Polar F6
You can try to use HR cream or good old-fashioned spit to start with--the fact that it comes back to normal after 20 minutes suggests that as you sweat it starts picking up signals again. But this could be any number of things. You could have a dying battery in the chest strap (easily replaced) or wrist unit or you just have a malfunctioning wrist unit.
1 other possibility--interference from a nearby utility line. My cheapo Timex HRM would consistently read 225 when running near power lines and then revert to normal; my 725x does not have this problem. I'm not sure if the F6 is susceptible, but many HRMs are.
I have both an F series Polar and an S150 and both will fritz out from time to time like that. I seriously wet down the contact patches (I have the soft WearLink model) before I put it on, but sometimes it dries out before I cna work up a sweat. Also doesn't help that I am in AZ and the air is do dry, sweat evaporates instantly. It also may have something to do with the shape of our chest not providing an ideal contact area.
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Bryan
Of course it's 'effing hard, it's IRONMAN!
A steady number for 10 minutes would make me think there might be a problem with your monitor instead of an error with the transmitter or external interference.
You should try it under different circumstances and if the same problem comes up, you should take it to a polar dealer.
Hyperactive Trifueler!!!! (I refuse to let the status go :p)


Hey guys,
I just got a Polar F6 and although it works fine when I start working out, after maybe 10 minutes the watch starts reading a number that's wrong (i.e., 78 bpm yesterday during a tempo run) and just leaves that number there for another 10 min or so before working again. I've only used it for two workouts so far (I've only had it 3 days), and this has happened both times. I was thinking maybe the contacts were drying out (or maybe not)? Maybe I should use vaseline or something (a la an EKG) to keep the contacts working? If anyone would like to share some wisdom, it would be greatly appreciated!
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-Matt
Not fast enough.