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Indoor FM boost with no cables?
Hello. I've seen many 'boosters' for radio reception, none of which do what
I'm hoping for, so either my aim is foolish beyond imagining, or really interesting. Please tell me which. :) I hope to boost the incoming signal to override the ocal RF mush from nearby flats, and to do this for a portable receiver so I want no cables attached to it at all. I have considered two possible ideas: 1. Take a feed from my existing outdoor antenna and make a dipole indoors, for passive re-radiation of whatever the outdoor one picks up. 2. Same thing, but using a small preamp I built once (uses a MAR6 I think, about 22dB gain), but instead of feeding the RF input on a tuner as usual, drive a small dipole to allow any small receiver with a whip or a wire to get enough of the externally derived signal to beat the indoor mush. (I think that feedback would be a problem, with any serious power, but perhaps something as small as the MAR6-based booster I mentioned might work ok, given that the outdoor antenna is several tens of feet distant. Anyway, that's the idea, and if it, or something I haven't thought of or mentioned at all will solve this for me, please tell me. Alternatively, please tell me what is the impossible obstacle to this notion...) Crow. |
Indoor FM boost with no cables?
In article ,
Lostgallifreyan wrote: Hello. I've seen many 'boosters' for radio reception, none of which do what I'm hoping for, so either my aim is foolish beyond imagining, or really interesting. Please tell me which. :) I hope to boost the incoming signal to override the ocal RF mush from nearby flats, and to do this for a portable receiver so I want no cables attached to it at all. I have considered two possible ideas: 1. Take a feed from my existing outdoor antenna and make a dipole indoors, for passive re-radiation of whatever the outdoor one picks up. This might help a bit, depending on how good a signal your outdoor antenna gets, and on proximity between your indoor antenna and the portable receiver. 2. Same thing, but using a small preamp I built once (uses a MAR6 I think, about 22dB gain), but instead of feeding the RF input on a tuner as usual, drive a small dipole to allow any small receiver with a whip or a wire to get enough of the externally derived signal to beat the indoor mush. (I think that feedback would be a problem, with any serious power, but perhaps something as small as the MAR6-based booster I mentioned might work ok, given that the outdoor antenna is several tens of feet distant. This *might* work, but as you note it has some problems. Feedback could very well be an issue (and could be quite unpredictable as it could change from day to day or minute to minute depending on the presence or absence of signal-reflecting objects near the retransmit antenna). Also, it may not be strictly legal. Your "booster" would be, in effect, a miniature broadcast station, (re)transmitting the whole spectrum (not necessarily just the radio stations that you care about). A single-channel (re)transmitter might be legal here in the U.S. under Part 15 regulations... but boosting and transmitting everything that got into the outdoor antenna could really be problematic. You could end up making reception worse for your flat-neighbors, if the system you were boosting/repeating interfered with direct reception of the same signal. |
Indoor FM boost with no cables?
On Fri, 25 Jul 2014, Lostgallifreyan wrote:
Hello. I've seen many 'boosters' for radio reception, none of which do what I'm hoping for, so either my aim is foolish beyond imagining, or really interesting. Please tell me which. :) I hope to boost the incoming signal to override the ocal RF mush from nearby flats, and to do this for a portable receiver so I want no cables attached to it at all. I have considered two possible ideas: Modify the radio so coax can be attached, and feed it from the good antenna outside (or even just positioned well inside). Or, buy a radio that already has an external antenna jack. For FM, local interference should be less of a problem, since most of it is AM. It would have to be quite strong to wipe out decent strength FM signals. That said, what you need is to get stronger signals, so they capture the limiters in the receiver. Coincidentally, this week I came across a reprint of a great article from Audio Magazine back in January 1991, where the author talks about getting the dipole further up, and oriented properly, and then goes on to show a collinear antenna made from 300ohm twinlead and some wire. A better antenna is probably a good thing, and if it can be oriented to improve wanted signals but not be so good for interfering signals, that's a good thing. The article is he http://home.earthlink.net/~schultdw/...Reception.html But connecting directly to the radio is going to make the best improvement. If you need the signal stronger than the local noise, any amplification or remodulating transmitter will have to be stronger than the local noise, and since radio signals drop off rapidly with distance, a too strong for legal signals is likely to be needed. Michael |
Indoor FM boost with no cables?
On Fri, 25 Jul 2014 14:21:07 -0500, Lostgallifreyan
wrote: I hope to boost the incoming signal to override the ocal RF mush from nearby flats, and to do this for a portable receiver so I want no cables attached to it at all. I have considered two possible ideas: I've actually done something like that for a customer, but first, I'll take apart you two possible ideas; 1. Take a feed from my existing outdoor antenna and make a dipole indoors, for passive re-radiation of whatever the outdoor one picks up. Passive repeaters do not work well. I can go through the calculations for you but basically, you get approximately twice the path loss with a passive repeater, as you would with a direct path. I can grind the numbers for you if you want later (I'm giving a talk tomorrow and need to get some sleep). 2. Same thing, but using a small preamp I built once (uses a MAR6 I think, about 22dB gain), but instead of feeding the RF input on a tuner as usual, drive a small dipole to allow any small receiver with a whip or a wire to get enough of the externally derived signal to beat the indoor mush. What is there to keep the amplifier from amplifying the "mush"? If you point your directional antenna in the wrong direction, you just as easily be pointing it at the source of the noise. However, that's a minor problem compared to multipath. You will still have some signal arriving directly from the FM station, which will combine in some random fashion with the amplified signal. If the phase difference between the incident and amplified paths is 180 degrees, you'll have a null and no signal. At 100 Mhz, 1/2 wave is about 1.5 meters, so you'll have nulls every 1.5 meters inside your house. (I think that feedback would be a problem, with any serious power, but perhaps something as small as the MAR6-based booster I mentioned might work ok, given that the outdoor antenna is several tens of feet distant. Yes, it will be a problem. If you want to do that, read about how the various cell phone bi-directional amplifiers prevent feedback. (warning: It's messy). Anyway, that's the idea, and if it, or something I haven't thought of or mentioned at all will solve this for me, please tell me. Alternatively, please tell me what is the impossible obstacle to this notion...) David Platt had the right idea. Build a repeater. You start with a quality FM receiver that has a coax connector for the antenna. Hopefully, it would get good reception and not pickup as much noise. The audio output of the FM receiver would drive a Bluetooth wireless speaker arrangement. Trade your portable receiver for a pair of BT earphones or maybe a smartphone with BT. I suggest you go with the newer BT 4.0 (BT Low Energy) instead of the older BT 3.0 (BT standard). Range is about 10-30 meters, which should be adequate. Something like this: http://www.ebay.com/itm/311024899511 Search for: Bluetooth audio transmitter. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Indoor FM boost with no cables?
