wow, I have an OPEK antenna on my car Don,It might be a good idea that I check it, I might have the same issue as you did. I have an Antenex antenna for UHF, the phantom series antenna , I thinks its TRA4303 Its white, you can also purchase them in black TRAB 4303, these are 430-450 MHZ with 3DB gain and I have been able to hit chathams UHF machine from windsor. Antenex and MaxRad are a good commercial make for amateur/commercial/air craft/ marine/ as well as WiFi. I used to used a Maxrad VHF quarter wave and it worked very well with flat match, but when I went to the dual bander I didn't really want 2 antennas so i found this OPEK dual bander and have been using it for a few years now, but hearing what happened to you Don I will be looking into mine. I am not sure of the model number, this is an older antenna with the PL250 connector like yours. Personally I like NMO, I have NOT tested the Antenex dual band antenna. I see good reviews on them, they are a bit pricey but seem to be rugged.
You can find these antennas from a few places:
www.ebay.cahttp://www.theantennafarm.com/catalog/The antenna farm also has most commonly used antennas on ebay when you search Antenex or MaxRad
Adam
VE3 MUN