Transmission1

hi guys hope you all had a good Christmas I have noticed a problem I have an antenna problem my antenna is in the attic just waiting till new year now to get it out side now since the roofs are done anyway when I press the ptt on my radio which is set to 10w with the x30 the smoke alarms in my flat go off just mine no one else's in the block so I took that antenna down and put the x50 in its place press the ptt with the same coax 10w same radio and nothing goes off so am I righting thinking the x30 is faulty I have checked the swr on the x30 and its flat on 2m then 1.2 on 70cm and the results on the x50 are more or less the same never heard of this first time its happened I am going to get antenna analyzer

Might just be how the antenna is radiating. Try moving the X30 to a different location in the attic

tried all that still does it never used to happen first started when the scaffolding went up and now its all gone still does it but I have no problem with the x50

The radiation pattern of these two antennas should not be massively different, it might be that the matching is not so good on the x30 and it's radiating from the coax outer. Presumably your smoke alarms are connected together by wiring running above the ceiling? If you know where it runs, it might be worth moving your coax away from it. If you have one, it might be worth fitting a choke to the antenna end of your coax, or if you have a bit of spare coax just coil it up reasonably tightly (but not so tight as to damage it).

am using the x50 at the moment in the attic anyway at the moment until I get it out side with no problems just thought I would ask thanks guys