Grundig Satellit 210/Transistor 6001
Contact: 
I received my Satellit as a gift in 1970 and I used it mainly for SW listening until when I purchased the SONY ICF-5900W and then the FRG-7. Then I used it mainly for FM given its excellent audio quality. In recent years it began to develop faults, due to age, both in the electronics and in the quite complex mechanics. A brief summary of the restoration work is described below.
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| Dimensions and weight: 26 cm high, 44 cm wide, 13 cm deep. Weight: 5.6 kg Power requirements: 9 VDC (6 internal D cells) or internal AC adapter TN14 |
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To separate the chassis from the cabinet just remove all the knobs, then unsolder and remove the telescopic antenna, unsolder the three wires going to the loudspeaker and the three wires connecting the battery holder to the radio. Finally remove two large black screws on the top deck and two small screws inside fastening the chassis to the wooden cabinet and you are done. The internals look like this. I wired temporarily a small loudspeaker to use it in the debugging phase (use the wires of the main speaker, not of the tweeter, otherwise the audio won't work on AM). The vertical circuit board on the left accomodates the IF and audio amplifiers. The board on the top left is for the volume and tone controls. All the rest is taken by the circuitry and mechanics of the various RF sections. | |
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A few years ago the transmission belt which links mechanically the SW drum tuner and the SW drum dial failed. It is a toothed belt made of plastic which had become brittle and broke up. The radio worked and changed bands correctly but there was little use since the dial could not change synchronously. With little hope of finding a replacement after 40 years I stored the radio away. Recently I found the belt offered on Ebay so I could replace it. | |
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When I switched the set on I found that it was completely dead on the SW bands. So I started investigating. The first thing I did was to check for the signal from the 2nd local oscillator (T6) on 2310 kHz. Listening with a small radio tuned to 2310 kHz close to the Satellit showed that the LO was dead. The culprit was the would-be diode 90002 which gave a drop of 0.9 V instead of 1.25. I say "would-be diode" because 90002 is really a kind of varistor. It seems that in the seventies it was popular to use varistors to stabilize voltages (SONY HI-FI audio amps also used them) but they are prone to failure. What I learned is to take seriously even a voltage difference of 0.3 V before drawing conclusions and dismantling parts (see below.) | |
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Inside view of the chassis seen from front. The dial plate has been removed to gain access to the SW drum tuner. The white barrel (plastic, not ceramic!) holds all the coils and capacitors for the RF, mixer and 1st local oscillator (LO) of the SW2-9 bands. The concept was the same as for the television VHF turret tuners and was instrumental in reducing stray capacitances and inductances, allowing very short connections. A second octagonal rotatable barrel, holding the dials for the SW bands 2-9 is also visible. It is mechanically linked to the white barrel so they move together when changing band. On its left the small rectangular metal can encloses the variable inductors for the permeability tuning of the MW band. Lots of interconnecting cables, strings and pulleys for the various dials, and trimmers can be seen. Access is a nightmare, requiring major dismantling operations, with the risk of breaking components. | |
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Detail of the SW tuner. The RF, mixer and oscillator transistors are mounted on the bakelite strip PCB. The spring contacts connect the PCB with the RF and mixer transistors to the the coils and capacitors mounted inside the rotatable barrel. Diode 90002 is placed on this PCB. I snipped off the diode and replaced it with two 1N4148s connected in series. | |
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Detail of the 2nd mixer (T5) and LO (T6) board for the SW2-9 bands. The shielding can has been removed. The LO works on 1850 + 460 = 2310 kHz. The frequency is adjusted by the core in the lowest can. Transistors T5 and T6 are visible. This circuit uses two voltages: -7.75 and -6.50 V with respect to ground. 7.75 goes on the red wire, 6.50 is on the black one. The correct value of the difference (1.25 V) is crucial for its correct operation, and is supplied by the 90002 diode discussed above. Before understanding that the diode was the culprit I had removed this board, convinced that T6 was blown. The transistor was OK and so I finally pinpointed the bad diode. But putting this board back in place was a major headache. To check that the board was working I listened to the 2310 kHz signal on another radio. |
