I have had a Humax HDR Fox T2 for several years without any problems.
Earlier this year I started to get intermittent signal loss on all channels on COM7 and COM8 (most noticeable on BBC News HD and BBC Four HD). All the channels on other multiplexors remain perfect. Assuming that this was an aerial fault I decided to upgrade my old aerial to a more modern one with a mast head pre-amplifier (to reject 4G-800LTE etc.).
Alas this provided no improvement with COM7 and COM8 (although I do get a stronger signal on all channels). I still get severe interference and/or complete loss of picture for several minutes typically every 15 to 30 minutes. There does not seem to be a pattern to the timing or duration of the signal loss. The signal strength and signal quality (as shown by the Humax on the live TV information at the bottom right) is 8/10 when everything is good and 8/0 when there is signal loss.
My television (a Samsung UE55H6400) has an aerial feed thru via my Humax and has no problems with COM7 and COM8 even when the Humax says “no signal”. I can reliably switch backwards and forwards between the TV and the Humax (both on say BBC News HD) and get a perfect picture on the TV and “no signal” on the Humax.
Transmitter: My local transmitter is Oxford, using channels 41,44,47,29,37,31 and channels 55,56 for COM7 & COM8 respectively. The transmitter is 36km away. My alternative transmitter is Sandy Heath (43km away) and this also uses 55,56 on COM7 & COM8. I do not see any of the Sandy Heath channels after a re-tune. Oxford is on a Bearing of 219 and Sandy Heath is on 74.
Aerial: My aerial is a “V10-13L 13 element Yagi aerial Ch21-60 4G-800", my mast head pre-amp is a “V20-27T 1in1out variable masthead 12-27dB, Group T, CH: 21-60".
Signal Strength/Quality: My Humax gives the following information under “Tuned Multiplex Information.”
29 538.0 MHz 90% 100% Oxon & Bucks COM4/SDN
31 554.0 MHz 90% 100% Oxon & Bucks COM6/ARQ
37 602.0 MHz 86% 100% Oxon & Bucks COM5/ARQ
41 634.0 MHz 96% 100% Oxon & Bucks PSB1/BBC
44 658.0 MHz 96% 100% Oxon & Bucks PSB2/D3&4
47 682.0 MHz 96% 100% Oxon & Bucks PSB3/BBC
55 746.0 MHz 85% 100% Com78 National COM7/ARQ
56 754.0 MHz 84% 100% Com78 National COM8/ARQ
Signal Attenuation: Because my signal strength is so good (and having read replies to similar questions on this Forum) I have tried attenuating my signal between 3 dB and 30 dB. Whilst this produces the expected loss of signal strength it does not cure my problem.
HDMI Cables: I have tried several different high quality HDMI cables and all the HDMI sockets on my TV. My HDMI cable is not close to my Humax aerial-in cable and the two cables never run together.
Mains power: I have tried using an external mains filter on the Humax, without effect.
Humax Tuner: In order to see if the problem was specific to one (of the two) tuners in my Humax I have tried recording a non-COM7 COM8 channel whilst simultaneously watching a COM7 channel. With the same result.
Humax Firmware: Custom firmware version: 3.12 (build 3965), Humax Version: 1.03.12 (kernel HDR_CFW_3.12), Loader Version: a7.30.
Other equipment: I have powered down and/or removed all other electronic equipment within several metres of my Humax/TV.
If anybody has any suggestions what to do next they would be greatly appreciated.