I did go back to the website and I'm seeing it says its a BNC fitting.
I see you wrote the above - that's weird. Using the model number and Google it send me here:
RHWA-450-STM: 10 Inch Tuf Duck Style Base Loaded 1/2 Wave Antenna - 450 Mhz UHF TNC.
And no mention of "BNC" only TNC.
Can you send the link to the website you are talking about?
Ahh! I think I see - I looked on the Arcadian website and think I found the actual antenna you are referring to. Different model number than the one you posted which is why we were confused:
RHWA-450-SBM: Scanner Antenna for Portable Hand-Held Police Fire EMS & NASCAR. Hi-Performance, Long Range For UHF & VHF with BNC.
TNC version is RHWA-450-S
TM.
BNC version is RHWA-450-S
BM.
Yes, according to the description for this model it does use a BNC. But, again, maybe something is wrong with the BNC on the one you got that is causing it not to be able to twist on all the way? If so, I would send it back and try and get a replacement.
ANd the TNC to BNC adapter won't help you if that is the case, sorry. Since you already purchased it then I guess you could either return it or keep it for possible future use. Adapters are always useful sometime down the road.
-Mike