VHF telemetry repotting

[xaocam]

Hi there
I am a (poor) wildlife researcher and I am trying to re-pot (replace batteries) in small wildlife VHF tracking collars (tone beepers); however, I have a problem. I have replaced the batteries using the exact same brand and type Fujitsu CR1/3N, the problem is the transmission strength is no where near as strong as what they used to be. Strangely though if I touch the battery with my fingers, the transmission strength is very good. Could someone please explain to me why this is so and a possible solution to increase the transmission strength.
Many thanks
Cam

 

[Harald Kapp]

Your fingers, your body act as an antenna.
Did you (inadvertently) disconnect any antenna-like structure (wire, PCB with meandered traces etc.) from the tracker when opening it for changing the battery? Obviously you're operating the tracker with open case (how else would you touch the battery during operation?). Have you tried closing the tracker fully? The housing may be part of the antenna structure provided by the manufacturer.

 

[xaocam]

Hey Harald
Thanks for your reply
I am a complete pillock! hahaha. The manufacturers Mhz was 151.2060, which is what I was trying it on, and yeah, I kinda figured I was acting as an amplifier but I had a memory in my head from years ago about looping a copper wire inside help amplify.....but I was somewhat dismissive of it being a questionable memory. In the end though I actually questioned whether the manufacturer had made a mistake and lo and behold, 151.2080 was the MHz, so all is good................................................................for now
cheers mate

 

[shrtrnd]

Considering the fact that these are presumably used outdoors, when you change batteries, I'd clean the battery
contact points to make sure the batteries make good electrical contact.