Heartrate monitors (signal loss)

I use a cardio sport and a Timex HRM (not at the same time I might add). Now sometimes I can run for well over an hour with no problems. Other times I am less than a mile down the road before I start getting loss of signal. These clear up (mostly) and the monitor reports correctly my heartrate again. However I then get the monitor losing signal two or three times every 10 minutes. How can it work well for an hour or more with no signal loss one day and other times be a complete waste of time? Any advice on positioning of belt, what to moisten the belt with...etc would be appreciated. Oh I tend to soak my belt in a sink for a minute or so before the run.

Various possible causes:

Interference from overhead cables or other strong signals. This is the reason why HRM's don't work inside cars (at least my HRM doesn't work in my car, when the engine's switched on)

Contamination of chest strap contacts with vaseline, etc.

Strap too loose.

Chest too hairy causing poor connectivity.

The belt must be moistened with some sort of saline solution (spit or sweat!) otherwise you won't get an electrical circuit (ordinary water is not a good conductor)

Are the batteries beginning to run out?

There may be more reasons but these are all the ones I've experienced.

Hope that helps.

My new HRM (Polar S210) seems much more sensitive than my old one (Nike HRM]Triax) and not in a good way - running along the Thames I seem to be continually passing strong electrical sources which cause the thing to go absolutely bananas - I got a max. reading of 238 yesterday at one point!

Loss of signal though is more likely to be a bad connection as Drew rightly says - and yes, spit works much better than tap water!

Ive got Polar S210 too,I find it often reads 00 or 200 for the first few minutes of use (really annoying in a race where that early excitement throws my pacing altogether).I think it may have been caused by my car remote/key which was in pocket on same side as the receiver - so I now stash key around neck with better results.

Ahh, I did realise it had to be a saline solution. It seems so obvious now I know that it needs to be a good conductor (DOH!). Thanks for your help, I am off to spit on my strap and see if I get on any better.

If you were actually soaking your strap in a sink with water it could be that is has a slight leak and water was getting in the works. Stick with spit!!