The actual summit at the 362m spot-height is located inside the Llansilin firing range. However it is possible to activate from a small mound at 350m located at SJ 23352 28874 outside of the firing range or the surrounding area (to the East/North East of this coordinate) which will be within the activation zone (consult OS map). Furthermore the summit proper is in dense forest which could make VHF very difficult.

Report 1
 SJ 24329 28401 - Room for one car just before junction.
 From the parking spot walk north towards the junction and turn left on the small lane and continue till the lane splits into two at SJ 23610 28726. Take right turning towards Pentregaer Uchaf farm and at farm go over stile into farm yard then trough a gate and then a second stile. At this point it would be good to ask the farmer for permission to go onto the land at the north (there was no one in at the time as I was there so I continued). Follow PROW to stile at SJ 23502 29151 (caution - there are electric fences here) and once over the stile look to your left and you will see a small wooden gate with an electric fence line in front of it which you can uncouple. Just make sure you get hold of the black handle made for this purpose otherwise you will get a nasty jolt and remember to put it back when through. Then aim for the high point a 100m ahead at SJ 23352 28883. If you can locate the farmer there is a shorter route though a gate, which is to the north, which they might permit you to use. Car to summit takes 40min, ascent 144m, distance 2.7Km.