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#21
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Check out this guys site. He builds everything from scratch and
shows schematics for exaclty what you asked about, including 3 transistor SSB transceivers!!! http://www.intio.or.jp/jf10zl/index.html He has FM, SSB and AM transceivers for various bands and must be the King of homebrew. phil - N4GWV I am looking for a simple -- as in not too much more complex than a Pixie -- schematic for a 2m or 6m FM transmitter or transceiver. Anyone know where I can find one that's low-cost and suitable for a beginner to build, if such a thing exists? |
#22
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Phillip Jockell wrote in message ...
Check out this guys site. He builds everything from scratch and shows schematics for exaclty what you asked about, including 3 transistor SSB transceivers!!! http://www.intio.or.jp/jf10zl/index.html i have seen this site a number of times and spent some time reviewing it in detail. his designs are pretty simple. and i would say, too simple to be replicated and used. for instance, he has a transceiver with 50mW output. while this might be a good experiment, don't expect to work all the grids using this one. similarly, his receivers (like the one SSB transceiver with three transistors) might work across the lab bench. but it will hardly suffice as the main rig in a station. in anycase, i think we are past the point of measuring rig complexities with the number of active devices. these days the active devices often cost less than some passive components. I get decent RF low power transistors for less about 3 cents each. This week, i finished an 2M transceiver too (The schematics are still being drawn out, i will post the circuit soon.) It uses (i just counted) 19 transistors, two ICs and two diodes. The total cost of material is still less than 10 dollars (at least in india). Quite often, using active devices often reduces the cost rather than increasing it. For instance, a phasing type of SSB transceiver cost far less than a single collins mechanical filter. Yet, the performance is as good if not better than a that of a filter type ssb generator and all most all circuit complexity is at audio frequencies. too often, we tend to look for the simplest (read least active device count) system only to find that it doesn't work as advertised. It is more likely that a slightly more complex circuit turns out to be more stable and easier to get going that the least count winner. easy replication of a design means that if you build it again, you should expect the same performance. this usually means that you extract a little less out of each stage than it is capable of leaving some head-room for device variation and component value tolerance. That is the reason why many of us here like to reuse certain blocks (like broad-band feedback amplifiers) over and over again. finally, i would say, that it is not enough (at least for me personally) to build something that makes a contact across the city. one should aspire for the best quality in terms of whatever your personal design goals are. Often, unrestricted by the need to include all the features (like multiband, PLL, etc.) and with the ability to use one off components, the amateur can spend more effort in building and aligning his rig that a commercial counterpart. That is a goal worth acheiving. it is not enough to match a commercial rig in terms of performance, it is just a moderate challenge to build something that that surpasses it by your own criterion. |
#23
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Phillip Jockell wrote in message ...
Check out this guys site. He builds everything from scratch and shows schematics for exaclty what you asked about, including 3 transistor SSB transceivers!!! http://www.intio.or.jp/jf10zl/index.html i have seen this site a number of times and spent some time reviewing it in detail. his designs are pretty simple. and i would say, too simple to be replicated and used. for instance, he has a transceiver with 50mW output. while this might be a good experiment, don't expect to work all the grids using this one. similarly, his receivers (like the one SSB transceiver with three transistors) might work across the lab bench. but it will hardly suffice as the main rig in a station. in anycase, i think we are past the point of measuring rig complexities with the number of active devices. these days the active devices often cost less than some passive components. I get decent RF low power transistors for less about 3 cents each. This week, i finished an 2M transceiver too (The schematics are still being drawn out, i will post the circuit soon.) It uses (i just counted) 19 transistors, two ICs and two diodes. The total cost of material is still less than 10 dollars (at least in india). Quite often, using active devices often reduces the cost rather than increasing it. For instance, a phasing type of SSB transceiver cost far less than a single collins mechanical filter. Yet, the performance is as good if not better than a that of a filter type ssb generator and all most all circuit complexity is at audio frequencies. too often, we tend to look for the simplest (read least active device count) system only to find that it doesn't work as advertised. It is more likely that a slightly more complex circuit turns out to be more stable and easier to get going that the least count winner. easy replication of a design means that if you build it again, you should expect the same performance. this usually means that you extract a little less out of each stage than it is capable of leaving some head-room for device variation and component value tolerance. That is the reason why many of us here like to reuse certain blocks (like broad-band feedback amplifiers) over and over again. finally, i would say, that it is not enough (at least for me personally) to build something that makes a contact across the city. one should aspire for the best quality in terms of whatever your personal design goals are. Often, unrestricted by the need to include all the features (like multiband, PLL, etc.) and with the ability to use one off components, the amateur can spend more effort in building and aligning his rig that a commercial counterpart. That is a goal worth acheiving. it is not enough to match a commercial rig in terms of performance, it is just a moderate challenge to build something that that surpasses it by your own criterion. |
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