what's the best way to test the operation of the Hirschmann (sp?) antenna now that it's out of the car? The car seems to have an original cassette player, I think it says Becker/Mexico? something like that, I hope it works, would love to test out some old Dead & Little Feat tapes from about the time this car was made. I also have a guy down here who fixes all these old stereos, I have yet to stump him; "Telstar" audio repair, he runs his operation out of a bunch of ad-hoc connected U-Haul storage spaces here in Austin.
if i understand well and the hirschmann antenna is an automatic one, you will normally have three cables plus the antenna signal coaxial cable: black for ground (battery minus), and another two for operation, colours may vary, but usually one is red (poistive battery) that is power, and another green or white that triggers the power, this is essentially a positive but it comes usually through a switch included in some radio models, or an external switch (my setup)
test operation is simple, use you battery, you connect black to batt neg, red to batt poistive, and then you touch batt positive with the other (green/white) cable, as soon as you touch the antenna deploys out of the tube, if you remove the contact of this cable from batt, the antenna goes into the tube again and closes
some other models have a more complex setup including a relay, i may have schematic drawings, let me know
a tip, a friend prepared his setup including a switch that cuts both positive cables at the same time, this allows him to have the antenna stop in intermediate positions between close and open
hope this helps