Pioneer
TX-7800 Stereo FM/AM Tuner with Servo-Lock / Touch-Sensor Tuning.
Significant
Improvements in Accuracy Fidelity and Convenience
Features
Servo-Lock /
Touch-Sensor Tuning – Drift-free performance and ease of use with unique FM
station selection system.
Servo
Re-Lock Included – Selkected stations is re-locked when you re-the tuner.
Pioneer
“Clean Design” - High S/N ratio and low distortion in FM stereo.
Selectable
AM IF Bandwidth – You choose Wide or Narrow for better AM sound in any
reception situation.
High
Sensitivity / Stability – Enjoy true high fidelity performance every time.
Sensitivity is a high 9,3 dBf (1,6 uV).
FINGERTIP
TUNING CONTROL
Pioneer's
Servo-Lock Tuning for FM
Three important criteria were included in the
design concept drafted by Pioneer for this attractively -priced stereo FM/AM
tuner. First was high tuning accuracy – station-pulling capability in any
reception circumstances is the least we can offer customers who look to us for
state-of-the-art performance. Superior high fideelity tonal quality and
improved tuning convenience were also on the list. Our engineers developed the
unique Stereo-Lock/Touch Sensor system featured here so that all three demands
are fully met. Here's how it works
Touch to
Tune, Let Go to Lock
When you
tune an FM station, simply follow these easy steps:
Step 1 –
Grip the special Touch Sensor tuning knob as you would any other tuning
control. The difference here is that the built-in Servo-Lock circuitry in the Pioneer TX-7800
is turned Off the instant your fingers make contact. As they do, the Locked
indicator goes Out.
Step 2 –
Tune in the FM station you desire, observing the Twin Tuning Meters and the
dial pointer.
Step 3 –
Now, remove your fingers from the knob. The Servo-Lock is immediately put back
in the On mode and your station is accurately, stably locked in until you
intentionally de-tune it for another selection.
To confirm
this, observe the green LED in the dial panel. When you are on-station, it
lights to indicate Locked status.
By the way,
if the station you have tuned in stereo, the Stereo indicator lights in red.
It, too, is an LED which can never burn out. And on the rear panel of the
TX-7800 is a selector for High or Low sensitivity for the Touch-Sensor itself
to accommodate the tuning knob to your particular touch.
How
Pioneer's Servo-Lock Ends Drift.
Absolutely
no changes of temperature, humidity or other environmental factors can cause
the drift or de-tuning of an FM station once you,ve locked it in. this
“miracle” of technology is not so difficult to understand when our tuning
circuitry is examined in depth, as follows:
first, the
signal enters the FM antenna and is passed on to the mixer stage where it meets
the output of the local oscillator.. if the station ypu have selected is, say,
100MHz, the local oscillation frequency is 110,7 MHz to meet the 10,7 MHz IF
frequency in the next stage. Now lets say the local oscillator frequency drifts
+100kHz. The IF frequency will then vary to 10,8 kHz and the results will show
up in the output of the discriminator transformer in an “S” mcurve. That
difference is rectified into DC voltage, and detected and fedback to the local
oscillator through a varicap. Immediatel, the local oscillation frequency is
shifted down to resume the correct 10,7 MHz for accurate reception of the
selected station , Locked reception.
The beauty of the system is that it is
oolproof. Like the high-precision servo-systems used in computers, it uses
error to correcterror – all so fast your ears can detect no error at all.
Automatic
Re-Lock System, Too
The accuracy
of the Servo-Locksystem in the TX-7800 is unfailing, even when you power-off
the tuner. When power is restored, the previously selected station is instantly
Re-Locked. Tape buffs will note that this is a definite plus when using the
tuner with a pre-set timer clock for unassisted off-the-air recording.
Improvrd
Tuning Aids
You'll
appreciate the new design of the scales used for the Twin Tuning Meters. We've
used s strsight-line format for easier reading, and long-throw needles for more
indication margin. The scales are in brilliant blue to match the quick-response
fluorescent peak/Average meters on the latest Pioneer tape decks and SA
integrated amps. The meter on the left is for Signal strength for FM and AM
broadcasts; on the right is the Tuning meter for center-of-channel tuning for
FM.
