I bought three of these and have had one running on 1090 since I joined FA . You can see my stats for reference. Running indoors, in a NW facing windows about 25’ up on a RTL 820T2 dongle and Intel Compute Stick on Win10 Pro
It is not necessary to take it apart or unscrew the radials for trimming. However, I took one completely apart and got the dimensions so you don’t have to:
Radiator is pressed in to the hardline center. DO NOT ATTEMPT TO TWIST AND REMOVE IT. Trim it in place. It protrudes 81mm from the center conductor (measured with cover off) Remove the black plastic bootie and trim accordingly from the tip. (13mm for a 68mm adjusted length)
Ground Radials are 84mm long and threaded into the aluminum base ring, measured observing the three to 4 threads left exposed. Remove the black plastic bootie and trim accordingly from the tip. (16mm for a 68mm adjusted length)
If you insist on taking it apart to see the guts, after the three radials are unscrewed and removed, the assembly slides out of the cover. It is a bit fiddly to get the threads all lined up when putting it back together. Remember this is aluminum, so be gentle.
Antenna works somewhat better than a homebrew groundplane I made, much better than the colinear, or the Franklin I made. Go figure. I make a lot of antennas for ham radio on all bands. These are fun because the elements are small. Lots of room to experiment.
As for the cost of the antenna, it is commercial quality, though I don’t think it was designed for outdoor use, seeing that it uses a BNC, but it’s perfectly fine outdoors if you use some electrical grease or tape it up nicely.
The seller has it for “Make Offer” so I paid 8 bucks each plus shipping. It would cost me more than that in gas, time and effort to create something that is not as well made.
Most folks don’t have the machine shop to turn out an aluminum ring with threaded holes at the perfect angles, plus the threaded radials, a threaded center, the PVC hood and the tips, plus a piece of hardline with BNC connector for $12
I’m also using one of these antennas, not trimmed, since it is for 800 MHz, on a low power HDTV transmitter on ch 25.3 (835MHz) Works great.
The other one is on one of my Icom PCR-1000 receivers, listening to public service stuff.
Here’s some background info on the original design intent for this antenna mobileinfo.com/Wireless_Netw … ardis_.htm