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Turning on HD Fox T2 stops Freeview reception

HDRW

New Member
#1
I bought a 2nd-hand HD Fox T2 with a view to using it to record the odd programme to a USB stick, and to play recordings from my recently-acquired HDR Fox T2 (I'm a refugee Toppy owner! :)

I set up the HD in the living room and updated to the latest Custom firmware via USB stick. I tested everything including iPlayer, recording off air to a USB stick, and watching recorded programmes from the HDR via the LAN. So far so good...

I moved the HD to the bedroom, its intended destination, and wired everything up. It could not receive any TV signals. I had the antenna connected through the HD to the TV, and now the TV showed no signal either (was fine before). I removed the antenna link and plugged the antenna into the TV directly, and it still showed no signal. From what I could tell before the "No signal" screen popped up, it was showing a high "S" (signal?) level, but a very low Q (quality?) level. Turning the HD off resulted in the TV working properly, as before.

So I currently have the HD connected to the TV via HDMI, and to the mains, but to nothing else. With the HD in Standby, all is well. Turning the HD on causes total loss of reception on the TV.

As a Radio Amateur, this seems to me like massive interference, but why? It was fine on the living room setup, why would the bedroom be so bad?
The antenna feed to both locations is via a LabGear Distribution Amplifier, which has always performed faultlessly. The difference is that the antenna feed in the bedroom to the HD is direct from the LabGear, whereas in the living room it was daisy-chained through a Toppy and the HDR first.
The other difference is the HDMI connection is direct to the bedrom TV, but was via a multi-way HDMI switch in the living room.

Any ideas?

Incidentally, why the warning about not plugging-in the antenna with the mains plugged in? (I complied with this even though I don't understand it - it's not like the mains plug has the Earth connected, so I don't see a static-discharge or Earth-Loop issue being a problem).

Cheers,

Howard
G1BYY
 

MartinLiddle

Super Moderator
Staff member
#2
Have you tried swapping HDMI cables between bedroom and living room; interference from badly screened is a common cause of the symptoms you are reporting.
Incidentally, why the warning about not plugging-in the antenna with the mains plugged in?
I don't know for sure but if antenna power is turned on in the Humax settings then the aerial cable will be carrying 5V and there is a risk of shorting it (although I think there is short circuit protection).
 

Black Hole

May contain traces of nut
#3
I don't know for sure but if antenna power is turned on in the Humax settings then the aerial cable will be carrying 5V and there is a risk of shorting it (although I think there is short circuit protection).
Correct.

The interference problem smells like a classic case of leaky HDMI to me, although the description doesn't seem to fit. You can eliminate HDMI from the equation by using an analogue connection to the TV (SCART/RCA). The possibility of interference can be reduced by changing the HDMI video format (VFORMAT button) down to something with a lower clock frequency so that it isn't in the UHF band - if you have it set to 1080p try 1080i (you won't notice the difference in picture quality).
 
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MikeSh

Well-Known Member
#4
I don't know for sure but if antenna power is turned on in the Humax settings then the aerial cable will be carrying 5V and there is a risk of shorting it (although I think there is short circuit protection).
My hypothesis is that the protection is in the form of a slow start: On initial power up a limited supply is fed to the aerial and if that indicates a short it will shut off; otherwise full power is then applied. So applying a short after the box has done that check would be sub-optimal.
 
OP
OP
H

HDRW

New Member
#6
Bingo! Thanks chaps, changing the HDMI cable (for one that looked identical!) solved it - almost. The Hummy is now receiving perfectly and watching it on the TV via HDMI is fine,

However, the antenna signal isn't passing through to the TV's socket, so I need to find another Male-Female antenna cable (currently there's a gender changer then a male-male cable - one of these isn't working, obviously).

Incidentally, does the signal pass-through the HD when it's turned off?

prpr: Not sure what you're after - the cable from the antenna (in the loft) comes down to the LabGear distribution amp. in the bedroom, then a 2m flylead goes from that to the HD, then a female-famale gender changer on the HD's output socket to a 1m male-male flylead to the TV. As I said, the last link isn't working so needs changing.

Thanks muchly for the help, folks.

Cheers,
Howard
 

prpr

Well-Known Member
#8
Not sure what you're after - the cable from the antenna (in the loft) comes down to the LabGear distribution amp. in the bedroom, then a 2m flylead goes from that to the HD, then a female-famale gender changer on the HD's output socket to a 1m male-male flylead to the TV. As I said, the last link isn't working so needs changing.
I was trying to establish what the quality of said items was. It seems to me that you have (had) a leaky HDMI cable and RF cables which have no proper screening and are thus picking up all of that interference.
So what cable are these flyleads made from and likewise the downlead? I hope you are not going to say white/plastic/cheap, but I suspect you are.
And is the wallbox a decent make and reasonably well screened?
What else is the DA doing? Why don't you feed the HD and TV from it rather than daisy chaining through the HD? Or just get a (screened!) splitter.
 

Black Hole

May contain traces of nut
#9
Why don't you feed the HD and TV from it rather than daisy chaining through the HD?
Nowt wrong with doing that, it saves a second cable run or a splitter. Actually, I don't bother - the TV has an HDMI to the 'Fox and no aerial cable at all.