BeElion(TM) 12-Pack SMA Male Crimp Straight Connector, RF Coax Adapter For RG188 RG178 RG316 RG174A-U/LMR100A/RFC100A Cables

Q: What size die is used to crimp the center pin and outer barrel?

I don't know that you can reliably crimp on the center pin. The smallest die I had was 0.042" and I wasn't comfortable that the pin would hold. In general, I opt to solder the center pin even if it is a crimp-on connector. For the barrel, I used a 0.128" die which seemed to work well.

Q: Can someone recommend the proper crimp die #/size to use on these barrels? Thanks.

if you check the crimper's data and it should tell you what size cables it work for. that should be enough information.

Q: Can these connectors be used to replace connector on a pc antenna

Probably if the antenna has one of the small cables listed in the data on the connectors. It does take some soldering skill to solder the center connector and a chrimping tool to crimp the ferrel around the cable

Q: Pin size ,what diameter is it?

You can refer to the 6th product image, it indicates the diameter of these connectors. Also pin size is standard for RG188 RG178 RG316 RG174A-U/LMR100A/RFC100A Cables, appreciated.