Last Thursday the £500 equipment was stolen from his car, which was parked near his Gosport home.
Mr Hobbs said: 'It's life or death. Every minute counts when you are trying to get to the scene of an emergency.
'I go only to category A incidents such as heart attacks or people with severe breathing difficulties.
'I will always try to arrive within five minutes of receiving the call.'
By day Mr Hobbs is a security worker but he gives up his spare time to go out on emergency calls on behalf of the charity Community Responders. He was trained by Hampshire Ambulance Service in basic life support, using defibrillators and how to treat a range of potentially life-threatening conditions.
But as the Community Responders is a registered charity, all its equipment is paid for through fund-raising and donations.
This means the organisation has little funds and can't afford to buy a new sat-nav system.
gary.cleland@thenews.co.uk