Since the Oncore I bought from bgmicro uses 5V, and also needed RS232 level conversion, I built a circuit to handle both - taking the 12V from pin4 on the sled.

I also bought an Sv6 from bgmicro for $25 that did come with an antenna, and used the antenna for the Oncore. Since I had to buy a 30ft roll of RG174 cable @ ~$30 and then crimp connectors to suit, it ended up costing more than justing getting an active antenna with cable from ebay for around $30. Oh well.