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GPR-90
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GPR-90
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GPR-90
dave wrote:
You forgot to turn on the BFO. BFO level is frequently too low for demodding SSB hence the need to reduce RF gain. Yep, easy to see from the jpeg that there's a BFO present. I seem to remember having to repair an old KnightKit tube radio that worked OK otherwise - bad capacitor in the BFO. Person I bought it from didn't know what one was so he wouldn't have had any reason to know it wasn't working when he owned it. |
GPR-90
On Tue, 2 Jul 2013, dave wrote:
You forgot to turn on the BFO. BFO level is frequently too low for demodding SSB hence the need to reduce RF gain. No I didn't. It should be a given that you need the BFO. I was making the point that it's one of those radios of the time that didn't have a product detector, so you had to do what all the books said to do. A few years later, most receivers did have product detectors. Indeed, the GPR-90 came along right at the cusp, so you could get an external unit that added a product detector (and I think some extra selectivity) and some really fine tuning. The receiver has the an IF output jack on the back, even has a jack for feeding audio back into the receiver (though the TMC adapter had a built in audio amplifier). Other receivers had similar units. The R388 and the R390 didn't have product detectors, though they are considered some of the best receivers from the time (and perhaps for all time). But with that level of receiver, turning down RF gain wasn't a real issue. I had no problem receiving SSB, even on six meters, on the SP-600 I had forty years ago. ON the other hand, that Hallicrafters S-120A (the transistorized model) that I got in the summer of 1971 had a horribly weak BFO, so by the time I'd attenuated the incoming signal (a pot between the antenna and the receiver), there weren't many signals left strong enough to receive. |
GPR-90
On 07/11/2013 09:38 AM, Michael Black wrote:
On Tue, 2 Jul 2013, dave wrote: You forgot to turn on the BFO. BFO level is frequently too low for demodding SSB hence the need to reduce RF gain. No I didn't. It should be a given that you need the BFO. I was making the point that it's one of those radios of the time that didn't have a product detector, so you had to do what all the books said to do. A few years later, most receivers did have product detectors. Indeed, the GPR-90 came along right at the cusp, so you could get an external unit that added a product detector (and I think some extra selectivity) and some really fine tuning. The receiver has the an IF output jack on the back, even has a jack for feeding audio back into the receiver (though the TMC adapter had a built in audio amplifier). Other receivers had similar units. The R388 and the R390 didn't have product detectors, though they are considered some of the best receivers from the time (and perhaps for all time). But with that level of receiver, turning down RF gain wasn't a real issue. I had no problem receiving SSB, even on six meters, on the SP-600 I had forty years ago. ON the other hand, that Hallicrafters S-120A (the transistorized model) that I got in the summer of 1971 had a horribly weak BFO, so by the time I'd attenuated the incoming signal (a pot between the antenna and the receiver), there weren't many signals left strong enough to receive. I've had a couple R-390As. I used to leave them on 11175 upper with RF gain low, carrier sliced off with 2 or 4 KC mechanical filter by slightly tuning off center, BFO on about 1200 cycles. It was dead quiet unless someone spoke, like dolby FM. It would stay perfectly tuned for days, with the ovens off. I can't afford electricity to waste on old radios. |
GPR-90
On Wed, 3 Jul 2013, Brenda Dyer wrote:
"Michael Black" wrote in message news:alpine.LNX.2.02.1307021228560.22267@darkstar. example.org... I'm sure by your CB handle I've been licensed longer than you, since June of 1872, and the test was a lot harder here in Canada since it wasn't aimed at the beginner. Michael -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Please, share your secret for such longevity. :) You must have learned code directly from Samuel F.B. Morse. ;) Sorry about that. It had to be 1972, since until April of that year, you had to be fifteen or older to get a ham license in Canada. I've never been able to find out if that rule had been there from the beginning or had been added at some later point. When I first read about amateur radio, I'm not sure if it was in Jack & Jill magazine or a magazine for scouting here in Canada, I can't remember whether I was 8 or 9. But right from that point it was something I wanted, but I knew right at that point that I had some years to wait. Then in December of 1971, I'd been a member of the ARRL since April of that year, I read in the paper that the rule about age was being removed. It turned out to come into effect only in April. In May I took the test, failed at receiving code, then took the code test again (we didn't have to take the whole test over) in June, and passed. So if I wasn't the youngest ham at the time, I had to be among the youngest, not much time for someone younger to take the test. Michael |
GPR-90
