I wonder if we might be going at this the wrong way. We're spending $500 or $1,000 for a difficult-to-find commercially made antenna that might be a compromise for the frequency we're on.
What if we just make our own antenna? Is it that hard to do? There's a lot of 1/2 inch copper water pipe available. If you don't want to bend it, you could use 90 degree elbow fittings to form the loops. Has anyone done this? For my garage repeater, I would love to have a single folded dipole that I could bolt to the side of Rohn 25. One dipole for 220 MHz and one for 450 MHz. If I buy a commercial 4 bay, I have to mount the mast next to the Rohn anyway. The mast just adds weight and wind load. With my health deteriorating, I think that I can lower and raise the tower one more time, so the antennae that I install must be robust and last the rest of my life without maintenance. I was going to use a Tram 1481 to replace the Comet GP-9 on the 147 MHz repeater. (The top two sections of the GP-9 are leaning over 10-15 degrees. I know I tightened them before raising the tower.) But, after hearing the discussions about lightning damage, I want a DC ground design with no capacitors or coils. The 147 MHz antenna should be shorter than the GP-9, because it whips around in the wind on top of the tower. I'm willing to sacrifice gain for reliability. For 147 MHz, I looked at the Tessco DB201 G, but it's a lot of bucks and may not be resonant on my frequency. I thought about making a J-Pole out of copper pipe, but the transition from a balanced antenna to an un-balanced feedline is an issue. Any ideas for something for 147 MHz that's short, grounded, less-expensive, and rugged? Mike - AA8K
