so ive been running a cheap radio shack dual band collinear for the last couple years and its finally given up the ghost, connector got corroded and the SWR went to garbage. time to replace it and im trying to decide between the diamond x50 and the comet gp-3. both seem to pop up a lot when people talk about base station dual band antennas but i cant really find a straight answer on which one actually performs better in the real world.

my setup is a yaesu ft-7900 running into about 40 feet of LMR-400 up to the antenna on a push-up pole on the side of my house, probably 25 feet above ground. mostly doing local repeater work and some simplex when the nets get going, occasional APRS too. nothing crazy. i just want something that doesnt feel like im transmitting into a dummy load.

i know both are 6db gain antennas on paper but ive heard the comet can have some issues with the center section joint loosening over time? maybe that was an older version. anyone actually run both of these and have an opinion that isnt just repeating the spec sheet

ran the x50 for about 4 years up here in the pacific northwest which is not kind to anything metal and it held up pretty well honestly. the connector housing did show some surface corrosion but i hit it with self amalgamating tape right from the start so no issues inside where it counts. never touched the SWR after i got it dialed in on install day, stayed basically flat across the 2m portion.

cant speak to the comet gp-3 directly but a buddy of mine who does a lot of packet and APRS swears by it and he's had his for probably 6 or 7 years without touching it. his is in a worse RF environment than mine too, closer to some commercial broadcast stuff. so honestly i think either one is going to be a massive step up from what youre replacing, i wouldnt lose sleep over the choice. just make sure you weatherproof whatever connector is at the feedpoint, thats where those cheaper units always die first and even the diamond isnt immune to that if you leave it bare.

the joint thing on the comet is real but i think they sorted it in newer production, the one i bought like 3 years ago has been fine. what i'll say though is if youre doing APRS regularly you might want to think about whether 6dB gain on a collinear is actually what you want for that. higher gain narrows your vertical pattern and if youre in any kind of hilly terrain you can actually miss stations that a lower gain antenna wouldve hit. just something to consider, probably doesnt matter for repeater work but aprs can be weird about it