so our ARES group has a county-level exercise coming up in about three weeks and i've been tasked with figuring out the power situation for our main communications node. we're talking two HF stations running simultaneously, probably an IC-7300 and an old TS-570 that one of the guys is bringing, plus a handful of VHF/UHF stuff for local coordination. maybe a digipeater node too if we can swing it.

my question is basically whether its worth dragging out the generator or just going full battery/solar. last exercise we used a Honda EU2200i and it was fine but it was also kind of annoying — noise, the fuel logistics, someone had to babysit it. i've been looking at running a couple of 100ah LiFePO4 batteries with a 200w folding panel and a decent MPPT controller but i honestly dont know if that's enough sustained current for two HF rigs both potentially running 100w for like 8 hours.

on the antenna side we're planning a linked dipole for 40/80m hung between two telescoping poles, and probably a vertical for 15/20m. the site is kind of a big open field which is good but we have basically no trees so everything needs to be self-supporting. anyone done something similar and have thoughts on the power math or what's actually worked for you in the field?

the power math on this isnt terrible if you're not both running 100w continuously. realistically in a comms exercise you're probably averaging maybe 20-25% duty cycle on transmit, so two rigs at 100w out might actually pull something like 25-30A average combined depending on efficiency of the finals. the 7300 is pretty decent on power consumption, draws around 22A on transmit at 100w and like 2A on receive. the 570 is a bit older and probably pulls a bit more but similar ballpark.

two 100ah LiFePO4 packs gives you 200ah usable (basically all of it with LiFePO4 which is nice), so even at 30A average draw you're looking at like 6.5 hours before you're getting low, and thats without any solar input at all. with 200w of panels on a decent sunny day youre probably adding 8-10A back in during daylight. so yeah it should be workable but its tight if the exercise runs long or if conditions are bad and people are cranking power trying to make contacts.

personally i'd bring the EU2200i anyway just as backup. leave it off unless you need it. the noise thing is real but you can run a longer cord and stick it downwind, it makes a huge difference. had a similar setup at a public service event last summer and ended up needing the genny around hour 6 when clouds rolled in and the battery was getting low. really glad i had it in the truck.

for self supporting in an open field with no trees, look into the Spiderbeam fiberglass poles if you havent already. the 12m one is pretty solid and packs down to nothing, we use them for field day every year. you'll need good guying though, any wind at all and a unsupported 40 foot pole with wire on it gets sketchy fast. we had one come down mid-contest a couple years back and it landed on somebodys car which was not a great moment lol.

also on the linked dipole — make sure your feedline routing is thought out ahead of time because it can get real messy real fast with two stations and you dont want common mode problems coupling between the two HF rigs, especially on adjacent bands. choke baluns at the feedpoints and maybe a line isolator on at least one run. just something to keep in mind.