[HarryM1BYT]

Grateful for the thoughts of the forum on this. I have one of Seans "double din" sets, and have some issues with the radio reception. It wasn't too bad to start with, but since fitting an aerial splitter to feed both the main unit and TMC from the same aerial, the reception has worsened (to be expected I suppose).

Reception is bound to be a little worse, because the splitter is unlikely to be an impedance matching type. The antenna expects 75 Ohm being presented to it but is seeing something less than 40 Ohm and the signal is being shared between the two anyway - but it should still work reasonably well. Could the splitter perhaps be faulty?

If you have a multi-meter - Between the centre terminal base of the Y and each arms centre terminal you should see zero Ohms (or a steady 30 to 40 Ohms if it is a matching type). Between the outer of any plug to the outer of any other plug, you should also see zero Ohms (or something very close to zero).

The older radios would be fitted with a little trimmer in the back, so you could peak up the reception to better match the feed impedance.

To check my connections, I clipped the electrical screwdriver to the end of my improvised power lead, and "earthed" the screwdriver tip on the cars body work. The bulb lit up, confirming power. I then put the screwdrivers tip onto the power feed terminal of the amp. Nothing. No lit bulb, no improvement in reception.


So, does this mean that my aerial amp is simply not working? Am I right in assuming that the screwdrivers bulb should have lit up when connected between the amp and it's power feed? Or is it simply that the later (non diversity) aerial amps are not really up to the job?

The clip on the test lamp needs to be connected to a good ground, the lamp should then light when connected to any point which has +12v on it. If, with your system switched on, it doesn't light with the probe on the supply to the amp, there is a problem.

I have not tried it with the amp working versus not working, but I would expect it to make a very dramatic difference. My previous Ford had its amp unplugged when I got it and reception was dire - only the very strong signals could be heard. Once I had found the fault, reception was terrific.

Personally - I don't think the amp (or maybe the antenna) is as good as it could be. My last car used all of the rear window heater to provide an antenna and it worked superbly well.