Remote range
#1
11-05-2015, 07:28 AM
#4
11-06-2015, 04:32 PM
Here is the post. If you haven't done this yet . . . . do it now !! I put some cable shrink wrap on mine.
Makes a marked improvement on range. I hope he doesn't mind me passing this on.....
Remote Keyfob Range Improvements
Postby Equinoxstudios » Thu May 10, 2012 10:11 am
The late model XJ40 has an RF type keyfob for remote lock/unlock/windows close/headlights on feature. It operates on 418MHz for the UK version and 433MHz for the rest of the world.
The range of operation was considered adequate back in the early 1990's but because there's a lot more radio interference around these days it might struggle to work only a few feet away from the car.
Here's a simple modification that will increase its range significantly. First check you have a new battery! Then solder a piece of tinned copper wire to the circuit board as shown here. Bend the wire over as shown and cut it to length suitable so it doesn't quite reach the battery. Make sure it doesn't touch any other components. You could put a bit of sleeving on it but I just couldn't be asked
Here's a close up. Soldered to the end of C5 at the junction of C5 and R5/C6...
For the true technically minded amongst you, here is the actual application note from the manufacturer of the RF device used in the keyfob...
The part shown as "SAW" is the resonator used to generate the radio frequency energy. The L2 and C5 series filter components shown in the schematic are replaced by parallel RC components C6 and R5 which go to ground on the keyfob PCB. You can play with the values of the base resistor R3 (R1 on the schematic) and the output filter R5 and C6. I did replace the base resistor with a lower value of 22K which made a small difference but this will also affect battery life so that is up to you if you want to do it. The antenna wire modification is essentially soldered to the collector of the transistor buffer. I know the impedance match is going to be pants but it's an improvement on a pants performing remote!
1994 XJ40 Sovereign 4.0 Brooklands Green
Surrey Hants Border xj40.com Regional Rep
email: surreyhantsborder.xj40com@gmail.com
Makes a marked improvement on range. I hope he doesn't mind me passing this on.....
Remote Keyfob Range Improvements
Postby Equinoxstudios » Thu May 10, 2012 10:11 am
The late model XJ40 has an RF type keyfob for remote lock/unlock/windows close/headlights on feature. It operates on 418MHz for the UK version and 433MHz for the rest of the world.
The range of operation was considered adequate back in the early 1990's but because there's a lot more radio interference around these days it might struggle to work only a few feet away from the car.
Here's a simple modification that will increase its range significantly. First check you have a new battery! Then solder a piece of tinned copper wire to the circuit board as shown here. Bend the wire over as shown and cut it to length suitable so it doesn't quite reach the battery. Make sure it doesn't touch any other components. You could put a bit of sleeving on it but I just couldn't be asked
Here's a close up. Soldered to the end of C5 at the junction of C5 and R5/C6...
For the true technically minded amongst you, here is the actual application note from the manufacturer of the RF device used in the keyfob...
The part shown as "SAW" is the resonator used to generate the radio frequency energy. The L2 and C5 series filter components shown in the schematic are replaced by parallel RC components C6 and R5 which go to ground on the keyfob PCB. You can play with the values of the base resistor R3 (R1 on the schematic) and the output filter R5 and C6. I did replace the base resistor with a lower value of 22K which made a small difference but this will also affect battery life so that is up to you if you want to do it. The antenna wire modification is essentially soldered to the collector of the transistor buffer. I know the impedance match is going to be pants but it's an improvement on a pants performing remote!
1994 XJ40 Sovereign 4.0 Brooklands Green
Surrey Hants Border xj40.com Regional Rep
email: surreyhantsborder.xj40com@gmail.com
Last edited by malc4d; 11-06-2015 at 04:37 PM.