Attempt to setup for 20m – interference

Example of interference on 20m - 14070

Example of interference on 20m – 14.070 MHz

My long term goal here is to have an inverted V for 40m. However the other week I was looking at my 10m vertical in the garage and started wondering what I could throw up in the short term for HF. It then dawned on me that between the eave support for my 2m/70cm antenna and a pole in my back yard for an old arbour I’m pulling down, there’d be just enough space for a 20m dipole!

So last week-end I finally got a basic dipole up, tuned it and the SWR was looking good! I attempted some WSPR and I was happily receiving stations from America and Europe (albeit, my shack computer currently has no network connection – so I was unable to post spots). In return, I could see I was also making the same distance.

However shortly after that I realised this was causing TVI. I thought this was surprising considering it was low power and at 20m, however whenever I transmitted I immediately trigged a ‘No or weak signal’ message on my TV.

Example of interference on 20m - 14070

Example of interference on 20m – 14070

Easy fixed, I wont transmit until the week-end (when I’ve time to investigate and address) and will just attempt to receive some SSTV. But this turned into a rather mediocre result and led me to look closer at what I was receiving. I then realised there was little point fixing the TVI issue as I was going to have trouble even receiving!! The image on the right is what I saw (which is also reflected in the S meter sitting up at a solid 9).

The image was taken at 14.070 MHz as one of the main things that attracted me to 20m was the hope of lots of digital work – and that’s focused between 14.070 and 14.090. But up at 14.230 (the SSTV calling frequency) the image was similar albeit the lines are more straight/constant.

Anyway, I did the normal thing and turned off the power to my house and ran on battery supplies. But the issue persisted – indeed, it didn’t seem to change at all. So I guess there’s some localised interference, but I’m not entirely sure what this pattern might be caused by or indeed what my next choices might be. I’m kind of just taking it as a sign that 20m  is out… But that said, if you recognise this pattern (or have suggestions) please jump on in and leave a comment.

10mComparisonAs a comparison, I thought I’d see if I could tune the dipole up on 10m an see what that looked like. The image to the left shows the result. Further to this though, I was able to happily send and receive WSPR to America as well as the reception of a couple of SSTV images also from America.

So whether that means I cut the thing down to size for 10m and just go with that until I get my proper 40m setup done… I don’t know. Anyway, it’s the end of the week-end so I guess I’ll just have to ponder it a bit.


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