70M : SH3 Power levels & T3 errors

[A17]

I'm on VM broadband using the SuperHub 3.
From what I've read online the downstream power levels should be close to 0dbmv and if I remove an 8db forward path attenuator I can get much closer to it. I have been using it without the attenuator recently but the connection will randomly disconnect for a few hours unless I manually power cycle the hub, and there seems to be quite a lot of t3 timeout errors on the hub.
Here are the stats WITH the attenuator fitted:

Downstream bonded channels
Channel
Frequency(Hz)
Power(dBmV)
SNR(dB)
Modulation
Channel ID
1
299000000
-8.2
38.6
256 qam
55
2
323000000
-8.7
37.6
256 qam
58
3
315000000
-8.9
38.6
256 qam
57
4
307000000
-8.7
38.6
256 qam
56
5
291000000
-7.9
38.6
256 qam
54
6
283000000
-7.4
38.6
256 qam
53
7
275000000
-7
38.9
256 qam
52
8
267000000
-6.7
38.9
256 qam
51

Upstream bonded channels
Channel ID
Frequency(Hz)
Mode
Power(dBmV)
Modulation
Channel Bandwidth(Hz)
Symbol Rate (ksps)
2
39400000
ATDMA
44.8
16 qam
6400000
5120
4
25800000
ATDMA
44.8
16 qam
6400000
5120
3
32600000
ATDMA
44.8
16 qam
6400000
5120
1
46200000
ATDMA
44.8
16 qam
6400000
5120

Also, without the attenuator fitted I noticed that my downstream power levels randomly spike from around 0 to +7 at night and will be back to around 0 by the morning. Is this normal?
These T3 errors also showed on my old SH1 but the connection would only be lost when the DHCP expired.

All help is appreciated.

[heero_yuy]

Hi and welcome to the forum.

I suspect that there is a bad connection or intermittent bit of kit. When the SH was installed the tech fitted the 8db FPA to make the signal level correct. The sudden change of level overnight by 7db, possibly back to that which was present at installation time, is not correct.

Also your upstream channels are on QAM16 rather than QAM64 indicating a possible SNR (noise) problem which again could be a bad connection allowing external noise to enter the system as possibly evidenced by the T3 errors.

If you've checked all your internal cables for security you probably need a tech to visit and investigate.

[A17]

Many thanks for the speedy reply heero_yuy.
The last time a tech was here was over 5 years ago when they installed a SH1, since then I did the self install of a SH3.
Now you mention it - I do remember the upload being QAM64 years ago but has remained at 16 since.
Will contact VM through their own forum, can't be bothered to battle with over the phone support.
Once again, thanks!

[jb66]

For now removing the attenuator should help