This is divided into two seperate bodges, bodge (a), and bobdge (b), as you will be aware a true bodger moves swiftly from one c*ck-up to another, unphased by his complete lack of competence :O)
Bodge (a).
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With the aid of a signal booster (4 way as it happens), I had been enjoying watching TV (on my Television) via my Freeview box and also on my PC via a Freecom (DVB) USB stick. Not satisfied with this happy state of affairs I thought why not move the signal booster out of the living room up into the loft, where it would be 'out of the way' and also able to power the aerial socket in the kitchen (unconnected at the time). I figured that I could use a passive splitter in the living room once the signal was being boosted from the loft.
I just ran an extennsion cable to the loft for power to make things 'easy'. Anyway I put the booster in the loft so it was powing the two down leads. When I tried to use the passive splitter I had in the living room I found that only one of the 'ports' was working, as I had no other splitter I decided to 'make one myself' by combining some cables (none of the impedance matching bull for me!!) anyway as I was trying to connect this up I (at come point) felt a 'tingling' feeling in my fingers. That doesn't feel right I though, so I went and got the booster from the loft and tried it in its previous configutation in the living room and as I suspected it was no longer working (although its blue light was on and the fuse was not blown).
Actually I am not 100% sure it is buggered, cos some of the cables I made up can be a bit dodgy. However I just tested it again it is buggered, it will let a signal through albeit a bad one, worse than unboosted. Interestingly the gain controls still works, it varies from a crap picture to an abysmal on (testing on analogue). (I might have a go at fixing that later).
So I am now wondering what caused it to blow? I rechecked my cable, especially looking for 'earth to signal' 'shorts but the cable seemed fine, the main problem with these cables is asembling the connectors on them and not getting an open circuit on the signal. Anyway down to just an unboosted signal I tired to see if my signal splitter cable would work anyway, it turns out it did at least on the strongest muxes but no chance on the weaker ones as I expected. Dunnno if a propper spliitter would have faired any better. Anyway I also got the 'tingling' sensation when fiddling with the splitter cable soI am wondering what is going on? There is no booster so the energy is not coming from there so that leaves just the USB stick or the Freeview box. I am not 100% sure exactly when I got the tingling but I think it was when touching the earths shields of two different cables. Lets face it you can only really tough the earths, not the signal because it is inside. So I am figuring there is a difference between the two earths or something? Actually it would have to be quite a big difference wouldn't it? I mean You don't get a tingling from say, a 9 volt battery do you, rather worrying!! Actually I am going get my voltmeter out right now and test the two earths potential differences!! I might be in for a shock! Quite literally!!
Hmmmm..interesting I am recording a 4-5 volt difference between the two earths!! Perhaps more to the point, I noticed that 'at first contact' on one of the tests it appeared to register 18 volts!!! (and then drop back to 4-5 volts) is this normal? Incidently the tingle I experienced in my fingers gave me the impression it was high voltage, similar to something I experience from a faulty light switch (nothinig to do with me I might add!!), seems like there maybe some capacitive effect here? I should add that the TV and PC are on different power sockets, but the sockets are probably on the same 'spur' or 'ring' they are in the same room anyway!! I will try and connect them to the same socket to see if this that is any better.
This leads me to another thought, the signal booster 'blew' when it was in the loft, powered from an upstairs socket, it never blew when it was down stairs, even though that 4-5 volt earth difference was present. Maybe the situation is even worse with three different sockets interacting? Also I wonder if I can take it back to the shop (Maplins) as faulty, I don't have the receipt though. As far as I can see it 'blew' whilst in 'normal usage'? I don't think my 'homemade' signal splitter can be blamed. Another though is why my 'propper' signal splitter failed? Did it burn out due to some earth level problem? Or was it just because it was dirt cheap (a few quid) and shoddily made (very tight connector fittings requiring some force?).
Bodge (b).
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Moving on somewhat, undeterred by my recent failures I decided to try and boost the signal in the loft by adding another identical aerial, side by side with the original areial in the loft. I tried as well as I could (well I made an effort) to keep the aerials parallel and have the same length of cable to each aerial (about two nine inch lengths twisted on to the original length. This however I had no success the resulting signal was worse, much worse!! I could only get a very block picture on the best mux and nowt on the others!! I tried to adjust the aerials alignment a little but it made no difference. Then I wondered if it mattered which way around the earth and signal were connected to the aerials. The aerials recieve a vertical signal, I noticed that one had the earth connected to the top 'connector' and the other had the earth connected to the bottom connector, however I also noticed that one of the aerials was upside down so to speak, in respect to the other, such that it needed to be turned 180 degrees on its long axis to be oriented the same way. I though that these two 'errors' might cancel each other out (if indeed it mattered at all) and that the resulting two signals would be back 'in phase', however I am not too sure. Anyway I gave up at this point and went back to a single aerial as it was getting late. Any comments regarding me combining the two areials like this? OK maybe I should have used a propper 'combiner' to match impedances or whatever, but the one I have doesn't work so I couldn't use that. I was pretty disapointed with the results I got, the first thing I thought is that the signals are close to completely out of phase, almost cancelling each other out, just how accurate do you have to be? What is the margin of error? My guess is the maximum difference the alignment, mounting and cabling could have ammounted to would be about 2 iinchs, but probably a lot less.
Anyway I will have another 'bash' at it tomorrow, this time I will measure the cable lengths accurately and make sure the aerials are orientated the same way with the earths and signals connected to the appropiate 'studs', incidently uk TV wavelengths are 40-80 cm (approx). I am hoping I got my signals 180 degress out for phase with my first 'bash' hoping for better luck tomorrow. I am going to carry my portable TV in the loft as a 'signal tester', hopefully without breaking my neck.
Future plans
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I have put off adding a 'proper' powerpoint to the loft for the time being for obvious reasons :O)
I might have a go at fixing my signal booster some time, probably be cheaper to buy a new one though.
Maybe the diagram is simiilar to this? Probably the transistor thingy is blown? Fook knows.