Michael Black wrote in
news:alpine.LNX.2.02.1407260017460.20123@darkstar. example.org: Modify the radio so coax can be attached, and feed it from the good antenna outside (or even just positioned well inside). Or, buy a radio that already has an external antenna jack. Now that would be cheating. :) Actually the one I bought does have one, but the point was convenience, allowing local tuning as usual but with no unwanted wires trailing around as I carry a radio between rooms while working. If it were practical I imagine we'd all be doing it, I just wondered if there might be soem compromise I can use, but likely not one that isn't already standard practise. |
Indoor FM boost with no cables?
Jeff Liebermann wrote in
: Passive repeaters do not work well. I can go through the calculations for you but basically, you get approximately twice the path loss with a passive repeater, as you would with a direct path. I can grind the numbers for you if you want later (I'm giving a talk tomorrow and need to get some sleep). No need, but thankyou. I read about them a bit. I get the idea that they're huge, totally impractical as a spot fix for a few rooms in a basement flat. What is there to keep the amplifier from amplifying the "mush"? Plenty. :) The mush is very localised, some widget (likely a wireless net box or router) in the upstairs flat, it is not detectable beyond a quarter of the distance to my outside antenna. Hence, wondering if a tiny boost and an indoor dipole might be enough to overcome the immediate locality without annoying the neighbours. See, if that mush does not reach the outdoor antenna in any measurable degree, it seemed to follow that a tiny boost to adequate levels might also fail to reach that outdoor antenna, and thus feedback might be avoided, as well as unwanted transmission strength beyond my boundaries. Purely speculative, but it seems logical enough to me... |
Indoor FM boost with no cables?
On 7/26/2014 6:15 AM, Lostgallifreyan wrote:
Jeff Liebermann wrote in : Passive repeaters do not work well. I can go through the calculations for you but basically, you get approximately twice the path loss with a passive repeater, as you would with a direct path. I can grind the numbers for you if you want later (I'm giving a talk tomorrow and need to get some sleep). No need, but thankyou. I read about them a bit. I get the idea that they're huge, totally impractical as a spot fix for a few rooms in a basement flat. What is there to keep the amplifier from amplifying the "mush"? Plenty. :) The mush is very localised, some widget (likely a wireless net box or router) in the upstairs flat, it is not detectable beyond a quarter of the distance to my outside antenna. Hence, wondering if a tiny boost and an indoor dipole might be enough to overcome the immediate locality without annoying the neighbours. See, if that mush does not reach the outdoor antenna in any measurable degree, it seemed to follow that a tiny boost to adequate levels might also fail to reach that outdoor antenna, and thus feedback might be avoided, as well as unwanted transmission strength beyond my boundaries. Purely speculative, but it seems logical enough to me... If the box is putting out that much interference, there's a good chance it has a problem (and may be operating illegally). I would think correcting the problem at the source would be the better option. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
Indoor FM boost with no cables?
Jerry Stuckle wrote in news:lr0908$usv$1@dont-
email.me: If the box is putting out that much interference, there's a good chance it has a problem (and may be operating illegally). I would think correcting the problem at the source would be the better option. Nope. It's one of those consumer widgets, one o millions, that have a disclaimer saying that some limited interference must be accepted. Knowing this, it isn't even worth trying to police the issue, and probably impossible anyway. Computer based stuff just does this to us, there's no stuffing THAT genie back in the bottle now. |
Indoor FM boost with no cables?
On 7/26/2014 10:02 AM, Lostgallifreyan wrote:
Jerry Stuckle wrote in news:lr0908$usv$1@dont- email.me: If the box is putting out that much interference, there's a good chance it has a problem (and may be operating illegally). I would think correcting the problem at the source would be the better option. Nope. It's one of those consumer widgets, one o millions, that have a disclaimer saying that some limited interference must be accepted. Knowing this, it isn't even worth trying to police the issue, and probably impossible anyway. Computer based stuff just does this to us, there's no stuffing THAT genie back in the bottle now. That does not mean it's not operating illegally. Even with such a tag, it can be emitting a signal illegally. ALL potential sources of RF have limits on their emissions. Exceed those limits and they are not operating legally. It may be due to shoddy workmanship or a problem with the device itself. -- ================== Remove the "x" from my email address Jerry Stuckle ================== |
Indoor FM boost with no cables?
