Humax HDR-FOX T2 Problems when recording

[notapom]

I just thought I'd update something I've noticed regarding my issue.

So if I watch a channel on one mux and make an instant recording then switch to another mux to watch or make another instant recording, the signal quality drops to non viewable levels and the recording would mirror this but if I am viewing one mux and record a live broadcast from another mux via the epg OR if a scheduled recording begins, then the signal quality drop does not occur.

It seems only to an issue to view a second mux not to record it in the background

 

[Black Hole]

Without reading back... have you checked the health of your HDD and file system?

 

[notapom]

Without reading back... have you checked the health of your HDD and file system?

I think I've found the source of the problem, currently troubleshooting to confirm. Will update later

 

[notapom]

So yeah it was the aerial set up causing the issue even though both tuners displayed good signal strength and quality.

I have 2 aerials, 1 for Freeview, 1 for Saorview combined to come down 1 cable. Obviously the Saorview aerial picks up the local Freeview signals, I am aware that there could be issues with signals cancelling each other out but i had never had problems and this setup has been working for years until recently.

One of the Freeview muxes completely disappeared for about a week before I had a chance to investigate. The signals on that particular mux were cancelling each other out as when I disconnected the Saorview aerial, the missing mux would reappear. When I disconnected the Freeview aerial, I realised I still received weak Freeview signals from the Saorview aerial so I positioned it in a way that I was receiving good signal strength from both transmitters

10% signal loss on SV, now 40-45% signal strength, 5% loss on FV, now 55-60% and 0% signal quality loss on both, still 100%.

This for some reason was causing the issue as when I pointed the aerial to the Freeview transmitter and checked the Humax, I was not getting the tuner 2 issue anymore.

I've since put the setup back to its original configuration and everything is well. 55% on SV, and 65% on FV, 100% quality.

No idea why this was happening and I didn't think the check the aerial due to the new setup having adequate signal, and every TV and Freeview box was working fine apart from the Humax.

 

[prpr]

I expect cancellation will be cable length dependent to the equipment, so one unit could work and another not, depending on the relative phases at any particular point.

 

[notapom]

I expect cancellation will be cable length dependent to the equipment, so one unit could work and another not, depending on the relative phases at any particular point.

I'll be honest, I'm not sure I understand you. Too technical for me.

I did read when setting the aerials up that the cables from each aerial should be the same length before being combined so that the wavelengths (Not sure of correct term) of the Freeview signals received on the Saorview aerial match the wavelength of the signal received on the Freeview aerial.

This sounds similar to what you mention regarding the cable length?

There had been no change in the set-up when the cancellation occured so unsure why it happened and why it works now it has been put back as it was.

You've given me some information to look up to gain a better understanding on the subject, so thanks for that

 

[MikeSh]

There had been no change in the set-up when the cancellation occured so unsure why it happened and why it works now it has been put back as it was.

Could have been a connection that started to get a higher resistance which could affect reflections within the cable(s). You may have accidentally fixed that.

 

[notapom]

Could have been a connection that started to get a higher resistance which could affect reflections within the cable(s). You may have accidentally fixed that.

You know what, you might be on to something there.

I did fiddle with the connections when troubleshooting last time, they all looked fine though so I didn't suspect them being the problem.

I did replace an f-connector from the unused aerial today as it was missing it's f-connector, I must have removed it when taking the aerial out of use.

 

[Rodders53]

Ideally the antennas should be combined using a filter to prevent this sort of thing happening... But they are now rare / difficult to find that suit the two transmitters: unless this https://www.aerialsandtv.com/product/diplexer-channel-38-uhf-uhf would work.

Two aerials wideband combined will exhibit unpredictably and reflections from the ground, tree foliage and/or water (e.g. tidal sea paths) can give variability, too.

But a cable with no connection to an antenna will be even more unpredictable.

 

[notapom]

Ideally the antennas should be combined using a filter to prevent this sort of thing happening... But they are now rare / difficult to find that suit the two transmitters: unless this https://www.aerialsandtv.com/product/diplexer-channel-38-uhf-uhf would work.

Nah I diplexer won't work for me as the channels are interlaced. Freeview 22, 25, 28 and Saorview 23 and 26. I didn't want a switch so I tried a combiner which worked fine.

But a cable with no connection to an antenna will be even more unpredictable.

I think you have misunderstood, maybe I wasn't clear. When I took one of the aerials out of use, I must have removed the f-connector on it's cable so when I went to use it again today, I realised it no longer had one.

There was never a point when I thought there was an aerial connected when it wasn't.

I may be thick but I'm not that thick!

 

[Black Hole]

I'll be honest, I'm not sure I understand you. Too technical for me.

Two aerials picking up the same signal, which has a wavelength of (say) 15" in air and (maybe) 8" in a cable. If the signal from aerial A has to travel and extra half wavelength (or one and a half, or two and a half...) total between the physical offset of the aerials and the different cable length where they combine, there will be destructive interference (the two signals end up subtracting). Signals with different wavelengths will be affected differently, some might add up rather than subtract (if there's a whole number of wavelengths difference).

By the same token, every junction in the signal path is an opportunity for some of the signal to bounce back, which can set up a resonance (rather like the way a laser works). According to the distance between the junctions, some wavelengths get reinforced and others notched out.

This principle can be used to notch out a very specific frequency, by adding a stub of cable and trimming the length down until it has the desired effect.

 

[notapom]

Two aerials picking up the same signal, which has a wavelength of (say) 15" in air and (maybe) 8" in a cable. If the signal from aerial A has to travel and extra half wavelength (or one and a half, or two and a half...) total between the physical offset of the aerials and the different cable length where they combine, there will be destructive interference

Right, gotcha. I had read this when researching and did make sure that the cables were the same length before being combined but that's it, the rest was winged with my novice level of understanding with decent results until recently.

Still unsure why any of this would cause the 2nd tuner issue with the Humax especially when the issue only occured when using a single aerial and when only viewing and not recording

Everything is back in working order now anyway so happy days! Was thinking of selling the Humax as faulty, close shave!

 

[Black Hole]

Still unsure why any of this would cause the 2nd tuner issue

I agree. RF is like a black art, but even so this seems to defy reason so I suspect there is another problem which has only gone away temporarily and is fooling you into a false sense of security.

Answer the previous question:

Without reading back... have you checked the health of your HDD and file system?

 

[notapom]

I agree. RF is like a black art, but even so this seems to defy reason so I suspect there is another problem which has only gone away temporarily and is fooling you into a false sense of security.

Answer the previous question:

Performed HDD test on the Humax and ran fix-disk. Both passed

RF is like a black art, but even so this seems to defy reason so I suspect there is another problem which has only gone away temporarily and is fooling you into a false sense of security.

Sounds ominous