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Hi Len,
5MHz is half-way between America's 4.5MHz and Europe's 5.5MHz TV audio IF transformers' frequencies. They use powdered iron cores that are adjustable.
Thanks Audio,
I did think of using radio IF transformers. I know they are tuned to 455 kHz, but I'll measure the inductance of the ones I have and see if they are near the 2 uH. I don't think I have any IFs from a TV.
For an air core coil of 2 uH, wind 21 turns #30 wire on a 1/4" form, close spaced. For other values use this formula: L = N^2*(R^2/(9*R + 10*Le))
where
L = inductance in microhenries
N = number of turns
R = radius of coil
Le = length in same units as radius
Your inductance won't need to be very accurate unless there are many sections in the filter. I have had good results using this equation and tweaking the length in multi section filters.
Are you sure that the R & Le can be in either imperial or metric?
The dimensions are length squared divided by length which has the dimensions of length (N is dimensionless of course). So I would have thought that there would have to be a constant for either imperial or metric (or both).
Hi Len,
5MHz is half-way between America's 4.5MHz and Europe's 5.5MHz TV audio IF transformers' frequencies. They use powdered iron cores that are adjustable.
As Styx says, NOT Europe, just the UK - the UK has only ever used 625 line TV on UHF (out old 405 line system was still on VHF), so we were able to adopt a slightly higher quality system using a 6MHz inter-carrier frequency, continental Europe used VHF 625 as well as UHF, so used 5.5MHz inter-carrier to suit the narrower bandwidth. (Known as PAL-I and PAL-B/G).
So, just for a change, being the first broadcasters of TV worked out well for the UK (eventually!) - unfortunately, being the first broadcasters of colour TV didn't work out so well for the USA :cry: who still have the inferior NTSC system. Still, digital TV is curing all that :lol:
I thought that The Tunnel joined the UK to Europe!
NTSC (never the same colours) has been fixed for a while on all but the oldest stations. They blame the problem on phase-shift in old video recorders. Actually, they had phase-shifts all over the place which they corrected when the new video recorders didn't solve the problem.
They also use better make-up now. :lol:
NTSC (never the same colours) has been fixed for a while on all but the oldest stations. They blame the problem on phase-shift in old video recorders. Actually, they had phase-shifts all over the place which they corrected when the new video recorders didn't solve the problem.
They also use better make-up now. :lol:
It's basically an inherent defect of NTSC, it can perhaps be 'papered over' a little, but to cure it requires a new system - however, it would be pointless as digital TV is replacing it.
NTSC (never the same colours) has been fixed for a while on all but the oldest stations. They blame the problem on phase-shift in old video recorders. Actually, they had phase-shifts all over the place which they corrected when the new video recorders didn't solve the problem.
They also use better make-up now. :lol:
It's basically an inherent defect of NTSC, it can perhaps be 'papered over' a little, but to cure it requires a new system - however, it would be pointless as digital TV is replacing it.
Except its not. Everyone in the world expected the UK to suffer the biggest switch-over problem (being the pioneers and the first to roll it out and all). BUT it seems the US are having the biggest problem.
Why? because of the Media companies unwillingness to change over.
Lobbying in the US pretty much runs the country and the media companies are lobbying extreamly hard for no timescale to switchover.
Why? becuase of revenue from customers, IF they are forced into a changeover they cannot force consumers to change over and thus they fear they will lose watchers and thus advertisment funding.
Equally they dont want to give out their freq ranges
They are really hampering the changeover.
As opose to the UK which pioneering digital TV, more importantly BBC was pioneering it, thus since a non-advertiment entity was providing it (and with less channels on the whole) 2 out of 5 is a large proportion so it was easier for the other 3 (ITV,Ch4,FIVE) to take the leap.
The US are extreamly far behind of mobile phone tech. my mate has just come back after 4years and for those 4years he has been constantly bitchen about the "bricks" they have and the lack of features. 6months before he left he actually bought a nk6680 cause he was getting hacked off, the general populous had no idea there were phones like it (and he worked in a hi-tech software house). He is back now and is loving the 3G access
So it seems the US will be falling behind of infomation to the general populous again (but ignorance is the best way to control people)
I thought that The Tunnel joined the UK to Europe!
NTSC (never the same colours) has been fixed for a while on all but the oldest stations. They blame the problem on phase-shift in old video recorders. Actually, they had phase-shifts all over the place which they corrected when the new video recorders didn't solve the problem.
They also use better make-up now. :lol:
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