Hi,
The No19 Wireless set had two antennae mounted on two bases. The one on the small square panel behind the turret hatch is the A type antenna and is shaped like a post, either with or without the circular cage. The one in the circular depression at the rear of the turret is the B type antenna base and is shaped like a cone.
There are some photos here:
http://onesixthnet.yuku.com/reply/121954/Re-Wireless-Set-No-19-in-British-AFV-
Erik L