On 7/26/2014 12:32 AM, Jeff Liebermann wrote:
On Fri, 25 Jul 2014 14:21:07 -0500, Lostgallifreyan wrote: I hope to boost the incoming signal to override the ocal RF mush from nearby flats, and to do this for a portable receiver so I want no cables attached to it at all. I have considered two possible ideas: Hey Jeff, Is it possible to build a tuned loop connected to the backside of the radio, to cover the FM band. I never tried a loop at 100Mhz. Mikek --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com |
Indoor FM boost with no cables?
On Sat, 26 Jul 2014 09:22:08 -0500, amdx wrote:
Hey Jeff, Is it possible to build a tuned loop connected to the backside of the radio, to cover the FM band. I never tried a loop at 100Mhz. Mikek Sure. Google for VHF magnetic loop antenna. https://www.google.com/search?q=vhf+magnetic+loop+antenna&tbm=isch They work so-so, but have the same problem as the HF version. The Q is very high resulting in extremely narrow usable bandwidth. In order to make it work, there would need to be some way of tuning the loop to frequency. Making it track the receiver frequency would be a big plus. http://www.m0ukd.com/wordpress/homebrew/magnetic-loop-antennas/ He forgot to insert a series tuning cap in the gamma match, but otherwise, it should give you an idea of what's involved. http://www.iw5edi.com/technical-articles/144-mhz-magnetic-loop-antenna Much better. Anyway, recalculate for 100 MHz and it should work. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Indoor FM boost with no cables?
On 7/26/2014 10:15 AM, Jeff Liebermann wrote:
On Sat, 26 Jul 2014 09:22:08 -0500, amdx wrote: Hey Jeff, Is it possible to build a tuned loop connected to the backside of the radio, to cover the FM band. I never tried a loop at 100Mhz. Mikek Sure. Google for VHF magnetic loop antenna. https://www.google.com/search?q=vhf+magnetic+loop+antenna&tbm=isch They work so-so, but have the same problem as the HF version. The Q is very high resulting in extremely narrow usable bandwidth. In order to make it work, there would need to be some way of tuning the loop to frequency. Making it track the receiver frequency would be a big plus. I expected to have a tuning cap on the loop to tune to his frequency of interest. I don't know about polarization, but he may be able to rotate out some interference with a loop. Mikek --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com |
Indoor FM boost with no cables?
Jerry Stuckle wrote in news:lr0d4e$spo$1@dont-
email.me: That does not mean it's not operating illegally. Even with such a tag, it can be emitting a signal illegally. ALL potential sources of RF have limits on their emissions. Exceed those limits and they are not operating legally. It may be due to shoddy workmanship or a problem with the device itself. Could be so, but like weed-smoking, popular round here, though I haven't done it myself for at least twenty years and do not like it, is a live-and-let- live thing, not a call-the-police thing. Also, if I start shouting about a small bit of interference, people might start shouting about not liking my solar panels outside the house looking (to their eyes) unacceptably ugly, etc... Also, the cost of the expert witness to prove it in court is a cost so extreme in proportion to the problem that I won't consider it viable. I suspect it's well within limits actually, no worse than half the small collection of stuff I have like mice and keyboards emit. It's just what was left after I'd turned off all I could control, in a basement that very little external RF penetrates into anyway. Hence me steering the discussion back to the notion of a gentle boost for the immediate locality. :) |
Indoor FM boost with no cables?
amdx wrote in :
I expected to have a tuning cap on the loop to tune to his frequency of interest. I don't know about polarization, but he may be able to rotate out some interference with a loop. Slightly cubersome for my situaion but technically true, so a nice idea. Thanks. |
Indoor FM boost with no cables?
On 7/26/2014 1:19 PM, Lostgallifreyan wrote:
amdx wrote in : I expected to have a tuning cap on the loop to tune to his frequency of interest. I don't know about polarization, but he may be able to rotate out some interference with a loop. Slightly cumbersome for my situation but technically true, so a nice idea. Thanks. Ya, I'm thinking a 3 or 4 turn loop to fit the back of the radio. I had to work all day, earlier I had thoughts about putting one my GE Suoerradio III just to see if it works. A spiral form may be less cumbersome. I have a bunch of ten pf caps, but I haven't calculated anything yet so don't know if 2pf to 10pf would resonate with a reasonable size coil. Mikek --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com |
Indoor FM boost with no cables?
On 7/26/2014 10:57 AM, amdx wrote:
On 7/26/2014 10:15 AM, Jeff Liebermann wrote: On Sat, 26 Jul 2014 09:22:08 -0500, amdx wrote: Hey Jeff, Is it possible to build a tuned loop connected to the backside of the radio, to cover the FM band. I never tried a loop at 100Mhz. Mikek Sure. Google for VHF magnetic loop antenna. https://www.google.com/search?q=vhf+magnetic+loop+antenna&tbm=isch They work so-so, but have the same problem as the HF version. The Q is very high resulting in extremely narrow usable bandwidth. In order to make it work, there would need to be some way of tuning the loop to frequency. Making it track the receiver frequency would be a big plus. I expected to have a tuning cap on the loop to tune to his frequency of interest. I don't know about polarization, but he may be able to rotate out some interference with a loop. Mikek I've* calculated a 6 inch loop made with a #12 or #14 wire will resonate the FM band with a cap between 6.5pf and 10pf. Roughly! Now, I'll see if I can generate the gumption in the next couple of days to build it to see if it has any positive effect. I hope someone beats me to it. With an AM loop and radio the signal couples to the internal loop very well, I don't know how well you can couple a signal into an FM radio. Mikek * actually I used a couple of online calculators. http://www.deephaven.co.uk/lc.html http://www.daycounter.com/Calculator...lculator.phtml |
Indoor FM boost with no cables?
