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Picture missed off
Wilson
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The power connections are built into the fibre cable you don’t need power at the lnb just like a conventional universal lnb.
Graham,
Thanks for that. On my estimation the total cost of the LNB, the optical to copper box and 50M of cable come to £370. I can buy 50M of WF100 twin 7mm shotgun cable for around £55. I really need to replace the plastic conduit anyway as the wild boars have dug it up a few times and it is quite ‘repaired’. Conduit is dead cheap at around £8 for 50M. I doubt if I would be able to pull the WF100 cable through the old conduit. It is always easier to thread the cable through before you bury it. Then I need another lightning protector at €90. Ignoring the labour element, you can see that there is quite a difference in cost.
Dishes being struck by lightning are very rare. The loss adjuster who visited said it was the first one he has ever seen. I have hammered a large steel spike into the ground at the dish and earthed the dish, hoping that most of the current will go this way rather than down the aerial wire (see photos of LNB and aerial wire). The fixings to the rock face are plastic Rawlplugs with 6″ coach screws. When it got hit, two of these 6″ screws were fired 25 feet across the garden. If my dish was struck again, I assume that it would kill the optical LNB, if I had fitted one at another £159 against £27 for a twin Invacom LNB. The gas earth diverter valves are rated for 5 events, before they need replacing.
I think you can see where I am coming from. Your suggestion is a very clever one but I think the economics argue in favour of a traditional copper wired LNB.
On a totally different subject, has anyone on the Forum modified an HD or HDR box to have a Coax S/PDIF output in place of the optical. In theory, this is always better as optical is limited to 44.1 KHz. Also you are taking two links out of the audio chain, the digital to optical converter and the optical to digital converter, which again must degrade the signal, add noise, etc.
Wilson
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Wow, yes I did initially say probably a bit late now. Were you starting from scratch the economics make a lot more sense
I offer the following thought that you might like to consider.
For 40yrs I was a planning engineer with National Grid. Next time you are near enough have a close look at a 275kV or 400kV overhead line. These carry two circuits with the phase conductors vertically spaced either side of the tower. At the peak of the tower is a smaller aerial earth conductor which is bonded to each tower. The primary purpose of this is to create a cone of protection from direct lightning strikes on the main phase conductors. These days though the earth conductor encloses a fibre bundle to create a high speed data connection.
It might be possible to protect the dish in a similar way with a seperately bonded conductor over the dish.
A lightning conductor mounted higher up the rock face might be worth considering. The sharp points on these in the prescence of a strong potential difference create a conducting ionised air path and can in fact discharge charged clouds as well as providing a more attractive target.
My hdr in fact has a optical to coax s/pdif converter due to the distance of my AV amp from the hdr (about 10M) at this distance attenuation of the optical signals can be a problem due to the low power led light source used. As you would expect being digital it has no effect on sound quality. There’s loads of these on flea-bay
Example
Graham,
I use one of those boxes in the UK, with the same problem as you. The optical signal from my Apple Airport Express was too weak to wake up the Beresford DAC, which is about 6 meters away and I had to put in one of the opt-coax boxes.
I really have an itchy soldering iron hand and thought of delving into the Humax to see if I could strip out the audio signal before it hit the optical output generator. I suspect the voltage is a bit on the low side (coax needs 0.5 to 1.0 V peak to peak to work well at a DAC). I might need to put in a little NME 49720 op-amp to boost the signal (handles up to 55 Mhz so the 96 KHz would not be an issue). I would then probably put a BNC connector on the outside.
Wilson
I have said thank you to Barry and Humax privately for solving my problem but I think the help that Barry gave me and the very quick response of Humax with new FW deserves a public acknowledgement, so thank again both guys.
Wilson
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