Welllllllllllll
Three days work and all for nowt
Let me explain
I live close to a factory estate, and in the various units they use all sorts of gear.. Electroplating baths, welders, BIG lathes, electronic packing gear, automated robotic assembly lines... You get the picture....
All this means that I am close to a vast array of interference... So much so that back in the day when I took it all sooooooo serious, I would pack some gear in the motor, drive a few miles and set up a 'portable' radio station as it was, and still is, the only way I could receive any stations that were not giving a really strong signal
For those who may have used CB radio ( or indeed are short wave listeners of hams ) the 'noise' level ( interference ) is always S7 to S9 on the meter ( for those unfamiliar the meter in question show the strength of the signal you are receiving.. It goes in steps, 1 to 8 and then there is a section above the 9 showing the strength in dB relative to an S9 signal
As you can imagine, a base level of interreference reaching an average of S8 severely impeded my ability to receive signals except from really strong stations
It has always been the accepted wisdom that vertical antennas are less prone to man made ( what is referred to as QRM ) interreference
Seems I have proved without a shadow of a doubt that it is not always the case
Spent the morning fine tuning the antenna and was quite pleased with the result ( an antenna's length is critical and has to be adjusted to 'match' the frequency it is to be used on ( again, those who have used a CB radio will be familiar with this concept as at some stage they will have come across SWR.. Standing Wave Ratio, which ensures what you transmit goes OUT and is not bounced straight back in to your radio )
Ran the coax up to the radio shack and in to the radio
On every band the received signals were exactly the same as those received on my existing antenna ( G5RV for those interested ) but the noise levels ( interference ) rose !!
So sadly, as I said, it was all for nothing and I will be adding a rather posh multiband vertical antenna to the for sale list