View Full Version : DIY Power inserter
I understand that there is still an issue with unicable and recordings. The solution seems to be to keep the physical tuner, say Tuner A, powered on.
Is there a simple "cable power injector" solution? A simple DIY one as shown here - http://www.satcure.co.uk/tech/dc_inserter.htm
I'm assuming that the LNB is to the left. Power could be simply taken from the 12v supply to the receiver. Then whenever power to the receiver is on, the LNB is also getting power.
And I now think that the splitter I bought is actually a power inserter:
https://www.toolstation.com/proception-wideband-tv-satellite-splitter/p66100
DC goes in at the top, right hand bottom to LNB and left hand bottom to receiver.
Just checked the so called splitter with a multimeter. And indeed the power pass does let DC to go along the dotted line. And nothing the other way. So bottom right to LNB and bottom left to receiver.
And the receiver only appears to have 13v on the Tuner A F male plug?? Tuner B F male plug is 0v??
I think I have worked out the following:
Jess is a specific design and make of Unicable and is similar to Unicable 1 and 2. Made by Jultec. https://wiki.openpli.org/Unicable_/_Jess
Unicable LNB just requires 12-13v at around 350ma, so approx 4 watts. Power to GB receiver is 12v. So can be taken from power supply lead to the power INSERTER. No need for a 240v adapter.
Legacy LNB switches 2 voltages, around 14v and 18v. Done by receiver and takes less power.
I have 2 cables from my dish at home, so an LNB with Unicable 2 and a Legacy cable would work - I think??
Anyone heard of Maclean TV Systems Unicable 2 LNB??
I got the sky power inserter today, fitted it and thought that's sorted it, i'm afraid not, tried it before my splitter then after it, still the same problem.
That is not good to hear.
Think I'll try the DIY solution at http://www.satcure.co.uk/tech/dc_inserter.htm
BrianTheTechieSnail
16-07-20, 14:55
That is not good to hear.
Think I'll try the DIY solution at http://www.satcure.co.uk/tech/dc_inserter.htm
That doesn't seem to mention any inductor to stop you losing the RF through the source of DC!
A capacitor to stop the inserted power going back towards the receiver might also be a good idea.
Similarly, further down, the one shown as a way of measuring the current doesn't show any capacitor to complete the circuit at RF frequencies.
However wrote this page didn't really seem to know what they were doing!
There's no direct DC connection to the plug end, Brian. The RF signal is capacitively coupled to the plug as described in the photos. It's all a bit "Heath Robinson-ish" but should work. Martin Pickering ran that website and shop for years and provided some excellent technical guides on electronics, aerials, cables and satellite connectivity. He retired to Crete some years ago. Still provides technical advice on Quora. Bit of an old curmudgeon and grammar nazi, but maybe that's why I always liked him!
BrianTheTechieSnail
17-07-20, 23:46
There's no direct DC connection to the plug end, Brian. The RF signal is capacitively coupled to the plug as described in the photos. It's all a bit "Heath Robinson-ish" but should work. Martin Pickering ran that website and shop for years and provided some excellent technical guides on electronics, aerials, cables and satellite connectivity. He retired to Crete some years ago. Still provides technical advice on Quora. Bit of an old curmudgeon and grammar nazi, but maybe that's why I always liked him!
Ah. Designed to be buildable even if you don't have access to electronic components I guess.
Also no DC isolation if both your receiver and your dish are earthed. But that's relatively unlikely I guess.
Still nothing to stop the RF going out (or in) via the red and blue wires though.
Ah. Designed to be buildable even if you don't have access to electronic components I guess.
Also no DC isolation if both your receiver and your dish are earthed. But that's relatively unlikely I guess.
Still nothing to stop the RF going out (or in) via the red and blue wires though.I really don't understand what you are worried about. Are you a theory man looking for an inconsequential fault with this solution? If you are really worried that IF (not RF) might be leaking up the DC feed put a ferrite inline.
BrianTheTechieSnail
18-07-20, 18:20
I really don't understand what you are worried about. Are you a theory man looking for an inconsequential fault with this solution? If you are really worried that IF (not RF) might be leaking up the DC feed put a ferrite inline.
When I tried to measure the current with a similar heath robinson solution I could not make it work. The receiver kept cutting off the power saying there was no signal.
I must admit I don't know if the problem was loss of signal or loss of screening meaning RF hash was getting in.
Just trying to point out that in my experience you will get nowhere with such a bodge method.
When I tried to measure the current with a similar heath robinson solution I could not make it work. The receiver kept cutting off the power saying there was no signal.
