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Sony ST80W AM/FM Stereo Tuner
Upon
removing its cover, I felt like a Fabergé disassembling
some tiny equivalent to a Cathedral style floor standing radio
from the 1930's, perhaps like my Stromberg-Carlson. The Sony
ST80W has all of the elements of that cathedral radio, perhaps
most specifically, a round tuning dial that suggests a vernier,
even if it isn't. The Sony may be miniature by comparison to
the Stromberg, but it is not specifically so, and Sony put some
large pieces into the box, most notably a front end tuning capacitor
for the AM tuner that made me weep for joy, so well conceived
it is.
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FM Tuner
I don't know if I would care to make the claim for the
FM tuning capacitor. It is part of a highly miniaturized
unit that includes all of the front end circuitry. The
entire assembly is smaller than the compact front end
that Scott used in the 344. You could squeeze four of
these assemblies into the tuning cap cover off a 312.
It is small. I wasn't prepared to take the module apart
to see how Sony did it. Perhaps if a wrecked Sony receiver
from the same time period comes along, I will investigate.
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Sony uses an intricate mechanism to drive the separate front
end capacitors from a weighted tuning knob. The setup has held
up well, considering the imprecision of a pulley when taking
both frequency ranges into account. Dial miscalibration was
the same from band to band, suggesting that the intricate mechanism
was holding the two front ends in the same position with respect
to the band. But all points are moot, because I could find no
adjustment points for the calibration. In fact, this tuner is
pretty much a come as you go proposition. I challenge a technician
to align one.
This turned out to be unfortunate, for the multiplex circuit
has stopped functioning, most likely because it isn't receiving
a clean 19 kHz signal to lock on to. This type of problem is
not uncommon with a 35 year old tuner, but the lack of any sort
of tuneability to the i.f. circuit, at the very least the detector
or discriminator circuit, it is game over for FM Stereo. Having
said that, I should say that when this tuner functioned at its
peak, it provided the type of FM performance that placed it
in the top rank of tuners. No working stereo makes it hard to
compare against other tuners, but my knowledge of the tuner
informs me that it sits very well in the company of the Advent
300 or the Magnum Dynalab, but is closer on the continuum to
the Scott 310E than either of those tuners are. I am not talking
about signal sleuthing here, but instead, am concerned with
sound. The Advent and the Magnum Dynalab have bass and treble
distortions that are absent in a Scott 312, or even a modest
330C, as Robert 'The King of Scott' and I recently discovered.
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Twenty or so years ago I did
some DX tests on this tuner and formed a deep impression
about its ability to retrieve signals from two relatively
distant (about 90 miles) broadcast areas. The stations that
I was attempting to receive using a folded dipole antenna
included CBC 93.5 FM in Montreal, and CHEZ 106.1 FM in Ottawa.
Both stations came in without hesitation, a nice clear signal
with fairly quiet stereo. While I am certain than all of
the tuners that I prize would have done well, and some would
have done exceptionally well in this test milieu, I suggest
that the Sony is capable of hanging in with the better FM
tuners and my discovery that over the decades the particular
one that I have has little future as a stereo tuner due
to age is no indication of a lack of quality. Just remember
your stereo caveats when it comes to FM tuners that are
designed around non adjustable crystal circuits. Scott and
Heathkit both used crystal circuits that can be adjusted,
and Scott continued to use ratio detectors with adjustable
transformers until it ran out of parts. |
AM Tuner
| When the ST80W was new, its contenders
on AM performance must have been few, and I suppose that
your average 10B or REL owner would have a ST80W for its
stellar AM tuner. Even after 35 years it is clear and reasonably
ignition free. Only the AM tuner in my Scott 367 (or the
357 for that matter) ousts it for rejection. One glance
at the tuning capacitor that makes up the tunable portion
of the unit knows that Sony took AM performance seriously.
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The capacitor is shown at approximately 100 per cent of its
size. A large portion of the cabinet's interior is occupied
by the capacitor. It is as large as the unit that Scott used
in its 330 and it is of superior finish. The Scott 330D tuner,
perfectly set up, sounds about as good as the Sony, and with
its greater dedication to notch filtering, Scott's designs into
solid state were more advanced in application.
Construction
Sony's approach to packaging is universal, adapting to shape
on all sides to hold two front ends, a pair of circuit boards
(one is for the multiplex) and the power supply. It is an example
of box chassis construction. Scott utilized box construction
on lab equipment and, starting in late 1965, in the 342. Sony
applied it to a whole range of compact products, including the
cassette tape recorder. In fact, the most famous of all institutional
tape recorders, the TC110, was a contemporary of the ST80W.
The TC110 was the first tape recorder to exceed the performance
characteristic of the definitive model from Philips, first marketed
in 1964. My guess is that the ST80W was released in 1968 as
the tuner portion of a posh modular system. When you look inside,
you see the classic Sony style and quality that set it apart
from its rivals.
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