[Lowfer] Earthing - probes

[Howell, Laurence (Shanghai/Singapore)]

As others have point out each location appears with a different challenges. Most of the successful reductions in non wanted noise appear in the form of isloating any dc amp probe feed interference (that's rubbish obtained from the power supply by making the dc feed high impedenace to rf, and secondary decoupling the rf coax outer from noise picked up from the shack and carried to the probe on the outer of the braid or whatever.

Don't use switched mode supplies so rx or probe feeds unless they are very very very screened and cleaned -!!!!


My best and most effective solutions have been a combination of both these using info linked from the on7yd web site by an article from a " wb " someone (sorry I'm not on my home computer but presently typing this on my blackberry in a houston walmart!)  Who deals by choking and decoupling  both the neg and pos dc supply and transformer isolating the feed too at the rx end. Secondly earthing the coax or in my case connecting the coax to a house entrance door and window really is the main improvent effectively sets up the house as a farday cage trapping and dumping the internal noises to "ground" before getting to the antennae. Thirdly I have a large toroid in a box with some 30t of rg174 terminated on insulated bnc set in a small metal box - this is the last line of defense to choke off any residue but it doesn't do a lot. The inductance is around 5mH.

Sorry for the typos as my shopping cart is being bumped...

Laurence KL 1 X mobile 5
Tstorms