted: 2/6/2017 6:35:32 PM EDT
| I put up a new 10 meter 18ft. vertical this weekend , got it on a 40 ft pole so the tip is at 58 ft. So i was going thru the bands to see what it will work on and made 4 contacts in Europe in about 15 min. on 15 meters , it tunes up good on 10 ,15 , 17, meters can tune 20 but its deaf as a post on 20. Well i tried the cb band and damn i havent heard skip running like that in 20 years and it lasted till 9:00 sat. night before it died. it was nuts so many people on there , like i said first time in 20 years since i heard it like that. |
| A common mistake among many hams is to assume that if an antenna tunes with a tuner, they are good to go. It was partially fueled by some manufacturers selling tuners capable of tuning just about anything. This is so wrong. A good antenna should not have SWR greater than 2:1 within a band it was designed for. Tuning a 10m antenna on a 20m band cuts your antenna efficiency by 90+%, meaning that the antenna will only radiate several watts when you feed 100 Watts into it. |
|
Quoted:
Yep, 20 meters was the only band I needed a tuner on , 15,17,10 meters were all below 1.4 swr. Quoted:
Yep, 20 meters was the only band I needed a tuner on , 15,17,10 meters were all below 1.4 swr. Leads me to believe that your have quite a bit of loss in your feedline or somewhere. Quoted:
Tuning a 10m antenna on a 20m band cuts your antenna efficiency by 90+%, meaning that the antenna will only radiate several watts when you feed 100 Watts into it. Hardly. He has a 5/8 wave antenna for 10 meters. It'll be a little over 1/4 wave on 20 meters, and as long as you have a reasonable tuner and system loss, should work fine on 20 provided the support structure makes a sufficient counterpoise. Adding some 20m resonant ground radials below the antenna would help a lot. I made a lot of contacts on 20 from a CB 5/8 wave vertical after I got my first HF radio. The exception is that if you have a shunt fed type antenna, it won't work for crap off frequency. I'm not familiar with every type of CB/10m antenna. |
| Its the old Anton A-99 18ft. cb antenna,i dont have radials and not sure if helped or hurt but my pole is right net to my fence not chain link but the 4inch square wire fence and i wrapped bare solid copper wire around the pole several times and wove the other end all thru the fence , the fence encircles about half a acre. Did notice on 20 meters running 100watts it only showed about 20 watts going out. I could adjust it to work better on 20 meters but i adjusted it more for 15 and 17 meters , i have a good 20 meter antenna. |
|
Quoted:
Its the old Anton A-99 18ft. cb antenna,i dont have radials and not sure if helped or hurt but my pole is right net to my fence not chain link but the 4inch square wire fence and i wrapped bare solid copper wire around the pole several times and wove the other end all thru the fence , the fence encircles about half a acre. Did notice on 20 meters running 100watts it only showed about 20 watts going out. I could adjust it to work better on 20 meters but i adjusted it more for 15 and 17 meters , i have a good 20 meter antenna. 1 - you need ground radials 2 - get rid of that bare copper wire, it's not doing anything for you other than promoting corrosion You said "pole" in the OP, is this a wood pole? Or metal mast? ETA: Found how the A99 is made. Ugh. http://www.radiomanual.info/schemi/ACC_antenna/Solarcon_A-99_review.pdf It's basically an end-fed (misnomer) 1/2 wave with a very lossy matching system. From the height I had presumed it to be the traditional 5/8 wave type antenna, but it is not and will not work well in this application. |
I didnt know if attaching it to the fence would make much of a difference , i have used the fence several times as a counter poise for 160 meters, i will run a 123 ft. piece of wire in the brush above the fence about 8 ft. and it makes a damn good NVIS antenna on 160 and 80 meters when i shorten it too 58 ft. My emergency antenna after Hurricanes. LOL Thank you for your advise  , i know a little about antennas from making a bunch of them but am no way an expert thats why i like to post what im doing on here.
|
|
Quoted:
Yeah the copper isn't going to do anything good for you, versus the mast itself. Bare copper in contact with other metals generally leads to galvanic corrosion of the other metal. It's even worse if the pole is zinc galvanized / plated. Copper contacting the pole will strip the zinc away. Use thin stainless foil where copper contacts zinc coated metals, to separate the two at the point of contact (grounding connection etc.) |