----- Original Message ----- From: "Ken Swaggart" k.swaggart@charter.net To: "AMSAT-BB" amsat-bb@amsat.org Sent: Wednesday, March 19, 2008 12:49 AM Subject: [amsat-bb] Replacement KLM 2M-14C matching harness coax?

It's time to rebuild my Oscar 10 vintage KLM 2M-14C matching harness.

There

are no markings on the original harness but it has teflon insulation and I assume it is 75 Ohm. Anyone have the replacement info? I'd prefer to use teflon cable. The antenna manual doesn't describe the matching harness.

Tnx, Ken, W7KKE

Hi Ken, W7KKE

The balun across each folded dipole is made with 50 ohm RG-303 teflon insulated coax cable, velocity factor 0.694

The phasing coupling harness is made with two matching lines of 75 ohm RG-302 teflon insulated coax cable, velocity factor 0.694

The polarity switcher is a relay Guardian Electric WJ MFG Corp 1365 series 12 V dc A410-364385-00

Due of the lenght of relay the lenght of coax RG-302 going from relay to the 50 ohm unbalance feed is critical to be 1/4 electrical wave long beginning from the folded dipole so that use only 75 ohm RG-302 or any other type of 75 ohm teflon insulated coax with the same lenght as the original one.

For water protection it is necessary to enclose the PCB and relay into an additional plastic box and if anyone is interested on it I can send a set of pics showing my own installation.

73" de

i8CVS Domenico