ADVANCED FM
CIRCUITRY
Beautiful
Tonal Quality is Assured
Superior
high fidelity tonal quality was on our list of design criteria along with
tuning accuracy and tuning convenience. We've
found answers to the challenges of providing a high S/N ratio, lower
distortion and high stereo separation in the TX-7800 in order to deliver that
tonal quality without compromise. Along with these hi-fi musts, our advanced
circuitry also provides the high sensitivity, high spurious response ratio,
high image response ratio and other specifications requiredfor the elimination
of all forms of interference. Tonal quality is optimized under any reception
conditions – from too-weak and too-strong stations alike. Audiophiles will be
interested in the details, and here they are.
Sophisticated
FM Front End with MOS FET
A low-noise,
dual-gate type MOS FET is employed in the FM front end of the TX-7800. It has
superior cross modulation characteristics that is responsible for the high
sensitivity and high interferenc rejection capability in FM reception. Proof is
in the specs -9,3 dbF usable sensitivity, 100 dB IF response ratio, 85 dB image
response ratio and 95 dB spurious response ratio.
The MOS FET
work with an elaborate frequency-linear 4-gang variable capacitor and the above
mentioned Servo-Locksystem to assure stable tuning accuracy at all times.
Three
Phase-Linear Ceramic Filters in FM IF
Integrated
circuitry empoloying the latest microelectronic techniques is very popular
among Pioneer engineers for a number of very good reasons. They offer, for
instance, higher accuracy and higher dependability than discrete parts in most
situations. Not incidentally, lower production costs and a much lower incidence
of costly repair are also on the list of advantages offered by ICs.
In the FM IF
section of the TX-7800, two high-gain iCs are employed as differential type IF
amps. They are deployed with no fewer than three phase-linear ceramic filters
to further improve interference rejection characteristics. FM alternate channel
selectivity, for example, is an excellent 75 dB.
New
Quadrature Discriminator
A
Pioneer-developed IC, the PA-3001A which is found only in our best tuners and
receivers, takes part in FM detection and IF amplification. But the highlight
of the circuitry here is the new Quadrature discriminator transformer with
which the PA-3001A works. We call it a “one-pack phase shifter” because it
packs the conventional micro inductor an dthe discriminator with new bobbin
material in one shielded case.
Benefits
include the following:
Positive
protection against distortion.
Improvement
of input vs. distortion characteristics.
Reduction of nopise for a better S/N
Reduction of nopise for a better S/N
Increased
stability against temperature/humidity changes
Still Other
Pioneer ICs in FM Section
Audiophiles
know that Pioneer was among the first to perfect an MPX or stereo FM multiplex
demodulator that resists all externbal influences to provide clean, wide stereo
separation. This means the stereo images in the reproduced sound field never
waver or blur, never leave you in doubt if the station you are hearing is
stereo or mono. In specific terms, the stereo separation in the TX-7800 is a
full 50 dB at 1 khz. Frequency response is in no way compromised to achieve
wide separation, by the way. It remains 20 to 15,000 Hz +0,2 dB, -0,5 dB at all
times.
The
Pioneer-exclusive IC no. PA-1001A encapsulates our PLL MPX together with a
built-in Automatic Pilot Signal Canceller system to ensure that the stereo FM
switching signal does its intended job with no problems. Also included is a new
independent left/right-channel MPX Lowpass Filter; since the filter sections
are independent for each channel, mutual interference is remarkably reduced.
The Pioneer PA-1002A, still another exclusive IC, is found in the audio amp and
FM muting section. Higher accuracy and better musicality are again the
benefits.
IMPROVED AM
FIDELITY, TOO
A new AM
broadcastsing channel plan has been put into effect worlwide. It reduces the
conventional interval between AM stations from 10 kHz to 9 kHz, a fact we
expect to increase AM noise and interference still more. We took this into
consideration when we built the TX-7800 and included a selectable Wide/Narrow
IF bandwidth for the AM section.
A wide band
LC filter is put on line when you switch to Wide band AM. This reduces
distortion to suit the higher sensitivity of the tuner when receiving AM
signals of normal strength; this, in turn, means a wider effective frequency
range and cleaner reproduction. When the station you want is weak or distant,
switch to Narrow. Here a precision ceramic filter is added to the circuit to
cut out all sorts of interference. You can easily hear the differences .