On Sat, 26 Jul 2014 09:02:44 -0500, Lostgallifreyan
wrote: Nope. It's one of those consumer widgets, one o millions, that have a disclaimer saying that some limited interference must be accepted. Knowing this, it isn't even worth trying to police the issue, and probably impossible anyway. Computer based stuff just does this to us, there's no stuffing THAT genie back in the bottle now. Much depends on the device causing the problem. It's often cheaper and easier to just buy the owner a new device instead of trying to fix it. I've done that a few times with Chinese junk that never had a prayer of meeting FCC Part 15 incidental radiation limits. So far, I've replaced one ethernet switch, one 4 line phone, and 2 security cameras in the neighborhood. Also, a mess of junk switcher type cell phone chargers. However, you can't do that if you don't know what's causing the noise. So, take your portable radio, wrap it in aluminum foil to REDUCE the sensitivity, and snoop around the building until you find the culprit. The rest you can figure out yourself. Hint: Diplomacy works. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Indoor FM boost with no cables?
Jeff Liebermann wrote in
: Much depends on the device causing the problem. It's often cheaper and easier to just buy the owner a new device instead of trying to fix it. I've done that a few times with Chinese junk that never had a prayer of meeting FCC Part 15 incidental radiation limits. That could work. :) I agree, the price of the widget and a bit of diplomacy might go further than any other effort. If it becomes a problem I'll try that. |
Indoor FM boost with no cables?
amdx wrote in :
I've* calculated a 6 inch loop made with a #12 or #14 wire will resonate the FM band with a cap between 6.5pf and 10pf. Roughly! Now, I'll see if I can generate the gumption in the next couple of days to build it to see if it has any positive effect. I hope someone beats me to it. With an AM loop and radio the signal couples to the internal loop very well, I don't know how well you can couple a signal into an FM radio. Mikek * actually I used a couple of online calculators. http://www.deephaven.co.uk/lc.html http://www.daycounter.com/Calculator...lculator.phtml This is nice because it beats the issue with two ways to be selective. Even so, I have to have one last shot at the broadband notion: could a 6dB boost with one of those MAR6-based antenna amps be worth a shot? Driving a local diple, taped to a doorframe perhaps, in the centre of the flat? Given the tiny size of those IC's I doubt the amount of power getting out of the flat will be a nuisance, especially given its reluctance to allow RF in (except through the celing, and a dipole taped vertically to a doorframe isn't going to send a lot upwards either.. To some extent the business may be eased by the fact that the two frequencies I'm most keen to get, 91.5MHz and 93.7MHz, aren't far apart. If there is ANY chance this can be solved with no modification or encumbrance to the tiny radio I intend to carry from room to room, that's the way I want to do it. |
Indoor FM boost with no cables?
Jeff Liebermann wrote in
: Also, a mess of junk switcher type cell phone chargers. Nice catch. The noise has a pulsed interval very similar to the type of Li- ion charger that pauses to measure voltage every second or so. It might be one. Thing is, it is the interval that noises, not the main duration, so I think it might be a net boz sending regular packets when idle. |
Indoor FM boost with no cables?
In article ,
Jeff Liebermann wrote: Much depends on the device causing the problem. It's often cheaper and easier to just buy the owner a new device instead of trying to fix it. I've done that a few times with Chinese junk that never had a prayer of meeting FCC Part 15 incidental radiation limits. So far, I've replaced one ethernet switch, one 4 line phone, and 2 security cameras in the neighborhood. Also, a mess of junk switcher type cell phone chargers. *rolls eyes* A few years ago I helped chase down a noise source which was wandering randomly through the 2-meter repeater input sub-band, and causing prolonged noisy squelch tails on the ends of transmissions on several different repeaters in the Silicon Valley area. It turned out to be a (famous name) 5-port Ethernet hub, which was leaking its internal clock-oscillator signal into all ports and back into its power supply and was "turning the entire home wiring into a giant antenna" (as the house-wiring-TV-antenna gimmicks used to say, decades ago). Horrid... I could practically hear my spectrum analyzer cringe. The owner was extremely cooperative, immediately agreed when I offered to replace the hub with one from my own collection of spares, and the problem went away and hasn't recurred in the years since. An unusual failure mode, I guess (fortunately!) |
Indoor FM boost with no cables?
On Fri, 25 Jul 2014 14:21:07 -0500, Lostgallifreyan wrote:
I hope to boost the incoming signal to override the ocal RF mush from nearby flats ... It might be wiser to see if you can identify the source(s) of the offending "mush" instead. You would be doing yourself and others a service by doing so. Contact your local authority and see if they will look into it. Can't hurt to try, and the rewards may be worth it. |
Indoor FM boost with no cables?
On Sat, 26 Jul 2014 21:24:11 -0700, (David
Platt) wrote: It turned out to be a (famous name) 5-port Ethernet hub, which was leaking its internal clock-oscillator signal into all ports and back into its power supply and was "turning the entire home wiring into a giant antenna" (as the house-wiring-TV-antenna gimmicks used to say, decades ago). Horrid... I could practically hear my spectrum analyzer cringe. Yep. I also know how to shoot myself in the foot. When I replaced the neighbors noisy ethernet switch, he gave me the old switch for recycling. Instead, I threw it into my pile of network boxes for a later autopsy. After about a year, the post-it note marking it as defective was lost. I needed a switch for the local club station, so I grabbed the noisy switch and left. The complaints started about a week later. Oddly, the 2.4GHz link between the repeater building and the club station was the first to suffer interference problems. I think just about every radio on the hill had problems, including the county radios. On the principle of "whatever I did last was probably wrong", I retraced my steps and eventually found the noisy switch. I recall that it was made by Edimax, but don't recall the exact model number. As for "turn your house wiring into a giant TV antenna", that was my start in electronics. I recall the ads in the back of Popular Electronics and was intrigued by the principle. I learned that inside the magic coupling box was a "capacitator" and that if one had an AC-DC powered TV, it could be rather dangerous if connected improperly. What got my attention was that it was an obvious fraud, yet also quite successful considering that the ads were everywhere and appeared in every electronics magazine. Instead of the traditional policeman or fireman, I decided to become an electronics crook when I grew up. That was heady stuff for a 9 or 10 year old. My parents grudgingly approved if I agreed to become and engineer first, and later a crook. That seemed reasonable and I continued on path to success. Unfortunately, I began to reconsider when I discovered that the owner of the company (Charles Torelli) had been busted in New York for fraud, and served some prison time. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
Indoor FM boost with no cables?
