¦ Article ¦ HF-projects¦ 6 to 1 HF-antenna switch¦

A ON5ZO / ON4BAI Project

!!!!!!! UNDER CONSTRUCTION !!!!!!!!!!

Last review: 15-12-2005

As time goes by, almost every OM will find himself with more than average antennas in the backyard or on the roof. Good coaxial cable is not cheap and a way to have several antennas available in the shack over only one excellent coax cable is a remote switch. Untill now I switched my antennas "manually" by swapping one of my 2 55 meter runs of RG-213 coaxial cables to several of my backyard antenna projects...

We can of course go to a commercial site and buy the necessary gear. Providers like microham and array solutions provide very nice equipment for every possible antenna situation. However, my friend ON5ZO pointed my an article form QST. It was a nice project by KO4NR who developped a nice 6 to 1 switch.  While discussing several issues we encountered a few problems which we needed to tackle. For example, the the relais used were ZETTLER AZ755. Those relais, although rather commonly used, we could only obtain replacements types in Belgium. Franki, found out the relais used by microham and we could easily order them through CONRAD in the Netherlands. The relais we used was a 12V relais by TAKAMISAWA, the VSB12STB at about 2€ a piece.


Printed circuit.
KO4NR's antenna switch project uses a printed circuit board from FAR circuits. The circuit board is nicely designed and the antenna connectors ard soldered directly to he board providing short connections to the relais for minimizing VSWR problems. We ordered the printed circuits by 4 pieces. The boards were send out of the USA without import problems in ON-TAX land.

Schematic diagram.

Here comes schematic...




Inductance (XL) for the radiator.




Ground Losses (Rg).




VSWR and bandwith.


If you

  40 Mete


The lower t

Impedance Matching.

If your

A trifilar trafo on a TX 36/23/15 - 4C65 core.The u=125 and AL=170. Available at www.dx-wire.de. I used 3 windings for this trafo. More info at ARRL antennabook 20th edition, page 11-43.



I made



  • This


1/ARRL Antenna book 20th edition

5/EZNEC 3.0 from W7EL/ www.eznec.com

6/Hamcalc from VE3ERP.