Topband: Loop and beverage coupling

[Ron Tremayne VK3IO]

Hello Harry and all topbanders, from down under, with a big hole in the ozone (ionoshere) layer.

The only way to  make sure the loop does not interact with the beverage and therefore degrade its performance is to use relay switching to detune the loop while listening on the beverage.

That is to switch the loop to another tuner, that is tuned to for example to 80 mtrs while listening to 160 on your beverage.

Another answer is to adjust your feeder length so that when the loop is open, circuit while listening on your beverage, the loop is detuned by the inductive loading of the feeders and the loop will have a new reasonant frequency out of band (this also require relay switching to acheive this).  

Do not just short out the loop as this will introduce a similar effect as having a "shorted turn" in an electromagnetic circuit and further reduce the performance of the beverage.

The above is true for any antenna 1 and antenna 2 situation, where both antennas are tuned to 160, but when your listening on one antenna, the other one, if it is close by will interact (by close by I mean within one wavelength seperation).

I use open wire feeders and have no trouble using simple 24 volt DC coil, 240 volt 15 amp contact AC motor control relays to do the feeder changeover (even up to 10 metre band). Of course we are only allowed 400Wpep down here.

good luck Ron vk3io  vk3io at iinet.net.au