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SWR problems on a base antenna


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Posted

So I got a Nagoya NMO-200c 5.5dbi, RB-50 magnet mount, and GPK-01 base ground plane kit for my btech 50x1. It sounded great and signals where coming in clear on the magnet mount and when I finally got a 20ft mast up I put it on the GPK-01 kit. It sounded great the first week but I had to keep taking it down and putting it on my magnet mount until my midland 3db ghost antenna arrived. A few days ago as the left overs of that hurricane moved thru the area I started not being able to hear repeaters that where coming in clear before. I figured it was just the storm because I was listening into a local ARES ham net and they where talking about reception problems related to the storm as well. Then yesterday I was attempting to contact my brother over a repeater and I couldn't hear anything where we normally have clear comms. I hit the monitor button and still couldn't hear anything. Then someone else came on the repeater and I heard them clearly but weak and said they could hear my brother and me fine so it must be on my end. My nanoVNA just arrived today with my ghost antenna so I figured I would throw it on to see what the swr was and it is showing an swr of 1:2 on 462.540, it drops to 1:1.02 on 464.520 and starts going back up to 1:2.03 on 467.760. The radio says it recommends and swr of no higher than 1.5. Did I possibly damage my receiver? I didn't tape up the coax connections because it's only set up temporary could water ingress cause this? The antenna is what btech recommends and it says it's rated at v.s.w.r.: <1.5. The ground plane radials screw straight in and are at 90 degrees to the antenna, should they be bent down to 45 degrees?

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Posted

One thing is clear, you can't damage receiver with high SWR. The high SWR, the mismatch, may (or may not) damage transmitter. And 1:2 is not that high. SO-239 connector is not water-proof. I would take everything apart, dried it out and tried again.

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Posted

I got the Nagoya 200-C as well to put up as a base antenna using a ground plane kit.  I could not ever get a good signal out or an SWR below 2.0 using the ground plane attached to a pole.  I grounded the kit to the pole and the antenna to an arrestor.  Still would not come down.  When tonight, I put it back onto the NMO mag mount and stuck it on a piece of metal outdoor metal canopy, it starting chatting up a storm and the SWR was 1.01 and in middle of band 1.14.  Anyone know how to get this to work up on a mast?  I got it to work on a secondary location on my property.  I might just get a 3x3 sheet of metal and mount up and use it that way.  Not what I want to do but seems to be working that way.  

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