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60's Solid State V.S. 70' Solid State Tuners
"Bryan Dibble" wrote in message m... I own a top-end model ( back then) Zenith 26 " T.V, with A.M & F.M, Turntable Console and a mid 70's Kenwood Eleven model reciever. Why is the tuner portion of the Kenwood so small (and held in high esteem by some) and the tuner in the Zenith mammoth in comparison? Did technolgy advance that much in just 5 to 7 years? Or is the older Zenith a better tuner? Thank you all for any input on this matter. Sincerely, Bryan Dibble The technology did, indeed, advance remarkably. Your Kenwood has a couple of IC's that replace multiple stages of IF amplification, and it has a little chip called a phase-locked-loop, with about 40 transistors on it, that was a technological marvel at the time. |
#2
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60's Solid State V.S. 70' Solid State Tuners
"Bryan Dibble" wrote in message
m I own a top-end model ( back then) Zenith 26 " T.V, with A.M & F.M, Turntable Console Ca. 60's Zenith audio was pretty grim, as a rule. and a mid 70's Kenwood Eleven model receiver. By the mid-70s Kenwood (Trio) solid state receivers were pretty highly developed. Why is the tuner portion of the Kenwood so small (and held in high esteem by some) and the tuner in the Zenith mammoth in comparison? In the 60's, tuners were based on air-dielectric tuning capacitors which were physically large. They generally had a goodly number of IF transformers, which were fairly large taken together. There were very few if any integrated circuits. For example, a multiplex decoder could be composed of up to a dozen discrete transistors and diodes, as well as a number of transformers and coils/ In the mid-late 70's, tuners were based on varacter tuning capacitors which were tiny diodes. They generally had one or two ceramic or crystal filters for IF selectivity, which were also generally smaller than IF transformers. There was heavy use of integrated circuits. A multiplex section could be reduced to a single tiny integrated circuit, and it would outperform the larger discrete version. An anecdote. I had a ca. 1966 Heath AR-15 receiver with a complex FM stereo decoder with about a dozen transistors and diodes, and at least a half-dozen coils and transformers. It required constant adjustment. The next generation of Heath receivers used a single integrated circuit that performed better, and required vastly fewer associated parts. I retrofitted the next-generation chip to the AR15, which greatly enhanced its performance and ease-of-use. Did technology advance that much in just 5 to 7 years? It could. There were still some retrograde receivers in production 5-7 years later. Or is the older Zenith a better tuner? I doubt it. As a rule Kenwood (Trio) receivers had better-than-average FM sections, even in the days of tubes. Sometimes their FM sections outperformed the amplifier sections, as compared to competitive receivers. There was one Kenwood tubed receiver that had a great FM stereo section, but sonically horrific 17 wpc power amps. |
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60's Solid State V.S. 70' Solid State Tuners
"Sam Byrams" wrote in message
om I would rather have a good well-driven variable cap or a PTO than an analog varactor arrangement. It resonates well emotionally. My best tuner is a Pioneer TX 9100 which has a real tuning cap. Varactors were used with a geared pot to produce a DC voltage that swung the LO, I think the GE Superadio III (sic) still does, but it's not that stable. Today, they're almost all driven by digital circuitry. The old Collins and Racal HF receivers were very stable and pretty accurate, and even at VHF this can work well. HP used the tuned cavity LO in its classic 8640B generator-doesn't everyone own one?-and this works even slicker. Even though frequency readout is with a counter, the generator is fully analog and, once warmed up, very stable. And has-like many analog receivers-negligible phase noise. No PLLs in the signal path! Is that supposed to be the good news or the bad news? Years ago someone actually showed off a FM tuner-actually a full general purpose comm grade receiver from 30 to 250 or so MHz-with the tuned cavity out of a surplus 8640 for variable tuning, an OCXO, and the spectrum/scope out of a Motorola or HP service monitor. Beats hell out of that 6E5 on the Magnum Dynalab-apparently a consumer clock radio front end in an expensive milled anodized case-doesn't it? Frankly, I don't see a lot of future in perfectionist analog FM receivers. |
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