Radio Amplifier

[jamesh7216]

How reliable is the amplifier for the radio. My car is a 2003 Connoisseur Se and the radio reception is poor, i have checked and there is 12V supply to the amplifier, the heated rear screen works fine and there are no breaks in the wires, so i am thinking the amplifier may be faulty. Is there any way to check it, or is it a case of replacing it and see what happens?

[SD1too]

Originally Posted by jamesh7216

My car is a 2003 Connoisseur Se and the radio reception is poor...

Ahh, Ray, which radio do you have? Is it a Symphony or high line unit (with sat. nav. screen) by any chance?

Also is your car a saloon or tourer?

Simon

[jamesh7216]

Hi, The car is a saloon and the radio is the one with the satnav and TV screen

[Duotone]

The aerial amplifier is usually reliable but it is possible that it is faulty.

If you have 12v on the aerial amp connection then check the aerial plug connection to the radio unit in the boot area and to the aerial amp.




If it is the aerial amp that is faulty you could source on from one of the traders/breakers on here.

Dave T

[SD1too]

Originally Posted by jamesh7216

My car is a 2003 Connoisseur Se and the radio reception is poor .. i am thinking the amplifier may be faulty.

Originally Posted by jamesh7216

The car is a saloon and the radio is the one with the satnav and TV screen

I think I know what the problem is Ray.

Your highline radio has a system called 'diversity' which switches in additional aerial elements when the signal strength is weak. To save money, from VIN 240702 (said to be 10th December 2001) the rear screens were standardised and the simpler design was fitted to all cars. Unfortunately this screen does not have the three FM elements required for the diversity system to work properly.
At the same time, MG Rover fitted a simpler 'amplifier' which was never designed to work with the diversity system, and this is the module which Duotone has illustrated in his reply. The diversity version is about three times its length.

So the result of all this is that when radio reception is weak, your radio calls for additional aerial elements to rake in more signal, but the module is not there to achieve the switching. Even if it was, your rear screen only has one FM element so there is nothing to switch to!

Simon

[murphyv310]

Originally Posted by SD1too

I think I know what the problem is Ray.

Your highline radio has a system called 'diversity' which switches in additional aerial elements when the signal strength is weak. To save money, from VIN 240702 (said to be 10th December 2001) the rear screens were standardised and the simpler design was fitted to all cars. Unfortunately this screen does not have the three FM elements required for the diversity system to work properly.
At the same time, MG Rover fitted a simpler 'amplifier' which was never designed to work with the diversity system, and this is the module which Duotone has illustrated in his reply. The diversity version is about three times its length.

So the result of all this is that when radio reception is weak, your radio calls for additional aerial elements to rake in more signal, but the module is not there to achieve the switching. Even if it was, your rear screen only has one FM element so there is nothing to switch to!

Simon

Hi.
That seems odd! I for the life of me can't think that the Diversity system works like that. Diversity systems work by phasing up signals from two separate signal sources. This will be the reason for the larger amp but surely there is only one RF feed to the receiver whether Symphony, Hi'line or Harmony in the earlier cars.
My Club SE has the larger amp but only one coax to the set.

[SD1too]

As explained Trevor, the module (or 'amplifer') performs the switching so yes, there is only one RF coax cable to the receiver. There is a thinner feedback cable from receiver to module. If you Google 'diversity' you'll probably find a better explanation than mine.

Simon

[murphyv310]

Hi Simon.
Yes the thinner lead will control the amp with AGC, they should be always phased up though as I believe this is a "combining" system. With the thin lead out, the amp should run at maximum gain.

Regarding the OP's problem it could well be the tuner itself. I'd try a wire aerial of around a meter long fed to the centre pin on an aerial plug and hold the wire out of the boot, this should pick up stations with ease and discount the amp/aerial or place the tuner under suspicion, they can and do suffer with dampness.

[SD1too]

Originally Posted by murphyv310

Yes the thinner lead will control the amp with AGC ..

No, the 'diversity' system is not the same as automatic gain control.

I am pretty confident that the rear screen/module combination will be the OP's problem. I've seen, and heard, it before on a couple of cars.

... of around a meter long ...

American spellings Trevor? Tut tut ...

Simon

[murphyv310]

Originally Posted by SD1too

No, the 'diversity' system is not the same as automatic gain control.

Simon

I didn't say it was. You need AGC to control the amp, it depends on what type of diversity system it uses, there are many different types and all work in a different way. At a well educated guess this will be a combining system, phase errors will be cancelled out in the amp but it will need AGC from the tuner to reduce gain as necessary.
AGC in this system is simple RF AGC, just like in a decent radio (communications sets etc) that reduces IF overload.
The aerial amp is designed to feed a stronger signal to the radio to reduce noise, better to feed a strong signal to a set than a weak one full of digital rubbish from ECU's etc that can give hash especially on AM.