Have you seen this which is on the thread "DAB on the move"?
"There is no DC connection between the GSM centre connection and the stubby, so buzzing it with a DVM shows an open circuit. This confused me initially. But it does connect (in my case anyway) at the radio frequencies used by DAB (around 220MHz). You can do a quick and dirty test on the FM band by changing the stubby for a normal mast, and connecting the inner connection of the GSM cable to the centre connection of the radio's aerial connector with a short piece of wire - if you get reasonable FM reception then you will almost certainly be OK for DAB."
I'm not after DAB just a decent signal for LW to listen to Test Matcch Special and hope to try this experiment after Christmas, unless of course you come up with something else after your trials.
Well I have sort of seen that post looking for previous problems/solutions for the FM radio reception. I have only just read your post but I have had an experiment this morning....
I think based on previous reports the GSM aerial will work for DAB. I do infact have a DAB aerial on my front screen at the mo, but as I am looking at adding a new roof aerial I am not worried about swapping it at the mo (unless I give up as its to hard work!).
This morning I cut the SMA connector off the car and wired on an ISO connector from a Mark 1 156.... Now the moment of truth....
I am going to use a scale:
The control being a Honda Civic with a very good signal on KISS 100 FM in Gravesend.
(These are an estimate btw)
Honda Civic 90% signal
My facelift 156 with rear screen aerial 50% signal (has the original Alfa signal booster)
My facelift 156 using GSM aerial with no booster 10-20% signal.
My facelift with the aerial disconnected 0% signal
So it shows the GSM aerial does something, but it isn't as good as the rear screen with booster. How much could the GSM aerial be boosted with a inline signal booster? Who knows, but I am not sure that would work on a GSM aerial anyway.
I am now thinking of getting a later aerial/amp from a 156/GT or from a 147 to test that next.
Merry Christmas all,