Aerial Amplifier - Problem..

I used to have perfect reception until I changed stereos. I swapped out the aerial amp and still get the same problem. Radio works fine until the heated rear screen is switched on then all I get is crackling. I have tried this with and without power going to the amplifier and the problem remains. Also tried another stereo of the same make and same problem.
Could this be an earthing fault??

Also on the Coupe ISO power connector there is no Ign on/off just two permanent 12v feeds. Which one should I be using?? I always thought the thick red under the thick black but from standard ISO looms this is usually the IGN switched supply. So do I use the other permanent 12v feed or is it not up to the job (thinner wire IIRC).
I have an IGN wire connected so no worrieds on that part.

Cheers
Si

Si

This link shows a digramatic which will help identify the correct power leads and also the blue power ariel lead.
ISO Plugs

Does the make of stereo (which is?) have an output for a powered ariel, if not then connect the ariel via a fuse to the switched power lead.

I modded my coupe and took a feed from the ciggy lighter for switched power as I do not like having to turn off the radio every time I get out of the car.

Other things that can cause crackling when rear screen is on is a bad earch for the ariel amp.

JOhn

Thanks for that John,
The make is JVC - The clarion and panasonic before that had no problems - I am onto my second JVC headunit as the last stereo was an import and I always felt that may have had something to do with it!!

From that diagram the 12v main feed does come from the smaller wire in the coupe - In the coup in the IGN location is a big red wire (which is always on 12v) I have a feeling I swapped connections over so the last stereo used this as the permanent 12v and IGN from elsewhere (Does that make sense??)

Anyway the stereo does have a powered aerial output going to the correct place in the ISO plug that matches with the coupes wiring - so no probs there!!

I will take your advice and check the earth as thats the only thing yet to check. Probably quicker to run a new one in taking it away from the heated window.

Thanks
Si