On Sun, 27 Jul 2014, Jeff Liebermann wrote:
On Sat, 26 Jul 2014 21:24:11 -0700, (David Platt) wrote: It turned out to be a (famous name) 5-port Ethernet hub, which was leaking its internal clock-oscillator signal into all ports and back into its power supply and was "turning the entire home wiring into a giant antenna" (as the house-wiring-TV-antenna gimmicks used to say, decades ago). Horrid... I could practically hear my spectrum analyzer cringe. Yep. I also know how to shoot myself in the foot. When I replaced the neighbors noisy ethernet switch, he gave me the old switch for recycling. Instead, I threw it into my pile of network boxes for a later autopsy. After about a year, the post-it note marking it as defective was lost. I needed a switch for the local club station, so I grabbed the noisy switch and left. The complaints started about a week later. Oddly, the 2.4GHz link between the repeater building and the club station was the first to suffer interference problems. I think just about every radio on the hill had problems, including the county radios. On the principle of "whatever I did last was probably wrong", I retraced my steps and eventually found the noisy switch. I recall that it was made by Edimax, but don't recall the exact model number. Masking tape is a better choice, it stays on for much longer. As for "turn your house wiring into a giant TV antenna", that was my start in electronics. I recall the ads in the back of Popular Electronics and was intrigued by the principle. I learned that inside the magic coupling box was a "capacitator" and that if one had an AC-DC powered TV, it could be rather dangerous if connected improperly. What got my attention was that it was an obvious fraud, yet also quite successful considering that the ads were everywhere and appeared in every electronics magazine. Instead of the traditional policeman or fireman, I decided to become an electronics crook when I grew up. That was heady stuff for a 9 or 10 year old. My parents grudgingly approved if I agreed to become and engineer first, and later a crook. That seemed reasonable and I continued on path to success. Unfortunately, I began to reconsider when I discovered that the owner of the company (Charles Torelli) had been busted in New York for fraud, and served some prison time. My sister bought one of those phone line antenna things about five years ago. It was new, and obviously junk. I felt so bad that she'd thought it would help. Michael |
Indoor FM boost with no cables?
On 7/26/2014 10:51 PM, Lostgallifreyan wrote:
amdx wrote in : I've* calculated a 6 inch loop made with a #12 or #14 wire will resonate the FM band with a cap between 6.5pf and 10pf. Roughly! Now, I'll see if I can generate the gumption in the next couple of days to build it to see if it has any positive effect. I hope someone beats me to it. With an AM loop and radio the signal couples to the internal loop very well, I don't know how well you can couple a signal into an FM radio. Mikek * actually I used a couple of online calculators. http://www.deephaven.co.uk/lc.html http://www.daycounter.com/Calculator...lculator.phtml This is nice because it beats the issue with two ways to be selective. Even so, I have to have one last shot at the broadband notion: could a 6dB boost with one of those MAR6-based antenna amps be worth a shot? Driving a local diple, taped to a doorframe perhaps, in the centre of the flat? Given the tiny size of those IC's I doubt the amount of power getting out of the flat will be a nuisance, especially given its reluctance to allow RF in (except through the celing, and a dipole taped vertically to a doorframe isn't going to send a lot upwards either.. To some extent the business may be eased by the fact that the two frequencies I'm most keen to get, 91.5MHz and 93.7MHz, aren't far apart. If there is ANY chance this can be solved with no modification or encumbrance to the tiny radio I intend to carry from room to room, that's the way I want to do it. I made a 6 inch loop with a 2pf to 10pf cap, I could see a peak in the loop where I adjusted it to, but it was very low Q and when I started dangling it around my radio I couldn't hear any change. It may take a slightly smaller loop, I had my cap set at minimum to get it to tune the low end of the band. In my mind the experiment failed. I have had loads of fun with AM band loops with high Q and obvious effect on reception. Mikek --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com |
Indoor FM boost with no cables?
Michael Black wrote in
news:alpine.LNX.2.02.1407271422560.23911@darkstar. example.org: Masking tape is a better choice, it stays on for much longer. No, no, the stuff dries up, goes yellow, and flakes off like dry paint. :) And electrical tape's got seepage, big time... What realyl soes stick around is the double-sided adhesive foam tape sold for sticking stuff on car dashboards (and HeNe tubes into place, it stands the heat very well), but finding labels that use the same glue is a thing I never solved. I want to, because the stuff would stay put for decades without seepage even if it gets warm or humid. |
Indoor FM boost with no cables?
amdx wrote in :
I made a 6 inch loop with a 2pf to 10pf cap, I could see a peak in the loop where I adjusted it to, but it was very low Q and when I started dangling it around my radio I couldn't hear any change. It may take a slightly smaller loop, I had my cap set at minimum to get it to tune the low end of the band. In my mind the experiment failed. I have had loads of fun with AM band loops with high Q and obvious effect on reception. Thanks for trying though, it's good info. One reason I imagined staying with a dipole is it's close to what already works as standard. A loop for VHF is a niuce idea for the selectivity of tuning and of orientation, but most radios couple VHF to what amounts to a wire, not a magnetic coupling, so my suspicion is that aiming for magnetic coupling won't work so well as a dipole. |
Indoor FM boost with no cables?
