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#2
June 5th 06, 07:53 AM
posted to rec.radio.shortwave
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Sherwood SE-3 MK III D Synchronous High-Fidelity Phase-Locked AM Product Detector
Telamon wrote: In article .com, wrote: Telamon wrote: In article , (Michael Black) wrote: HFguy ) writes: Joe Analssandrini wrote: John Plimmer wrote: There was also a long thread on this newsgroup that claimed the AOR 7030 had the best sync detector in the business, but I still punt the R8B as the 7030 sync was NOT sideband selectable, which is required for most good listening. Dear John, Contrary to what you write, the AR7030's synchronous detection circuit IS most definitely sideband-selectable and features double-sideband detection as well (so does the Drake R8B). It does not feature a "fixed" sideband selection as does the Drake R8B (or the Drake SW8/Grundig Satellit 800), but rather a "variable" one using the passband tuning. (You can tune the circuit this way as well on the Drake.) If your description (above) is technically accurate, the 7030 does not have a 'real' sideband sync' detector because it requires using the passband tuning to select the desired sideband in the double-sideband mode. The sideband sync' detector on the R8B uses phase cancellation for rejecting the unwanted sideband. This is a more effective rejection method than using only passband tuning. But are you arguing semantics, or outcome? Because the phasing method of selectable sideband reception is not as good as the filter method. A filter really knocks out the unwanted sideband, while the phasing method tends to give far less rejection of the unwanted sideband. It is not a semantics argument. On the R8B you can pick the side band to listen to and tweak the passband. Often if I am bother by a heterodyne or splash from an adjacent channel I can pick the opposite sideband and the interference is GONE. The AOR7030+ can't do that. When you go for one sideband, you need to select a narrower filter (technically half the bandwidth). This works just fine on the 7030+, used with passband tuning. Also, the 7030 VFO is so steady you can pick USB or LSB, then zero beat it. This works on shortwave, but seems to add a flutter to AM BCB. The Sherwood for sale on ebay may not be functional or in good working shape as it is being sold from a drop off site rather than the user. I have no problem passing on this sale. Usually the passband tuning is all I need to get rid of adjacent channel interference and the AOR7030+ and Drake R8B both have this ability. A neat thing the AOR can do is auto notch a heterodyne tone. Additionally the AOR will track this tone and keep it notched out if it drifts. The Drake has a manual notch that is pretty sharp. I usually don't have to do this because moving the passband usually solves the problem but I have had the situation where I have splash on one side a heterodyne tone from another station on the other sideband so both functions are needed. The AOR 7030+ can auto tune itself to a station and maintains lock on it without intervention and it has the auto notch feature the Drake does not have where the Drake has the sideband selectable sync. Every radio has its pluses and minuses and will work better in some situations, is easier to use, or sound better than other radios. -- Telamon Ventura, California I use the notch filter quite often, but unless things have changed, it was an option on the radio. By the time you outfit a 7030 with all the goodies, it costs much more than the Drake R8B did. I never found the noise blanker to be all that useful on the 7030, but it might just be me. |
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#3
June 5th 06, 08:08 AM
posted to rec.radio.shortwave
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Sherwood SE-3 MK III D Synchronous High-Fidelity Phase-Locked AM Product Detector
In article . com,
wrote: Telamon wrote: In article .com, wrote: Telamon wrote: In article , (Michael Black) wrote: HFguy ) writes: Joe Analssandrini wrote: John Plimmer wrote: There was also a long thread on this newsgroup that claimed the AOR 7030 had the best sync detector in the business, but I still punt the R8B as the 7030 sync was NOT sideband selectable, which is required for most good listening. Dear John, Contrary to what you write, the AR7030's synchronous detection circuit IS most definitely sideband-selectable and features double-sideband detection as well (so does the Drake R8B). It does not feature a "fixed" sideband selection as does the Drake R8B (or the Drake SW8/Grundig Satellit 800), but rather a "variable" one using the passband tuning. (You can tune the circuit this way as well on the Drake.) If your description (above) is technically accurate, the 7030 does not have a 'real' sideband sync' detector because it requires using the passband tuning to select the desired sideband in the double-sideband mode. The sideband sync' detector on the R8B uses phase cancellation for rejecting the unwanted sideband. This is a more effective rejection method than using only passband tuning. But are you arguing semantics, or outcome? Because the phasing method of selectable sideband reception is not as good as the filter method. A filter really knocks out the unwanted sideband, while the phasing method tends to give far less rejection of the unwanted sideband. It is not a semantics argument. On the R8B you can pick the side band to listen to and tweak the passband. Often if I am bother by a heterodyne or splash from an adjacent channel I can pick the opposite sideband and the interference is GONE. The AOR7030+ can't do that. When you go for one sideband, you need to select a narrower filter (technically half the bandwidth). This works just fine on the 7030+, used with passband tuning. Also, the 7030 VFO is so steady you can pick USB or LSB, then zero beat it. This works on shortwave, but seems to add a flutter to AM BCB. The Sherwood for sale on ebay may not be functional or in good working shape as it is being sold from a drop off site rather than the user. I have no problem passing on this sale. Usually the passband tuning is all I need to get rid of adjacent channel interference and the AOR7030+ and Drake R8B both have this ability. A neat thing the AOR can do is auto notch a heterodyne tone. Additionally the AOR will track this tone and keep it notched out if it drifts. The Drake has a manual notch that is pretty sharp. I usually don't have to do this because moving the passband usually solves the problem but I have had the situation where I have splash on one side a heterodyne tone from another station on the other sideband so both functions are needed. The AOR 7030+ can auto tune itself to a station and maintains lock on it without intervention and it has the auto notch feature the Drake does not have where the Drake has the sideband selectable sync. Every radio has its pluses and minuses and will work better in some situations, is easier to use, or sound better than other radios. -- Telamon Ventura, California I use the notch filter quite often, but unless things have changed, it was an option on the radio. By the time you outfit a 7030 with all the goodies, it costs much more than the Drake R8B did. I never found the noise blanker to be all that useful on the 7030, but it might just be me. I bought the AOR7030+ plus with options and it cost more than the Drake R8B. -- Telamon Ventura, California |
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