I must admit I don't know if the problem was loss of signal or loss of screening meaning RF hash was getting in.
Just trying to point out that in my experience you will get nowhere with such a bodge method.Sorry I thought you were talking about a proper solution such as the inserter sold by WoS.
Just tried a GigaBlue Unicable LNB - 24 SCR, 2 Legacy.
Signal strengths - Unicable SNR 98/99%, AGC 8%, 16.0dB. Legacy SNR 99% AGC 97% 16.0 dB. Went through the Tuner set up correctly - I think. Signal strengths are better than elderly Universal LNB. So interesting that Unicable AGC is 8% and Legacy 97%.
Unicable is complete rubbish with continual "Tune Failed". Legacy is fine.
So tried power injection with 11.9v at the LNB. No signal at all?? Odd, so I'll bump up the voltage to 20v and see if that makes a difference.
Otherwise, grateful for any pointers??
Just tried a GigaBlue Unicable LNB - 24 SCR, 2 Legacy.
Signal strengths - Unicable SNR 98/99%, AGC 8%, 16.0dB. Legacy SNR 99% AGC 97% 16.0 dB. Went through the Tuner set up correctly - I think. Signal strengths are better than elderly Universal LNB. So interesting that Unicable AGC is 8% and Legacy 97%.
Unicable is complete rubbish with continual "Tune Failed". Legacy is fine.
So tried power injection with 11.9v at the LNB. No signal at all?? Odd, so I'll bump up the voltage to 20v and see if that makes a difference.
Otherwise, grateful for any pointers??
Post tuner setup
I'll have another go tomorrow. Back on Legacy. Test Match Special!!
But went through each FBC tuner - Cable to A, loop through to B, B External power Yes, Different band for each tuner.
Can also try splitting cable to A and B with 3 FB on each.
Seems that Vu+ might be the way ahead after all.
Just tried a GigaBlue Unicable LNB - 24 SCR, 2 Legacy.
Signal strengths - Unicable SNR 98/99%, AGC 8%, 16.0dB. Legacy SNR 99% AGC 97% 16.0 dB. Went through the Tuner set up correctly - I think. Signal strengths are better than elderly Universal LNB. So interesting that Unicable AGC is 8% and Legacy 97%.
Unicable is complete rubbish with continual "Tune Failed". Legacy is fine.
So tried power injection with 11.9v at the LNB. No signal at all?? Odd, so I'll bump up the voltage to 20v and see if that makes a difference.
Otherwise, grateful for any pointers??
Why not just use a proper purpose made power inserter? https://www.world-of-satellite.co.uk/satellite-and-terrestrial/universal-and-unicable-lnb/unicable-universal-lnb-power-inserters/gt-sat-gt-pi1-unicable-universal-lnb-power-inserter
Just tried a GigaBlue Unicable LNB - 24 SCR, 2 Legacy.
Signal strengths - Unicable SNR 98/99%, AGC 8%, 16.0dB. Legacy SNR 99% AGC 97% 16.0 dB. Went through the Tuner set up correctly - I think. Signal strengths are better than elderly Universal LNB. So interesting that Unicable AGC is 8% and Legacy 97%.
Unicable is complete rubbish with continual "Tune Failed". Legacy is fine.
So tried power injection with 11.9v at the LNB. No signal at all?? Odd, so I'll bump up the voltage to 20v and see if that makes a difference.
Otherwise, grateful for any pointers??
Inserters with matching power supplies from other manufactures of unicable II LNBs suggest a 19V supply voltage.
Into which downlead are you injecting the power? It should be the unicable output and not the legacy.
When injecting power via an inserter is there a facility to stop the box also providing power to the LNB - the two power sources could be fighting each other?
How much current can your external power module supply - the spec suggests 300mA for the unicable side of the LNB ?
Also, if you are using a power pass splitter it should be diode protected so voltage from one STB cannot arrive at the aerial socket of another that shares the same LNB. i.e. the voltage can only flow from the STB to the LNB but not in the opposite direction... and the STB itself should also have diode protection at the socket to prevent external voltage from entering it.
I assume that the STBs are already internally diode protected if by design they all can produce the unicable power to common down lead. It makes sense that the STBs all produce power because one or more boxes connected to a common down-lead (via splitters) could be switched off and the LNB still has to get its power from one of the STBs still switched on. The individual STBs don't know when someone is going to switch off another box on the cable.
