Ok guys. I bought 2 NIB bottom A99 sections from an electronics clearence place, there were no middle or top sections. So I decided to make my own middle & top section out of aluminum tubing. I had a broken Imax 2000 & removed all the chromed parts so I had parts to attach the middle & top aluminum sections. Going by the orginal length of the A99 middles & top section which are about 6' each I started with those lengths but the swr was high with the tuning rings in the middle. I found I needed to make my middle & top sections about 7' long each & adjusted the length till I got 1.1:1 on both channel 1 & 40 & flat on channel 20. My question is why are the lengths so much longer using aluminum as the middle & top section of my hy-brid A99 ? I'm thinking that because the OEM middle & top section were just skinny wire inside & now I'm using elements that are much wider in diameter that it's either changed the capacitance / inductance thus changing the overal length was needed. My other concern is, will the bottom section be strong enough to support my new aluminum middle & top sections ? They are about the same diameter as the OEM fiberglass A99 ones & likely don't weigh much different. I just don't want the bottom section to snap off in a wind storm. Any thoughts gang. ????
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A99 Hy-brid.
- Thread starter dxing.bruce
- Start date
I believe the OEM A99 may have a capacitor inside to make it electrically longer. I know Imax 2000 does.But I could be wrong.
If you look up A99 exposed, there's a guy who took an A99 apart & there is just a copper wire in the middle & top section. The bottom section contains a capacitor, two coils & then just wire to it's top.
There is some good reading here.
