Grundig Satellit 700
Written by Bryce Ringwood   

The Grundig Satellit 700 receiver was made in Portugal from about 1992 until 1996. It covers Long Wave from 150-353kHz and Medium and Short Wave from 528 to 30000kHz. It also covers FM (Stereo) Satellit 700and uses the RDS system to track and identify FM stations. It was generally considered to be a very good receiver and one of its outstanding features was its good audio quality. It doesn't really qualify as an OLD radio though.

The set has a great number of features for the dedicated short-wave listener. These include variable selectivity, SSB and Synchronous AM reception, 512 Memory presets, digital tuning using a (phase-lock loop) frequency synthesizer, a large LCD display and built-in aerial for AM and FM reception.

All these features are masterminded by two computer chips (CPUs) and controlled from buttons on the front panel. Although it has a tuning knob, this is used to send pulses to one of the CPUs, leaving gaps of silence between each click of the knob. I have since received another set, (which I passed on to Grundig for repair.) The tuning knob arrangement is not satisfactory if you are sweeping across a band looking for a station. If you are planning on servicing your set yourself - please beware of the ribbon cables soldered directly to the circuit boards. They can easily break at the connection and they are a terrible job to restore. 

The set is constructed on four printed circuit boards. One for the audio, another for the radio frequency functions, another for the CPUsGrundig Satellit 700 RF Board and finally, a display board. The set is constructed using surface-mount technology, where possible, with support from some pin-in-hole components.

Somewhere in the set, there is a rechargeable lithium battery designed to keep certain functions, such as the timer, alive when the normal batteries are exhausted. I wasn't able to physically find it, or find it on the circuit diagram. I think its on the processor board.

The set presented to me would not receive FM. All that could be heard was loud hash – sometimes called “sharsh”. I warned the owner that because of the technology and date of the radio, I probably would not be able to fix it. In fact, the radio was fairly straightforward and the problem was traced to the FM mixer. This had decided to break into oscillation – rather in the manner of the regenerative receiver. The fact that I could hear the noise and that I could trace a signal at intermediate frequency led me astray for a day or two.

Having replaced all the mixer components (except for the faulty one!) with no luck, I checked the secondary of the first IF transformer. It was open-circuit. This would have reduced the load on the mixer transistor, making it misbehave. This transformer would have been specially made, so I had to replace it with a compromise – a “standard” 10.7MHz transformer. This immediately brought the FM band back to life, but the performance can't be expected to match the original and the stereo decoder was no longer able to resolve the pilot tone. This is sad, but better than no FM at all.

The problem with radios made from about the late 1970s onward is that manufacturers could source “tailor-made” integrated circuits and other parts in sufficient quantities for a production run, with very little left for spare parts. Even the standard parts are not in common use. For example, the set uses a “BF999” transistor in several parts of the circuit. These are current parts made by “ a firm called “Infineon”, but they seem to be sold in lots of 3000 to special order. The computer chips were made by “Microchip (I think) – but even if it were possible to purchase one, the firmware would have to be written to it.

I have since got a few BF999 transistors.

All these characteristics of modern radios lead some people to dismiss them as “rubbish” and use derogatory terms such as “sand-boxes” when referring to them. In fact, modern radios are very well designed and seldom give any trouble. Unfortunately, they are small and therefore can fall or be dropped. I suspect that this is what had happened to this Grundig, the shock of the fall may have severed the fine wires inside the transformer.

Grundig no longer make shortwave radios. The Grundigs are now marketed as Eton. You might want to compare this with the Eton G3 (Which is probably illegal here, since it covers the aircraft band.) 

Schematics for the Grundig are available for members of radiomuseum.org. 

 
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