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Post by timberwolf1217 on Apr 23, 2015 21:53:57 GMT -5
i just purchased a superstar 120fm.i had one of these radios years ago but i cant remember the output wattage.i seem to remember it being an unusual board.any ideas what i should expect or any good output mods?a variable key would be nice
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Post by BBB on Apr 24, 2015 13:21:09 GMT -5
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Sandbagger
Administrator/The Boss 
Posts: 6,247 
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Post by Sandbagger on Apr 24, 2015 18:24:19 GMT -5
There seems to be a few different versions with different channel ranges depending on the country used. The most common version is 120 channel with a normal CB band, and then a drop band (26.515-26.955) and an upper band (27.415-27.855). The PLL is the very unmodifiable, 40 channel-only UPD-2816. The bands are controlled by changing the loop mixer crystal. It has a 2SC-1307 for a final, so a 10 watt output is likely on high power, but with only the usual TA7222 audio chip driving it, I'd be skeptical of getting the full 100% modulation out of it at 10 watts of carrier. Based on the schematic I saw, this was an AM-only radio. So the version with FM as well, may have some other differences in circuitry. |
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Post by BBB on Apr 24, 2015 18:51:52 GMT -5
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Post by timberwolf1217 on Apr 24, 2015 18:59:14 GMT -5
OK.thanks for the info.waiting on it to get sent to me.it is the model with FM.the last one I owned had a wire wound resistor in the output circuit.its the only radio I have seen with that configuration.a local tech removed the resistor and added variable key.idk what all he did to the circuit but it performed well.seems like it keyed about a watt and swung about 15 on a dosey.any way to increase the modulation?
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Sandbagger
Administrator/The Boss
Posts: 6,247
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Post by Sandbagger on Apr 24, 2015 21:00:40 GMT -5
OK.thanks for the info.waiting on it to get sent to me.it is the model with FM.the last one I owned had a wire wound resistor in the output circuit.its the only radio I have seen with that configuration.a local tech removed the resistor and added variable key.idk what all he did to the circuit but it performed well.seems like it keyed about a watt and swung about 15 on a dosey.any way to increase the modulation? Keeping your dead key low will increase your modulation. Whatever you do, don't clip the modulation limiter. That'll just make it splatter. |
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Sandbagger
Administrator/The Boss
Posts: 6,247
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Post by Sandbagger on Apr 24, 2015 21:11:18 GMT -5
The radio is a 120 channel unit. In this particular version (which does not have FM) the "Hi" channel position does cover part of the 10 meter band, starting at 28.500. It makes no sense since it does not cover anything between channel 40 and 28.500. Covering that part of the 10 meter band is kind of silly since AM is usually found at 29.000 and up. But I guess it all depends on which country the radio is made for. The ones I've seen in the U.S., have the normal 40, a "down 40" and an "up 40" band. But that can all be changed based on what frequency crystals you have in the loop mixer. |
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Post by timberwolf1217 on Apr 24, 2015 22:47:48 GMT -5
The one I had before and the one I got coming both have FM.they have one band below and one band above the regular 40.thanks for the help gentlemen
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