dave wrote: On 07/11/2013 09:38 AM, Michael Black wrote: On Tue, 2 Jul 2013, dave wrote: You forgot to turn on the BFO. BFO level is frequently too low for demodding SSB hence the need to reduce RF gain. No I didn't. It should be a given that you need the BFO. I was making the point that it's one of those radios of the time that didn't have a product detector, so you had to do what all the books said to do. A few years later, most receivers did have product detectors. Indeed, the GPR-90 came along right at the cusp, so you could get an external unit that added a product detector (and I think some extra selectivity) and some really fine tuning. The receiver has the an IF output jack on the back, even has a jack for feeding audio back into the receiver (though the TMC adapter had a built in audio amplifier). Other receivers had similar units. The R388 and the R390 didn't have product detectors, though they are considered some of the best receivers from the time (and perhaps for all time). But with that level of receiver, turning down RF gain wasn't a real issue. I had no problem receiving SSB, even on six meters, on the SP-600 I had forty years ago. ON the other hand, that Hallicrafters S-120A (the transistorized model) that I got in the summer of 1971 had a horribly weak BFO, so by the time I'd attenuated the incoming signal (a pot between the antenna and the receiver), there weren't many signals left strong enough to receive. I've had a couple R-390As. I used to leave them on 11175 upper with RF gain low, carrier sliced off with 2 or 4 KC mechanical filter by slightly tuning off center, BFO on about 1200 cycles. It was dead quiet unless someone spoke, like dolby FM. It would stay perfectly tuned for days, with the ovens off. I can't afford electricity to waste on old radios. Yeah, after all, your pal, Boy Barry, said that under his plan, electricity costs would necessarily skyrocket. You're both f00kin clown 'tards! |
GPR-90
On Thursday, July 11, 2013 5:48:55 PM UTC-5, dxAce wrote:
dave wrote: On 07/11/2013 09:38 AM, Michael Black wrote: On Tue, 2 Jul 2013, dave wrote: You forgot to turn on the BFO. BFO level is frequently too low for demodding SSB hence the need to reduce RF gain. No I didn't. It should be a given that you need the BFO. I was making the point that it's one of those radios of the time that didn't have a product detector, so you had to do what all the books said to do. A few years later, most receivers did have product detectors. Indeed, the GPR-90 came along right at the cusp, so you could get an external unit that added a product detector (and I think some extra selectivity) and some really fine tuning. The receiver has the an IF output jack on the back, even has a jack for feeding audio back into the receiver (though the TMC adapter had a built in audio amplifier). Other receivers had similar units. The R388 and the R390 didn't have product detectors, though they are considered some of the best receivers from the time (and perhaps for all time). But with that level of receiver, turning down RF gain wasn't a real issue. I had no problem receiving SSB, even on six meters, on the SP-600 I had forty years ago. ON the other hand, that Hallicrafters S-120A (the transistorized model) that I got in the summer of 1971 had a horribly weak BFO, so by the time I'd attenuated the incoming signal (a pot between the antenna and the receiver), there weren't many signals left strong enough to receive. I've had a couple R-390As. I used to leave them on 11175 upper with RF gain low, carrier sliced off with 2 or 4 KC mechanical filter by slightly tuning off center, BFO on about 1200 cycles. It was dead quiet unless someone spoke, like dolby FM. It would stay perfectly tuned for days, with the ovens off. I can't afford electricity to waste on old radios. Yeah, after all, your pal, Boy Barry, said that under his plan, electricity costs would necessarily skyrocket. You're both f00kin clown 'tards! Back on that sauce again, Tonto? |
GPR-90
On Thursday, July 11, 2013 12:41:11 PM UTC-4, dave wrote:
On 07/11/2013 09:38 AM, Michael Black wrote: On Tue, 2 Jul 2013, dave wrote: You forgot to turn on the BFO. BFO level is frequently too low for demodding SSB hence the need to reduce RF gain. No I didn't. It should be a given that you need the BFO. I was making the point that it's one of those radios of the time that didn't have a product detector, so you had to do what all the books said to do. A few years later, most receivers did have product detectors. Indeed, the GPR-90 came along right at the cusp, so you could get an external unit that added a product detector (and I think some extra selectivity) and some really fine tuning. The receiver has the an IF output jack on the back, even has a jack for feeding audio back into the receiver (though the TMC adapter had a built in audio amplifier). Other receivers had similar units. The R388 and the R390 didn't have product detectors, though they are considered some of the best receivers from the time (and perhaps for all time). But with that level of receiver, turning down RF gain wasn't a real issue. I had no problem receiving SSB, even on six meters, on the SP-600 I had forty years ago. ON the other hand, that Hallicrafters S-120A (the transistorized model) that I got in the summer of 1971 had a horribly weak BFO, so by the time I'd attenuated the incoming signal (a pot between the antenna and the receiver), there weren't many signals left strong enough to receive. I've had a couple R-390As. I used to leave them on 11175 upper with RF gain low, carrier sliced off with 2 or 4 KC mechanical filter by slightly tuning off center, BFO on about 1200 cycles. It was dead quiet unless someone spoke, like dolby FM. It would stay perfectly tuned for days, with the ovens off. I can't afford electricity to waste on old radios. My R-390(not A)got drowned in seawater last year, during the storm called Sandy . Now I don't know what to do with it... |
GPR-90
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