On 7/27/2014 3:16 PM, amdx wrote:
On 7/26/2014 10:51 PM, Lostgallifreyan wrote: amdx wrote in : I've* calculated a 6 inch loop made with a #12 or #14 wire will resonate the FM band with a cap between 6.5pf and 10pf. Roughly! Now, I'll see if I can generate the gumption in the next couple of days to build it to see if it has any positive effect. I hope someone beats me to it. With an AM loop and radio the signal couples to the internal loop very well, I don't know how well you can couple a signal into an FM radio. Mikek * actually I used a couple of online calculators. http://www.deephaven.co.uk/lc.html http://www.daycounter.com/Calculator...lculator.phtml This is nice because it beats the issue with two ways to be selective. Even so, I have to have one last shot at the broadband notion: could a 6dB boost with one of those MAR6-based antenna amps be worth a shot? Driving a local diple, taped to a doorframe perhaps, in the centre of the flat? Given the tiny size of those IC's I doubt the amount of power getting out of the flat will be a nuisance, especially given its reluctance to allow RF in (except through the celing, and a dipole taped vertically to a doorframe isn't going to send a lot upwards either.. To some extent the business may be eased by the fact that the two frequencies I'm most keen to get, 91.5MHz and 93.7MHz, aren't far apart. If there is ANY chance this can be solved with no modification or encumbrance to the tiny radio I intend to carry from room to room, that's the way I want to do it. I made a 6 inch loop with a 2pf to 10pf cap, I could see a peak in the loop where I adjusted it to, but it was very low Q and when I started dangling it around my radio I couldn't hear any change. It may take a slightly smaller loop, I had my cap set at minimum to get it to tune the low end of the band. In my mind the experiment failed. I have had loads of fun with AM band loops with high Q and obvious effect on reception. Mikek Hi, Mike - 6 inch circumference, 6 inch diameter, or 6 inch radius. Just clarifying... John |
Indoor FM boost with no cables?
On 7/27/2014 4:35 PM, John S wrote:
On 7/27/2014 3:16 PM, amdx wrote: On 7/26/2014 10:51 PM, Lostgallifreyan wrote: amdx wrote in : I've* calculated a 6 inch loop made with a #12 or #14 wire will resonate the FM band with a cap between 6.5pf and 10pf. Roughly! Now, I'll see if I can generate the gumption in the next couple of days to build it to see if it has any positive effect. I hope someone beats me to it. With an AM loop and radio the signal couples to the internal loop very well, I don't know how well you can couple a signal into an FM radio. Mikek * actually I used a couple of online calculators. http://www.deephaven.co.uk/lc.html http://www.daycounter.com/Calculator...lculator.phtml This is nice because it beats the issue with two ways to be selective. Even so, I have to have one last shot at the broadband notion: could a 6dB boost with one of those MAR6-based antenna amps be worth a shot? Driving a local diple, taped to a doorframe perhaps, in the centre of the flat? Given the tiny size of those IC's I doubt the amount of power getting out of the flat will be a nuisance, especially given its reluctance to allow RF in (except through the celing, and a dipole taped vertically to a doorframe isn't going to send a lot upwards either.. To some extent the business may be eased by the fact that the two frequencies I'm most keen to get, 91.5MHz and 93.7MHz, aren't far apart. If there is ANY chance this can be solved with no modification or encumbrance to the tiny radio I intend to carry from room to room, that's the way I want to do it. I made a 6 inch loop with a 2pf to 10pf cap, I could see a peak in the loop where I adjusted it to, but it was very low Q and when I started dangling it around my radio I couldn't hear any change. It may take a slightly smaller loop, I had my cap set at minimum to get it to tune the low end of the band. In my mind the experiment failed. I have had loads of fun with AM band loops with high Q and obvious effect on reception. Mikek Hi, Mike - 6 inch circumference, 6 inch diameter, or 6 inch radius. Just clarifying... John Diameter. Five minutes with these calculators and you can pick your own dimensions. http://www.deephaven.co.uk/lc.html http://www.daycounter.com/Calculator...lculator.phtml Mikek --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com |
Indoor FM boost with no cables?
Lostgallifreyan wrote in
: This is nice because it beats the issue with two ways to be selective. Even so, I have to have one last shot at the broadband notion: could a 6dB boost with one of those MAR6-based antenna amps be worth a shot? Driving a local diple, taped to a doorframe perhaps, in the centre of the flat? Given the tiny size of those IC's I doubt the amount of power getting out of the flat will be a nuisance, especially given its reluctance to allow RF in (except through the celing, and a dipole taped vertically to a doorframe isn't going to send a lot upwards either.. To some extent the business may be eased by the fact that the two frequencies I'm most keen to get, 91.5MHz and 93.7MHz, aren't far apart. If there is ANY chance this can be solved with no modification or encumbrance to the tiny radio I intend to carry from room to room, that's the way I want to do it. As a possible answer to my own question I can add this: After looking on eBay to see if cheap widgets might be found and suitably coerced, I learned that there are lots of cheal FM transmitters for immediate local use, in nanowatt range for power. Following that up, I discover that in the UK it is legal, as of around 2007, to set up such transmissions for car and home use, and this is a starting point. I know that if a dipole is cut from thicker stock, it is more broadband, has less Q (and must be cut a tad shorter than theory states for an ideal wire). I don't know a lot more than that, especially what results if two frequecies fairly close to each other like 91.5MHz and 93.7MHz are. Apart from objecting to UK govt policy on priciple (no bad thing right now, as it happens..), is there any objection, thought, or advice anyone wants to add to this? If it is an objection, I want a clear reasoning of why. As far as I can tell so far, my original notion looks viable still, so long as I can limit feedback and any emissions not directly matching signals picked up in the first place, and so long as the total power is well within the new legal requirements, which it will be, I want to use as little as possible on the basis of feedback avoidance. (In other news: that specific source of pulsed noise vanished, someone turned it off nearly 48 hours ago, and it has not returned yet. The current problem is purely one of attenuation, too little internal signal to allow clean stereo sound on FM, and it looks like as little as 12dB would easily fix this with no change to the way I use a portable radio.) |
Indoor FM boost with no cables?