The important part of your statement is that the power inserter must also have diode blocking on the power supply input because without a diode a power supply with a low source impedance would instantly drag down the voltage output from any STB if the external power supply was set to a voltage below what the STB would output itself. By design I would expect the STB to also be protected by current limiting its own output to what it sees as a virtual short circuit.
One question for my own education
In a unicable tuner mode do the STB boxes with multiple satellite input sockets produce the voltage on all these socket inputs all the time when the box is switched on or only when a tuner (or tuners connected to the socket by various internal means) is required for watching/recording?
With regards the DIY hacked power inserter mentioned elsewhere in this thread. It was not put forward on Satcure site as an alternative supply for unicable LNBs but more for getting power for other purposes such as providing power to a remote control extender (magic eye) or a head end amplifier on a terrestrial aerial system where the typically 5V from the terrestrial box could be switched off and 12V supplied from an external source . Note that the DIY solution doesn’t show F plugs but Belling Lee type connectors used for terrestrial TV. A hack designed for one purpose doesn’t necessarily work for different systems.
Post tuner setup
Right had a another fiddle.
Satcure DIY DC power injector and 19.5v at Gigablue Unicable 2 LNB. When I last looked WoS didn't have any injectors but see them now in stock.
SNR 100%, AGC 7% and 16.4 dB. Don't think I can get better than that.
Tuner A
60453
Tuner B to H as H. Each Tuner has own Channel, starting with Channel 1 for Tuner A to 8 for H.
60452
Slight blank screen on Channel change.
Tried Tuner B equal to A, but CrossEPG wouldn't download - "CrossEPG error. Timeout for Tuner lock".
Now set 8 recordings and get picture break up and "Tune fail".
Perhaps as suggested in other posts, I should split signal to Tuner A and B and feed 3 FBC off each??
Now set 8 recordings and get picture break up and "Tune fail".
Could this now be down to the quality of the cables you are using or the integrity of the cable now that you have cut into it to hack a power source? With unicable you asking more of the cable than with a TV aerial or a traditional LNB. Are you using a CT100/WF100 type cable with a full copper screen + screen braiding?
A hack into the cable may mean its no longer got a characteristic 75 ohm impedance and you are now getting reflections.
https://en.wikipedia.org/wiki/Signal_reflection
https://www.youtube.com/watch?v=zrDxSM91Jcg
Cable is OK - copper braid, alu wrap, air core. Would have thought VSWR could be incorporated into software?? - my marine AIS receiver has a VSWR read out.
Now split the cable after the power injector to feed Tuner A and B - might as well use both of them as I've paid for them!! And 3 FBC tuners off each. Much better. SNR 99%, AGC 5% and 16 dB on both tuners.
8 channels merrily recording.
BrianTheTechieSnail
23-07-20, 15:56
Cable is OK - copper braid, alu wrap, air core. Would have thought VSWR could be incorporated into software?? - my marine AIS receiver has a VSWR read out.
I don't see how it can unless it transmits as well as receiving.
Well fitted the V5-033 device with 19.5v DC going up to the LNB, green LED lit, and other end to the receiver.
https://vision-products.co.uk/switchable-direction-dc-inserter-line-power-tap/
Nothing in any combination of cables to tuners etc.
I think I'm using it correctly?? - but someone may know better??
Whereas homemade device is perfect - 100%, AGC 4%, BER 0 and 16.0dB on both tuners
I got the sky power inserter today, fitted it and thought that's sorted it, i'm afraid not, tried it before my splitter then after it, still the same problem.
After some digging around, and as I understand it, it is not clear if the Sky 161 is to EN50494/EN50607 standards which passes 22kHz signals from the receiver to the LNB, including Unicable II LNB to set the bands. The power inserter I bought, which doesn't work, doesn't mention EN50494/EN50607 in it specifications. Neither does the GT-Sat GTPI1 Unicable / Universal LNB Power Inserter with 15V DC PSU as sold by World of Satellite.
These units have a typical frequency range of 5 - 2200 mHz.
Perhaps a real techie can comment??
The only power inserter that I have found and which mentions EN50494/EN50607 is the Inverto unit - https://www.inverto.tv/accessories/326/unicable-ii-power-inserter-5-2400mhz
Or a homemade one which lacks all electronic wizardry that stops the 22kHz signals, and so it works!!
A right minefield!!
BrianTheTechieSnail
29-07-20, 16:23
After some digging around, and as I understand it, it is not clear if the Sky 161 is to EN50494/EN50607 standards which passes 22kHz signals from the receiver to the LNB, including Unicable II LNB to set the bands. The power inserter I bought, which doesn't work, doesn't mention EN50494/EN50607 in it specifications. Neither does the GT-Sat GTPI1 Unicable / Universal LNB Power Inserter with 15V DC PSU as sold by World of Satellite.
