RF interference on ADSL2+

I have just moved over to an LLU ADSL2+ connection and although I have a reasonable downstream attenuation (37db) and my line is stable with a 6.0db SNR, I cannot synch at more than 7mbps. Average synch speed on ADSL2+ for this kind of line is 10 - 12mbps.

Looking at the bit tone graph for my modem, there is severe roll-off above 880khz. There is a powerfull (200 kw ERP) MW transmitter less than 3 miles from my house. This transmits Radio 5 Live (900Khz), Talk sport (1100Khz) and Virgin Radio (1215khz).

Cabling into my premises consists of an old drop cable from the telegraph pole across the road into a BT80A RF2 junction box and then into the NTE5. The modem is plugged into an extension socket.

I suspect that the RF2 filter is causing the blocking of the higher ADSL2 and ADSL2+ frequencies, the tone graph exhibits the characteristics of an Inverse Chebyshev low-pass filter.

If I could engage OpenReach to remove the RF2 filter would this improve my ADSL2+ synch speed? The RF2 was originally fitted to block radio interference on the voice line, but the microfilter does this anyway.

The drop cable is about 35 years old now by my reckoning and is not grounded in the BT80A so presumably is not shielded. Are there any modern techniques and practices that can be deployed by OpenReach nowadays to prevent this kind of thing?

With the impending mass rollout of ADSL2+ as part of the 21CN initiative, I suspect that there will be many users who are going to be disappointed because they live near a MW radio transmitter.

The RF2 should either be removed or replace with an RF3 filter.
You will need to get ISP to report a fault to BT, maybe easier said than done.

Closer inspection shows that the RF filter installed at the moment is in fact a BT80B-RF3. There is no improvement if the RF3 is bypassed (allegedly).

Have you been able to plot your bits-per-tone response? There are some programs that can do this, such as RouterStats but it might be a pain to set up with your router. You can look at the numbers, but the curve is more immediate.

I have looked into this myself, I found certain tones were much lower than their neighbours. Where I am in Manchester tones around 340 (1440 - 1460 KHz) are virtually 0

You can map tones to radio frequencies

211 would be BBC 5 Live on 909 kHz
253 would be Talk Radio on 1089 kHz
282 would be Absolute (previously Virgin 1215 kHz)
338 would be Gold on 1458 kHz (in Manchester)

I find that there are response dips around all these frequencies on a bpt plot for my line.