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I have a small collection of old TVs and most have no input besides over-the-air VHF. I have an old Ramsey TVC6 kit (three, actually) that's swamped out by WiFi when the transmission antenna is more than a couple feet from the receiving antenna. How can I magnify its signal the circuit (shown here: http://www.allspectrum.com/ramsey/TV6C/TV6.pdf ) to be stronger than the local WiFi? I've already been told to remove resistor r12 and replace it with nothing but a straight wire and replace the caps with NPO caps. What else? How can I change this circuit to broadcast over the Band III VHF channels, 7-13? It currently only does Band I, channels 2-6. There's no risk of interfering with anyone else's WiFi -- I can't pick up any at even a weak signal here besides my own.
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Feb 10, 2021 04:42
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| # ? May 5, 2024 22:39 |
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Might want to post your question in the electronics thread because there are people who know way more about this than I do but you really shouldn't get swamped by WiFi on a TV I don't think. WiFi is either 2.4GHz or 5GHz and both are way above VHF; Channel 13 has an upper edge of 216MHz. Does it happen to every single TV set or just some of them? Kind of sounds like all of them so my suspicion is that the WiFi noise is getting picked up by the Ramsey TVC6 circuitry and ending up in its output. I would try to shield that first if it's not, I can't find a picture of one to check. The manual you linked makes me think it's just a bare circuit board. Can you clear it up with a little tinfoil tent over the board maybe (careful not to short anything)? If you have an alligator clip lead, clip the foil to ground as close to the power input as possible, but it probably would help a little bit even without being grounded. If that does make it better, maybe look into a metal case to hold the transmitter. Be sure to ground the case.
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Feb 10, 2021 15:42
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Can you point out the electronics thread? Sorry, I've never been to this forum -- I was pointed here by Ask/Tell. Color TVs, especially. B&W seem more resilient. It's definitely WiFi, as the nearer I get to it, the more swamped out the picture becomes.
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Feb 10, 2021 22:32
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No worries, just pointing out the electronics thread because I think more of the relevant eyes are likely to notice it there is all: https://forums.somethingawful.com/showthread.php?threadid=2734977 B&W TV is probably a lot more likely to tolerate the noise because the B&W information isn't using nearly as much of the channel bandwidth generally. They're probably also generally older sets or simpler designs and just naturally filter out the higher frequency noise simply because they aren't fast enough to respond to it (because they don't need to). But anyway, I don't doubt the WiFi is affecting you I just think it's affecting the transmitter rather than the TVs. The TV antenna is unlikely to have a good response at 2.4GHz, the whole point of the antenna and tuner is to selectively pick out a narrowish band of frequencies. The antenna and tuner should be greatly reducing (attenuating is the fancy official word) the signal for all other parts of the spectrum than the part you care about, which is the channel you have selected. Likewise for the sending antenna on the unit. So my suspicion is the the WiFi is being picked up further up the chain in the the circuitry of the Ramsey unit and ending up as noise in its output e.g. it could be adding noise to your power lines. I did eventually find some pictures of it and it does look like it's in a box, but I couldn't tell if it's a shielded box (metal) or not. If it's not already metal you could try wrapping the box in foil as a crude test shield. It'll work best if the foil also is grounded which could be done by simply making sure it touches the threads on the output coax or whatever.
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Feb 10, 2021 23:50
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Posted in the Learning electronics thread. Closing this one.
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Feb 11, 2021 01:32
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