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HYGain AV680 Vertical

Jul 24th 2020, 12:13


Joined: May 14th 2019, 22:07
Total Topics: 0
Total Posts: 0
I have a HyGain AV680 Vertical antenna fed with LMR400 (50') connected to an Icom 7610. I'm getting high swr readings on all bands which indicates I have a short someplace.

I have a MFJ 269b meter and have disconnected the feed cable at the antenna and checked for shorts on the feed cable. Feed cable is good.

I put this antenna together myself and in the process discovered that the matching box had several un-soldered connections which I fixed.

What would be the best approach to checking the antenna for shorts and determining where the short might be. MFJ tech support was no help.

Any suggestions would be greatly appreciated. I also have a Buck master 7 band dipole that works great fed with LMR400 as well to the 7610, so I know it is not the radio or the feed me problems. I dont see any obvious construction problems.

Nov 25th 2020, 13:25


Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
High SWR readings on all bands does NOT necessarily indicate that you "have a short someplace." It only indicates that there is a mismatch to the 50 ohm transmission line.Unfortunately winter weather is fast approaching most of the USA, so you may have to wait until spring to take the antenna down for maintenance and repair. When you drop it down:
Go back to the assembly manual again and determine the proper connections to the matching coil that you"fixed" during assembly. Repair as required.
Next, in order to get a reasonable SWR across each frequency band you must CAREFULLY adjust the tuning settings. Do this in the exact order listed in the manual, because the tuning adjustmentsof different bands interact.
The antenna base must be at least 8 feety above ground during the tuning process! Your MFJ analyzer should be quite helpful during this part.

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