I agree with Jeff. The lines to each element are 50-ohm. They can be any length, but must be equal in length. Connect to the tee. Then a 1/4-wave section of 35-ohm cable. This brings things back to 50-ohms. At that point connect any length of 50-ohm transmission cable.
Chuck WB2EDV ----- Original Message ----- From: "Jeff DePolo" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Thursday, March 06, 2008 11:19 AM Subject: RE: [Repeater-Builder] Re: DB 212-2 Harness info. >> What this does with antenna element at 50 Ohms then 1/4 wl >> down the 35 Ohm cable it looks close to 100 Ohms looking into >> this cable. > > No, that's not right. If the element were 50 ohms and you attached 1/4 > wave > of 35 ohm cable, you would transform it down to 25 ohms, not up to 100 > ohms. > You could transform 50 UP to 100 via a 75 ohm odd-quarterwave cable. > >> The length of the 50 Ohm coax going from the tx/rx to this >> antenna input does not matter for SWR or impedance. Only >> concern would be length and loss of 50 Ohm cable. > > Just to be clear, the length of the 50 ohm cable doesn't matter at the > input > to the antenna, but it DOES matter within the harness itself even if the > cable isn't being used as a transformer. The bays have to be fed in-phase > otherwise uptilt/downtilt and elevation pattern distortion will occur. > > --- Jeff WN3A > > > > > > > > > Yahoo! Groups Links > > > >