These units have a typical frequency range of 5 - 2200 mHz.
Perhaps a real techie can comment??
The only power inserter that I have found and which mentions EN50494/EN50607 is the Inverto unit - https://www.inverto.tv/accessories/326/unicable-ii-power-inserter-5-2400mhz
Or a homemade one which lacks all electronic wizardry that stops the 22kHz signals, and so it works!!
A right minefield!!
Sounds very likely to me, though I admit I hadn't really thought about it before you mentioned it.
There will be a capacitor between the in and out ports on the power inserter to pass the RF through while blocking power.
If the value isn't chosen with passing 22kHz in mind it is likely that it won't pass 22kHz very well.
Also there will be an inductor between the power in port and the RF port that's supposed to be receiving the power. It's supposed to stop any RF being wasted by going up the power in port rather than passing though as intended.
Again if it's value isn't chosen with blocking 22kHz in mind it's likely that it won't block 22kHz much at all.
Now I know that the home made power inserter didn't have an inductor and it worked but the ready made unit may also have a capacitor on the power in port to short any remaining RF to ground making the inductor essential.
What puzzles me somewhat is that the sticky tape and copper foil capacitor in the home made power inserter was able to pass enough 22kHz.
Maybe the fact that it was in the shield rather than the centre wire somehow meant that a good circuit at 22kHz wasn't so important.
After some digging around, and as I understand it, it is not clear if the Sky 161 is to EN50494/EN50607 standards which passes 22kHz signals from the receiver to the LNB, including Unicable II LNB to set the bands. The power inserter I bought, which doesn't work, doesn't mention EN50494/EN50607 in it specifications. Neither does the GT-Sat GTPI1 Unicable / Universal LNB Power Inserter with 15V DC PSU as sold by World of Satellite.
These units have a typical frequency range of 5 - 2200 mHz.
Perhaps a real techie can comment??
The only power inserter that I have found and which mentions EN50494/EN50607 is the Inverto unit - https://www.inverto.tv/accessories/326/unicable-ii-power-inserter-5-2400mhz
Or a homemade one which lacks all electronic wizardry that stops the 22kHz signals, and so it works!!
A right minefield!!
All 3 inserters you mention specify 5 to 2000+ MHz irrespective of them being specified for unicable or not.
The Vision inserter you have purchased does not specify any use for unicable and the data shows it powering
i) A Quattro LNB (and not the associated switch)
ii) A switch connected to a Quattro LNB
iii) or both the above.
In all cases it's the LNB to switch side of the system where the power inserter is placed and not the box to switch side of the system
A Quattro LNB doesn't require (22kHz) control signals because the LNB outputs Vlow V, Vlow H, Vhigh V, Vhigh H in parallel.
My guess is that you have purchased a Vision power inserter for a different application, and for a system that has been around long before the unicable became available.
https://catalogue.solutionsgroup-plc.com/media/vision/intergrated-reception-systems/ev5-ev9-accessories/switchable-direction-dc-inserter-line-power-tap/V5-033.pdf
These units have a typical frequency range of 5 - 2200 mHz.
The one you bought has a spec of 5 – 2150MHz, the one from WoS 5 ~ 2350 MHz
Np idea if that makes any difference.
Don't think it makes any difference. On the GigaBlue SCR LNB the 24 User bands range from 1005 mHz to 2130 mHZ and I'm using Bands 1 - 8 - 1005, 1050, 1095, 1140, 1210, 1420, 1680 and 2040. Might move some of the bands to the centre anyway as there must be some roll off at the lower and upper ends of a band. Bit like a spring - using the centre part of its range.
But I've got a couple of supplementaries:
1. On the FBC tuners C-H, should the external power be set to Yes or No?? Or doesn't it make a difference. Physical tuners A and B are both set to Yes.
2. For the SCR LNB Unicable II power, the GT Sat DC injector is 15v and the Inverto DC injector is 17v. The Inverto SCR LNBs specs indicate a voltage of 13.5v and 300ma??
The GT Sat LNB I guess it is 15v as their DC injector is 15v.
Haven't found a specified voltage for the Gigablue SCR LNB. Only 300ma current.
I'm using 15v DC at the moment which seems to be OK and hopefully isn't cooking the LNB.
Emailed GigaBlue but no reply, wondered if anyone knew??
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