On 7/29/2014 2:23 PM, Lostgallifreyan wrote:
Lostgallifreyan wrote in : This is nice because it beats the issue with two ways to be selective. Even so, I have to have one last shot at the broadband notion: could a 6dB boost with one of those MAR6-based antenna amps be worth a shot? Driving a local diple, taped to a doorframe perhaps, in the centre of the flat? Given the tiny size of those IC's I doubt the amount of power getting out of the flat will be a nuisance, especially given its reluctance to allow RF in (except through the celing, and a dipole taped vertically to a doorframe isn't going to send a lot upwards either.. To some extent the business may be eased by the fact that the two frequencies I'm most keen to get, 91.5MHz and 93.7MHz, aren't far apart. If there is ANY chance this can be solved with no modification or encumbrance to the tiny radio I intend to carry from room to room, that's the way I want to do it. As a possible answer to my own question I can add this: After looking on eBay to see if cheap widgets might be found and suitably coerced, I learned that there are lots of cheal FM transmitters for immediate local use, in nanowatt range for power. Following that up, I discover that in the UK it is legal, as of around 2007, to set up such transmissions for car and home use, and this is a starting point. One of us is confused. Do you want a FM transmitter or an amplifier. The FM transmitter will transmit a frequency that your FM receiver will receive, but you need to feed in a source of audio. I know that if a dipole is cut from thicker stock, it is more broadband, has less Q (and must be cut a tad shorter than theory states for an ideal wire). I don't know a lot more than that, especially what results if two frequecies fairly close to each other like 91.5MHz and 93.7MHz are. You won't be able to notice any difference with any antenna you make between 91.5 and 93.7 MHz. Just try to design it for the middle, you probably won't hit it, but it will probably be close enough. Apart from objecting to UK govt policy on priciple (no bad thing right now, as it happens..), is there any objection, thought, or advice anyone wants to add to this? If it is an objection, I want a clear reasoning of why. As far as I can tell so far, my original notion looks viable still, so long as I can limit feedback and any emissions not directly matching signals picked up in the first place, and so long as the total power is well within the new legal requirements, which it will be, I want to use as little as possible on the basis of feedback avoidance. (In other news: that specific source of pulsed noise vanished, someone turned it off nearly 48 hours ago, and it has not returned yet. The current problem is purely one of attenuation, too little internal signal to allow clean stereo sound on FM, and it looks like as little as 12dB would easily fix this with no change to the way I use a portable radio.) |
Indoor FM boost with no cables?
amdx wrote in :
One of us is confused. Do you want a FM transmitter or an amplifier. The FM transmitter will transmit a frequency that your FM receiver will receive, but you need to feed in a source of audio. That could be you. :) Through several posts I mentioned enough detail to cover all bases, but to summarise: An antenna several tens of feet away is picking up good signals, but wired connections to small portable radios often moved between rooms are inconvenient (even dangerous obstacles if lying around in hallways, over furniture, etc). A small FM aerial amplifier built around a MAR-6 IC works to boost the signal for direct connection, but can it also be used to drive a 1/4-wave dipole for the immediate locality? There's little doubt that it is very low power, likely not able to send enough RF out to justifiably annoy anyone (especially given the UK legal allowance of it now), and almost certainly not enough to feed back to the external aerial given how much RF attenuation exists between inside and outside as it is. Anyb excess can be reduced, this is not the problem, the problem is getting enough in the first place. So the question is: can the MAR-6 based aerial amp drive a dipole with a similar power to that had from these new microtransmitters? It's going to see a similar impedance for that intended, so whatever impediment there may be, impedance doesn't seem likely to be a problem. |
Indoor FM boost with no cables?
amdx wrote in :
You won't be able to notice any difference with any antenna you make between 91.5 and 93.7 MHz. Just try to design it for the middle, you probably won't hit it, but it will probably be close enough. Ok. That's how I usually decide a dipole length anyway. (For receiving). What I was unsure of is whether a tiny RF boost that was NOT a tuned circuit might make the distiction important or useful in any way. (As it is, that amp I once built has filters to limit it to UK FM broadcast band anyway). |
Indoor FM boost with no cables?
Lostgallifreyan wrote in
: A small FM aerial amplifier built around a MAR-6 IC works to boost the signal for direct connection, but can it also be used to drive a 1/4-wave dipole for the immediate locality? I found that old amp and a 1mH choke and 12VDC source so I tried it. The answer is NO. Radiated power is so tiny that I think it would take a 5 grans bit of test gear to analyse why in meaningful detail. I saw no difference whether the power was on or off. The quickly-cobbled dipole itself was fine, even as an indoor aerial wired directly to the input of an AR-3000 it was excellent, nearly as good as outside, but it's the wires I want to avoid, eventually..... If I feel like trying again it will be with one of those legal microtransmitters sometime, just the RF gain part, and probably with the indoor radiating dipole horizontal to reduce coupling to the vertical one outside. |
Indoor FM boost with no cables?