A tip: the
movement of the signal meter is related to the characteristics of the
Wide/Narrow selectivity of AM. When you tune in strong-signal stations we
recommend that you use the Narrow mode for pinpoint selection, then switch to
Wide to enjoy better sound quality.
AM Circuitry
Aims at Hi-Fi Quality.
No one can
rigtly claim that AM is truly hi-fi in the conventional sense of the term. But
Pioneer engineers have tackled distortion, noise and frequency esponse factors
to make AM as “hi-fi like” as possible. An IC with superior characteristics in
lowering low-frequency distortion is used in the RF amp and AM detection stage.
After detection, the signal is sent to two Pioneer exclusive ICs for
amplification. With the Wide/Narrow
facility described above, this elaborate circuitry does make AM listening more
enjoyable by eliminating booms, whines and whistles for a cleaner sound.
Still More
Advantages.
Output Level
Control – Front panel control to adjust output level.
Twin Outputs
– Two sets of stereo output terminals are provided. One has a fixed output, use
it for connection with your amplifier. The other has variable output ( with
output control), use it for direct connection to tape deck, etc.
MPX Noise
Filter – Front panel switch to cancel stray noise from FM carrier when taping.
FM Muting
/Mode – In the Off position the Servo-LockFM Tuning system is out of ciruit.
LED
Indicators/Index Markers – Further aids to fast and accurate tuning. The lights
for Stereo and Locked (red and green) can never burn out. The index markers
slide to your favorite stations for convenient re-tuning.
FM
De-Emphasis – Rear panel switch for selectable de-emphasis.
FM Multipath
Outputs – Horizontal and vertical
Click Noise
Canceller – All function switches backed by clik-noise canceller circuit for
silent operation.
Versatile
Styling - Straightforward looks and
diamond cut dial scale finish increase appeal. Styling is coordinated with
other new products from Pioneer.
Specifications
FM Section
Usable
Sensitivity: 9,3 dBf (1,6 µV) [Mono]
50 dB Quieting
Sensitivity:
Mono : 15,5 dBf (3,3 µV) / Stereo : 37,1 dBf (39,2 µV)
Signal-to-Noise
Ratio (at 85 dBf):
Mono : 83 dB / Stereo : 79 dB
Distortion (at 85 dBf):
At
100 Hz : 0,08% (mono) / 0,1% (stereo)
At
1 kHz : 0,05% (mono) / 0,08% (stereo)
At 10 kHz : 0,06% (mono) / 0,3% (stereo)
Frequency
Response: 20 – 15,000 Hz +0,2 dB, -0,5 dB
Capture
ratio: 1,0 dB
Alternate
hannel Selectivity: 75 dB
Spurious
Response Ratio: 95 dB
Image
Response Ratio: 85 dB
IF
Response Ratio: 100 dB
AM
Suppression Ratio: 65
dB
Muting
Threshold: 19,2 dBf (5,0 µV)
Stereo
Separation: 50 dB (1 kHz) / 35 dB (20
– 10,000 Hz)
Subcarrier
Ratio: 70 dB
Multipath
Jacks: Vertical and Horizontal
De-Emphasis
Switch : 25 µS - 75 µS (switchable)
Antenna
Input: 300 Ω balanced, 75 Ω unbalanced
AM Section
Sensitivity:
300 µV/m (IHF, ferrite antenna) / 15 µV(IHF, external antenna)
Selectivity [Wide/Narrow]: 15 dB / 50 dB
Signal-to-Noise
Ratio: 50 dB
Image
Response Ratio: 45 dB
IF
Response Ratio: 50 dB
Antenna:
Buil-in ferrite loopstic antenna
Audio
Section
Output
Level/Impedance:
Fixed
: 650 mV (FM), 200 mV (AM) / 4,2 k Ω
Variable
: 0 mV to 1,3 V (FM), 0 mV to 400 mV
(AM) / 3,6 k Ω
FM (100%
Mod)
AM (30% Mod)
Semiconductors:
2 FET; 7 ICs; 11 Transistors; 30 Diodes
Power Requirement: 110 -240 V 50/60 Hz
Power
Consumption: 23 watts
Dimensions
(W x H x D): 420 x 150 x 390 mm (16-9/16” x 5-7/8” x 15-3/8”)
Weight:
7,5 kg (16 lb 9 oz) net
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