As you stated, you never can tell how many tours you‘ll get. Having said that and assuming you‘re using "Rad Op" with it‘s traditional association with the Army...
In my experience, Sig Ops (Rad Ops were rolled in with Tel Ops several years ago due to computerization) are one of the trades in most demand and have traditionally had a higher than average number of tours. It‘s not all that rare to see guys with no CD with 4+ tour medals.
Having said that, the Land Force currently has a policy whereby you are unable to be deployed within 12 months of returning from a 6 month tour. Waivers may be considered for personnel who really wish to go and where there is a desperate need for their skills but you can‘t usually be ordered on the plane.
With ASD (Alternate Service Delivery) having been implemented in Bosnia, the required number of Sig Ops per tour has dropped dramatically which is easing the strain somewhat. However, Sig Ops still do go into Bosnia, usually the choice locations of the remote RRB sites on top of mountains and if the CF goes on a tour in any kind of numbers, you can be sure that Sig Ops are going as well. So if your wife really, really wants to get you out of the house, she should be able to swing it fairly easily.
Lastly, although there are Garrison positions for Sig Ops, the vast majority of the positions are with Units such as an HQ&Sigs Sqns, Infantry Bns, Armoured Regts etc. Your first posting will be to one of these, usually the Sig Sqn, so you can gain the most experience with your core capabilities in the least amount of time. Don‘t forget that these regularly go on Ex and fill individual tasks which will take you away from home for periods of time. These aren‘t usually overly long but can easily add up to 3-4 months per year, depending on the cycle the unit/Bde is in. Throw in a course or two and suddenly you‘ve been away for 6 months without the little bonuses you get for going on tour, which is why some guys jump at any tour which comes along.
Anyways...not trying to scare you out of joining, just giving you some facts as I know them.