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Robert Morein
 
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Default 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.


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Arny Krueger
 
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Default 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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Arny Krueger
 
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Default 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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