[Fourlanders] 6m antenna problem

[John Ackermann N8UR]

Sounds like the resonance you're seeing may be at the 3rd harmonic.  Possibly a failure in the match system (e.g., an open center or ground at the feed point)?  Hard to explain why that might happen on both antennas simultaneously, though. 

> On Jan 6, 2016, at 4:24 PM, Bob Lear <w4zst at windstream.net> wrote:
> 
> Need some advice about the 6m antennas.
> 
> We put them up last Saturday, connected a radio and heard stations in Texas on both the omni's and beams along with the usual local beacons.  Nothing else was done then and we didn't pull the hard line into the shack until Monday this week.  I ran Kim's AIM UHF analyzer on them and things didn't look good.  First I thought it was a jumper or the PD, but after eliminating some stuff, it looked more like the problem was in the stackmatch relay box.  Today I took the analyzer out to the tower base and started checking the antennas themselves.
> 
> Still not looking very good, at least nothing like we've been used to in the past.
> 
> The omni's have a 4:1 + swr around the normal operating frequencies.  They seem to be most resonant at 155 MHz where they show 1:1
> 
> The beams look just alike when scanned separately and also show about 4:1.  The lowest swr on them is about 2:1 at 150 MHz
> 
> both above observances on the AIM and my MFJ 259 are consistent so it's not the devices.
> 
> The computer crashed outside apparently due to the cold and I"ve brought it back in and it's working OK.  I've scanned from here, with antennas separated (no stackmatch) and through the stackmatch. They just don't look good at all.  SWR staying much too high like 4:1 at operating frequencies and higher elsewhere.  The stacked pair showed 1:15 swr at 135 MHz
> 
> Could this be because of the cold weather.  It's probably only about 35 outside here right now.   I don't think I've ever used these instruments in such cold weather before.
> 
> BTW:  all the feedlines look good when TDR'd
> 
> Any ideas from the peanut gallery?
> 
> Thanks and if we get any warm weather I'll do this all over.
> 
> Bob
> 
> 
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