Pioneer TX-7800

 Pioneer TX-7800 Stereo FM/AM Tuner with Servo-Lock / Touch-Sensor Tuning.
Significant Improvements in Accuracy Fidelity and Convenience
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).
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.
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
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.
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.
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 (169/16” x 5-7/8” x 15-3/8”)
Weight:  7,5 kg (16 lb  9 oz) net
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