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#1
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Hi All,
Anyone recall or have a copy of the articles in Ham Radio, QST, or 73's which has the 455KHz FM detector and the other information for Cb conversion to 10m FM? I recall that Melco did some kits, I recall the article but can not locate it in my library. I believe I saw a FM demodulator either HR or HR Horzion. thanks de KJ4UO. |
#2
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The most practical FM detector, for both fidelity and cost would be a
phase-locked-loop chip... wrote in message oups.com... Hi All, Anyone recall or have a copy of the articles in Ham Radio, QST, or 73's which has the 455KHz FM detector and the other information for Cb conversion to 10m FM? I recall that Melco did some kits, I recall the article but can not locate it in my library. I believe I saw a FM demodulator either HR or HR Horzion. thanks de KJ4UO. |
#3
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#4
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![]() "J. Reed" ) writes: The most practical FM detector, for both fidelity and cost would be a phase-locked-loop chip... Well there was an article in QST by Bob Heil about converting a CB set to FM, I'm pretty sure it was in 1981. As I said here back in 1998: Converting a CB set to FM, once the conversion to the appropriate section of the 10M band has been accomplished, would consist of FM'ing the transmitter (I can't remember, but I assume the articles disable the AM modulation of the final amplifier, and feed some of the audio to the VCO), and adding an FM detector to the receiver. The two articles I can remember used IC detectors, which would add some IF amplification and limiting before the detector. One thing worth considering is that you can easily scrounge up a 455KHz FM IF strip from a cordless phone, or a 49MHz superhet walkie talkie. I wouldn't say fidelity is an issue here, given that it's narrow deviation we are talking about and that's not a problem to get a linear discrimator. YOu probably will get a better results with a full FM IF strip, and those are really easy to pull from various things, either just the IC (any old TV set will have one for the sound demodulator, at least in North America), or for that matter any FM "stereo receiver", or as a full IF strip. The advantage of the latter is that the discrimator is already aligned, and you get not only the demodulator IC but the needed IF transformers and FM-bandwidth filter(s). You can find such strips in cordless phones (I found some a few weeks ago that were for 2.4GHz, and they still had defineable IF strips with 10.7MHz and then 455KHz conversions), or those 49MHz walkie talkies, or older cellphones (which have the advantage of being cheap and don't have high integration in the ICs). I've never found a scanner in the garbage, but they too would have such IF strips. Even commercial 2-way equipment had such IF strips, and even recent ones may (though since I'm not familiar with recent equipment I don't know if they are still going down to 455KHz.) Michael VE2BVW wrote in message oups.com... Hi All, Anyone recall or have a copy of the articles in Ham Radio, QST, or 73's which has the 455KHz FM detector and the other information for Cb conversion to 10m FM? I recall that Melco did some kits, I recall the article but can not locate it in my library. I believe I saw a FM demodulator either HR or HR Horzion. thanks de KJ4UO. |
#5
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Use a Motorola MC3357 or MC3359 IC for the FM rcvr section...you can easily
put in in the 1st IF of the CB and get FM detection as well as noise squelch (while the AM CB uses level or S meter squelch)..I do have a HyGain 16 on 10FM with a true FM scanner IF in it ...worked great. Chris WB5ITT wrote in message oups.com... Hi All, Anyone recall or have a copy of the articles in Ham Radio, QST, or 73's which has the 455KHz FM detector and the other information for Cb conversion to 10m FM? I recall that Melco did some kits, I recall the article but can not locate it in my library. I believe I saw a FM demodulator either HR or HR Horzion. thanks de KJ4UO. |
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