but that requires extra components and (therefore) extra expense.

Probably right. Simplest solution is for them to do a QA check on the antennas before delivery with the unit.

So easiest way to check the Pflarm A antenna, if you have access to the box itself is simply unscrew it from port A. And get out an ohm meter and carefully probe the inner core socket(middle of the white nylon bush) vs the outer "nut" which is tied to the shield. It should read infinite. If using the continuity feature of your multimeter it should NOT sound the high pitched beeeeep. verify again. if good, carefully screw the antenna back onto the proper/same port A and careful not to cross-thread. do not attempt to attach to any other port.