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Antennas made for QRO, QRP and portable use
Here are some common questions and my answers. Feel free to ask any questions you have.
73,
Frank - KL7IPV
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Questions:
1. Do you sell completed (and/or kit) antennas? What is the price and lead time?
I don't sell kits but I do sell completed antennas. It is just a hobby thing and I have to buy materials to make one. I buy the coils from MFJ. The lead time depends on the ordering time from MFJ. Almost everything else is bought locally. The antenna whips are ordered on eBay.
2. May I also have some info on making my own?
Here is the long answer to this question. The main reason I started building my antennas was due to the costs that others charge. Having to pay $300 for an simple antenna is not something I wanted to do. I didn't think others wanted to either. So I built these. There is no "magic" to them. Here is how.
The antenna is nothing flashy but it works. Everything is "off the shelf" stuff. I use 2" black PVC for the body. I use MFJ inductor coils that have 102 turns of 14 Ga. wire. I use "wander leads" with an alligator clip to "rough" tune it with the lead first and then fine tune with a tuner. I buy the "hardware" from McFadden-Dale Hardware and online at eBay. I run 100 watts from my IC-706s and thru a tuner in the truck and the house and it works well. I use a LDG autotuner in the truck and MFJs' manual tuners with a Swan 100MXA in the garage and with a IC-706 MkIIG in the house. No problems with them either.
To put them on the PVC tube you have to use a Dremel or a similar tool to make 4 grooves in the PVC that the coil will slide over otherwise the coil wont fit. I glue it in place after I slide it over the PVC. I use a two foot piece of PVC only because it looked right and is available already cut to that length. I use 3/8"X24 threaded rod cut to about 9 inches for the bottom. You can make it shorter if you want. I use a PL-259 adapter on the rod to connect the coax to.
I looked up the coil in my paper 2009 MFJ catalog. On page 72 you will find the coil. 2 1/2" X 10", # 404-0008. I could not find it in the new online catalog. I also looked for the adapters that can be used to fasten my antenna or any other on a ladder; it is in the MFJ catalog as well on page 56 under "Mirror/Rack/Pipe Mounts".
MFJ Enterprises
I use 14Ga or 12Ga wire internally and then a 3/8"X24X1" screw on the top to a 3/8" coupler. I pin the coupler so it wont come loose in use. I use a 3/8" soldering eyes with flat washers and 3/8" star lock washers internally to hold it all together. I also use "jam nuts" inside to lock it together and "Locktite" to hold it. A "jam nut" outside against the bottom of the tube holds it all tight from the outside. Here is the seller I get the antenna whips and other adapters from:
Sauder Electronics
I use a 4' whip on the top but if you use it fixed it will work well with a 102" CB whip too. If you look at the pictures on the site you will see the material laid out with the white PVC. The only change was the PVC due to the sun affects on the white stuff. I found the black PVC resists weakening due to the exposure to the sun and the elements. I had a white one on my truck ONLY to test it and when I took it off last April, I tapped it against the concrete driveway and it shattered. THAT took care of me using white PVC. I use black PVC exclusively now!
3. What is the VSWR of the antenna vs. frequency when the wander lead is at the bottom (i.e. for tuner use)? The chart on your web site gives it vs. optimal position. My radio's built in tuner will only do 3:1 max... I assume I'll need an external tuner with expanded range, but I need to know what range is minimum for the tuner to operate over.
The chart I show is for guidance only. They do tune well and you can see how well on the chart. Each antenna is tested again to be sure it tunes like the others I have made. I use a MFJ-259 analyzer to do that. If you use the chart I enclosed with the antenna, you can "coarse tune" the antenna with the wander lead and then the radio can "fine tune" internally. I list the frequencies that fall UNDER 3:1 using the wander lead just so you'll know. There will be some times that the numbers I show WONT show for you depending on the surroundings and where you mount it. But if you use the chart, it will tell you close enough where to look with the lead to find the lower SWR to start with.
4. Was it designed for 100 watt operation?
I do use 100 watts from a IC-706 MkII, IC-706 MkIIG and a Swan 100MXA. The wiring and coil stock are heavy enough to take it. The coil stock in the air also helps to dissipate any heat generated.
5. Does it require ground radials?
Yes and no. I test all mine with NO radials. But any shortened vertical antenna is a compromise. Vertical antennas do better if they have a good ground counterpoise or radials. Mine is no different. Radials WILL help. Just having a ground on the adapter connector will help, I have seen that happen when the antenna was used in the 2008 field day setup by the Las Vegas Amateur Radio Club. I can send you a picture of that one.
At any time after you buy or build your own antenna, I will ALWAYS be happy to help you or answer questions to make it work better. Like I said, this is a hobby I first started in 1953 and licensed since 1966 and I enjoy it. If I can help others enjoy it as well, that makes it even more fun!
Don't hesitate to ask me questions. I hope I have answered most of them for you.
73,
Frank
KL7IPV
Las Vegas, NV.
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