so ive been doing contests for a few years now mostly single op single radio and lately ive been reading a lot about SO2R and wondering if its actually worth setting up for someone who maybe does 4-5 contests a year seriously. like i get the concept, run on one radio while the other is searching and pouncing, but every time i start reading about it the station engineering side of it just seems like a rabbit hole that never ends. bandpass filters, antenna switching, keeping the second radio from blasting your ears out through the headphones... it feels like a full weekend project just to get the setup stable before you even key up.

my current setup is a 7300 as the main rig and i have an old ft-857d sitting in the shack doing nothing. theoretically i could use that as the second radio. but the intermod situation between two transmitters in the same shack on different bands with my antenna situation (two yagis on a single tower, not stacked, just kind of aimed different directions) seems like it could be a real mess. anyone gone through this and actually come out the other side with something usable without spending a fortune on filters?

also curious whether the rate improvement is actually noticeable for someone running 100w or if SO2R really only shines when youre running high power and already pulling good rates on the run radio

honestly the rate improvement depends a lot on your operating skill before you even think about SO2R. if you're not already pretty comfortable managing a pileup and doing efficient S&P transitions on a single radio, adding a second one is just going to split your attention and hurt your score. i went through a phase where i thought SO2R was the magic bullet and my scores actually went down for two contests before i got my head around the workflow.

that said, once it clicks it really does work. the classic use case is you've got a good run going on 15m and 10m is opening up but you dont want to abandon your frequency. second radio lets you cherry pick the mults without giving up the run. at 100w you're probably not going to be pulling 150/hr rates anyway so the absolute gain in QSOs per hour might be modest, but the mult efficiency can really add up especially in something like CQWW where a new zone on the second radio while you keep running is basically free points.

re your filter question -- yeah the 857 and 7300 on the same tower is going to need at least some bandpass filtering if you're transmitting both simultaneously. the 4O3A or Dunestar filters are the usual recommendations, not cheap but not insane either. if you're only doing a few contests a year you could probably get away with being careful about which bands you pair and just accepting you wont transmit both at exactly the same time, which is what a lot of casual SO2R ops do anyway

the 857 as a second radio is actually pretty decent for S&P work, i used one for a while in a similar setup. the main annoyance is that the IF DSP isnt as good as the 7300 so pulling weak ones out of the noise on the second radio takes more effort. but for grabbing mults and keeping an ear on a second band it does the job.

one thing nobody really talks about enough is the SO2R workflow in the logging software. N1MM has SO2R support built in and once you get the radio focus switching set up correctly it saves a ton of fumbling. i spent more time messing with that config than i did on the RF filtering side honestly. the alt-tab workflow or using a footswitch to flip between radios becomes pretty muscle-memory after a while but the first contest you run it everything feels weird and slow