> Why is it using that two pin connector? http://www.ebay.com/itm/142110850556 The R-13 is part of the A.R.C. Type 15 VHF navigation system. The R-13 provides both VOR and LOCalizer functions. The antenna A-13 is a VHF dipole which feeds the R-13 through twinax (two-conductor) cable, required for the localizer function. Mike / KK5F