Exteneral antenna added, stats dropped c50%?

Morning gents,

So, following my external antenna and coax flooding in the rains over Christmas here, I’ve been running with a small “spider” ant in the center of the attic, plus a HabAmp.
Stats were pretty good, covering 90% of my expected range based on that range website who’s name eludes me at the moment.

Average range was c220 miles, all lookiong rather good.

Gain was set to 38.6 or so in Mut, Peak was c-2.0.

Got my antenna put on the roof last night, c20:00.

N type - F-type connector, to c7’ Wf100.
Whole connector assembly covered in self amalgamating tape.
In line-sat-amp-in-tube removed altogether, so have a straight run from the ant to the habAmp.

Looking at the SNR, I was showing reduced noise, and really low peaks, so I cranked gain up to the oft-successful 44.5…

Seems to have improved things a bit, but still nearly 50% of what I had before.

My range “compass” and the plots on the maps certainly seem to cover more directions, so a) this suggests the ant is doing what I wanted (mounted above the roof line, so has better 360 view), and b) these results are what I expected in that regard, so seems the ant is connected successfully?


  1. Shall I just keep increasing the gain, or does the current performance suggest an issue - aside from the gain being cranked down from before?
  2. Is there a logical requirement to increase gain if you increase the size of the antenna, more gain to “drive” it or something?

*EDIT - if there was an issue with the an connection, and it was just using the coax etc as an ant, I’d expect:

a) No increase in “diection” coverage
b) stats to be worse than this

So hopefully it isnt that? (It’s taken me weeks to get this pig ant on the roof! :wink: )


Looking at the SNR and the ADSB Message rate, the complete lack of any signals “>-3db” leads me to believe there’s some way to go to increase the gain without “clipping”, so hopefully pushing the gain back up again should sort this?


*EDIT - tracks with single message looks rather high? /edit

My 7-day average confirms things have got worse…


Only question now is why and what to do about it?

Gah… :frowning:

Bit of work to do then…


Did you test external antenna performance (ideally in the loft just inside the hatch teamed with your new coax/connector set up) while you had it off the roof ?
To conduct small “sea trials” before committing to installing externally.

Er, no…

That said, before Christmas when it got flooded - I had that same external antenna in the same place, but with the old RG6 cable, inline amp and power inserter, rather than the Wf100 and HabAmp I have now.

So, although the current, external ant hasnt been tested with the new gear (wf100, HabAmb) it has been tested in the same location.

The main thing I’m looking for is the more 360 degree line of site (rather than inside the atic with the end walls etc), so it may not be massively different range (i’m already covering most of what I should be able to).

Either way, it didnt perform worse than my spider ant, which is actually my original ant I built myself in the begining.

Is there some logic that suggests a bigger ant would require a bigger gain, or is something looking not quite right?

I am thinking bigger means a collinear design which should give more gain than spider but in a different polar receive pattern.

Increase the gain. 48-49 or max

Thanks guys - pushed gain back to MAX.

Been running about 10 mins, ADSB Messages seem to be picking back up.

Will keep it running at max for a while, then see how the stats look…

Morning all,

Just to put this thread to bed…

Looks like with that old feed, one of two things may have happened:

  1. Solid core broken with ladder guy shoving through whole in wall (hit the ineternal wall and “bunched up” at an accute angle)


  1. Looking at the mast, he’s tried to be tidy and cinched the coax in tight against the mast… Where the coax comes out of the n-type on the bottom of the ant, it literally comes at near right-angles over to the mast… >:( . Again, either another core break or it’s virtually ripped it out of the n-type…

Moving on…

I’ve now got the fA ant running internally (center of roof space, as my previous), and its running at least as well as my previous well-working antenna! :slight_smile:

Also, bearing in mind I havent tweaked the gain back down from MAX trying to get the external ant to work - but will fiddle with that later.

I’m getting c220 mile range W and E, and after a week or so testing, I’ll look to move it back to the roof top, so it’s not limited by the end walls.

Day View…

I add the new ant last night (28th) at c19:00.
Also, bear in mind Gain is still at MAX (hence the noise / Single msg rates being so high).
I recall seeing a fomrmula for working out a good gain level on here somewhere recently, I’ll see if I can dig that out).


Week View…