On 7/29/2014 10:58 PM, Lostgallifreyan wrote:
Lostgallifreyan wrote in : A small FM aerial amplifier built around a MAR-6 IC works to boost the signal for direct connection, but can it also be used to drive a 1/4-wave dipole for the immediate locality? I found that old amp and a 1mH choke and 12VDC source so I tried it. The answer is NO. Radiated power is so tiny that I think it would take a 5 grans bit of test gear to analyse why in meaningful detail. I saw no difference whether the power was on or off. The quickly-cobbled dipole itself was fine, even as an indoor aerial wired directly to the input of an AR-3000 it was excellent, nearly as good as outside, but it's the wires I want to avoid, eventually..... If I feel like trying again it will be with one of those legal microtransmitters sometime, just the RF gain part, and probably with the indoor radiating dipole horizontal to reduce coupling to the vertical one outside. The problem with what you're trying to do is you can easily get RF feedback between the output antenna and the input antenna, causing oscillations. And those oscillations may not be in the FM band - they may be on an adjacent band (like aircraft, which is just above the FM band). But the amplifier you're trying to use is meant to feed a receiver directly, not another antenna. So output is going to be very low (on the order of microwatts) - much lower than any amplifier which feeds an antenna. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
Indoor FM boost with no cables?
Jerry Stuckle wrote in
: The problem with what you're trying to do is you can easily get RF feedback between the output antenna and the input antenna, causing oscillations. And those oscillations may not be in the FM band - they may be on an adjacent band (like aircraft, which is just above the FM band). That's my main concern, I want it to be well behaved, or it won't happen. It has simple 1-pole LC filters to limit it to the FM broadcast band, but I will leave it intact and not cobble it into another purpose because it's very good at its original intent. If I do experiment further, it looks like the best thing to watch out for is any unexpected oscillation frequencies despite its filters (LPF on input, HPF on output), and deliberately orienting a radiating dipole to minimise feedback. Is it easy (or possible) to catch clues of such bad behaviour while listeing using somethign like a Tecsun PL-390 or other radio using those new DSP IC's? I ask that because they're cheap, easy to get, and fairly consistent, and include a usefully specified signal strength meter. If so, what should I consider to be a warnign sign? But the amplifier you're trying to use is meant to feed a receiver directly, not another antenna. So output is going to be very low (on the order of microwatts) - much lower than any amplifier which feeds an antenna. Agreed. :) I only tried because the last thing I want to do is pollute the spectrum. Start small... |
Indoor FM boost with no cables?
Jerry Stuckle wrote in news:lr9ohj$33f$1@dont-
email.me: But the amplifier you're trying to use is meant to feed a receiver directly, not another antenna. So output is going to be very low (on the order of microwatts) - much lower than any amplifier which feeds an antenna. Small point, but.... Microwatts. Those new legal microstransmitters are said to be in NANOwatt range output, but allegedly work on the distance scales I'm interested in. Microwatts should certainly have worked, but despite the crude test dipole being good (on standard wired reception test anyway), it didn't work for transmitting even a foot or two with the radio's whip parallel to the upper part of it. If nanowatts should have, the MAR-6 looks like driving picowatts, if I'm lucky. :) |
Indoor FM boost with no cables?
On 7/29/2014 8:31 PM, Lostgallifreyan wrote:
amdx wrote in : One of us is confused. Do you want a FM transmitter or an amplifier. The FM transmitter will transmit a frequency that your FM receiver will receive, but you need to feed in a source of audio. That could be you. :) Through several posts I mentioned enough detail to cover all bases, but to summarize: I understood what you are trying to do, but then you through in the FM transmitter and I don't how that will help, unless you use it as designed, but then to change channels you'll need to go to your audio source and change the station. Anyway, keep plugging away, as I listen to WABC in New York on my internet radio, driving my FM transmitter that I receive on a portable radio I carry around while doing my morning routine, part of which is writing a compound sentence while in Florida. :-) Mikek |
Indoor FM boost with no cables?
On 7/30/2014 1:16 AM, Lostgallifreyan wrote:
Jerry Stuckle wrote in : The problem with what you're trying to do is you can easily get RF feedback between the output antenna and the input antenna, causing oscillations. And those oscillations may not be in the FM band - they may be on an adjacent band (like aircraft, which is just above the FM band). That's my main concern, I want it to be well behaved, or it won't happen. It has simple 1-pole LC filters to limit it to the FM broadcast band, but I will leave it intact and not cobble it into another purpose because it's very good at its original intent. If I do experiment further, it looks like the best thing to watch out for is any unexpected oscillation frequencies despite its filters (LPF on input, HPF on output), and deliberately orienting a radiating dipole to minimise feedback. Is it easy (or possible) to catch clues of such bad behaviour while listeing using somethign like a Tecsun PL-390 or other radio using those new DSP IC's? I ask that because they're cheap, easy to get, and fairly consistent, and include a usefully specified signal strength meter. If so, what should I consider to be a warnign sign? But the amplifier you're trying to use is meant to feed a receiver directly, not another antenna. So output is going to be very low (on the order of microwatts) - much lower than any amplifier which feeds an antenna. Agreed. :) I only tried because the last thing I want to do is pollute the spectrum. Start small... 1-pole LC filters won't be narrow enough to limit potential oscillations to the FM band. You'll need much more than that. As for determining whether it is oscillating or not - I wouldn't trust anything short of a good spectrum analyzer. The signal could be anywhere (and changing frequency). A spectrum analyzer will still show it; a receiver won't necessarily. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
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