2003 V70 poor radio reception

[aland]

This is similar to the other thread about S60 radio reception, but for a V70 - so slightly different.

- 2004 MY / 53 reg V70R
- Aftermarket radio*
- Otherwise original**

* The radio reception was poor before the radio was replaced, so I don't believe this is a factor.
** Well apart from a SS exhaust, which shouldn't matter.

I'm aware that USB chargers etc can cause issues in these cars, this issue remains with that stuff unplugged.
I've changed over the blue (IIRC) amp mounted in the top left of the boot area for another I had, no improvement.
The aftermarket radio also has DAB - that is also poor, but I put that down to the DAB antenna - but who knows.
I've tried pulling and re-fitteing the 'AUDIO' fuses in the front fusebox as suggested in the other thread (although they were fuse 16 & 17 rather than 10), but no change.

Soooo - where else should I check?
I'm aware of the bumper antenna as well as the window one, but I don't think the aftermarket radio with single antenna input would use it.

I'm currently tempted to fit a roof-mount combo FM/DAB antenna, but put off by the requirement to drill a hole in the roof!

[SwissXC90]

What I used to do when I was installing and repairing car radios to diagnose bad antennas:

1. Locate a weak station on the radio.
2. Listen to it and take note of the performance (amount of hiss and noise, ability to decode stereo if on FM, ability to decode RDS if it has RDS)
3. Disconnect antenna from radio
4. Insert a 1m to 2m length of wire (any old wire will do, as long as it is insulated) into the center conductor of the antenna socket, taking car not to short to the radio body.
5. This wire becomes a new, simple, passive antenna.
6. Does the reception suddenly improve? If it DOES, then you have confirmed the vehicle antenna is not very good. If it does NOT, then you have confirmed the vehicle antenna is about as good as your piece of wire, and the fault must be in the radio.

NOTE THAT modern vehicle antennas have antenna amplifiers mounted right at the antenna. The amps have to be powered. Many use phantom power through the center conductor of the antenna cable.
What does yours use? A separate supply? or phantom power? Does it have any power at all?

Check also the grounding of the antenna amplifier, it needs to be a good clean ground to ensure best reception.

And your car will likely have a diversity antenna system, so check both main and sub antenna systems.

And the symptoms and fixes are different for AM vs FM. You need to state if you have an AM, FM or both problem.