so ive been running a diamond X50 on the roof for about two years now and it works fine for hitting the local 147 repeater but theres one machine about 40 miles out that i can just barely key up on a good day, like if the weather is right and i run 50w from the shack. been thinking about whether a yagi would actually help here or if im chasing my tail.

the thing is the repeater is roughly NNW from me and my house kind of blocks that direction at low angles, i think. i put the X50 up pretty high, maybe 30 feet on a chimney mount. the other option i was thinking was just a longer collinear, like the X200 or maybe a Comet GP-9, get a couple more dB of gain and see if that does it. but someone at the club last week was saying a 5 element yagi pointed at that repeater would wipe the floor with a collinear for a fixed path and i cant really argue with that from a pure gain standpoint.

the problem is i dont really want a dedicated antenna just for one repeater, i use 2m pretty broadly for the club nets and occasional simplex. so i guess my question is, has anyone gone down this road and figured out a good compromise? or is a yagi just overkill for repeater work in general when youre not doing weak signal stuff

your club guy isnt wrong but context matters a lot. a 5el yagi on 2m is going to give you somewhere around 10 dBd depending on design, compared to maybe 5-6 dBd for a GP-9 type collinear - so yeah on a fixed path the yagi wins pretty handily. but you already said it yourself, you use 2m for general stuff so pointing a yagi at one repeater kind of defeats the purpose unless you motorize it or just accept you're giving up coverage everywhere else.

honestly for your situation i'd try the GP-9 or something similar first. going from 3dBd to 5-6dBd is still a real improvement especially if your current antenna has any feedline loss eating into things. what coax are you running and how long is the run? because 30 feet of RG-58 at 2m will kill more than you think and sometimes that's the actual problem before you even get to antenna gain.

i had almost the exact same situation a couple years back, repeater that was just barely there on a good day. ended up swapping to a GP-9 and it helped maybe 3-4 db in practice which was enough to make the difference. didnt bother with a yagi. for what its worth the GP-9 is a solid antenna but the mast mount on mine was kind of cheaply made and i had to redo it after the first winter, just a heads up if you go that route