364
Item nr.
Early FM portable
| Production | The Netherlands, 1960. |
|---|---|
| Bands | LW, MW, FM (87.5-100MHz). IF is 460kHz for AM and 6,75MHz for FM. |
| Semi- conductors | OC171 (RF), OC171 (mixer FM), OC170 (FM IF and AM mixer), OC170 (IF), OC75 (AF amp), OC75 (driver), 2x OC74 (output), OA90 (FM), 2x OA79 (FM det), OA79 (det). |
| Cabinet | Plastic. Size 27x18x10cm. Weight 2.1kg. |
| Power | Batt 9V, either 2x4,5 or 6xC. |
The radio came with a carrying bag (photo left by Dina).
| Obtained | Was never mine, Repaired for Tanneke, 9/2013. |
|---|---|
| Condition | 7. |
| Sound sample | PLAY SOUND I am more used to radio with hearts of glass (tubes), so this was a real pain in the ass. But I managed to repair the radio, and learned a lot in the process. |
The radio runs on 9V of battery power, and the battery holder is shaped in a special way (I had only seen this before in a Soviet portable Alpinist 405) to hold either flat torch batteries (very common in France) or C type batteries. The inside picture shows that almost all electrical parts are found on a single chassis, a PCB. 
These two pictures show the Printed Circuit Board, taken out of the radio, on the front and back sides. To take out the chassis, you must unscrew four bolts and unsolder a few wires (antennas and loud speaker).
The entire HF section of the radio appeared to be as dead as a doornail, and on the internet I found that the transistors OC171 and OC170 are notoriously unreliable. The construction allows the formation of hair structures inside, that cause internal shorts in the transistors. There are ways to extend the life of a transistor, but the only true remedy is replacement of the transistors. Here is a replacement table, but be aware that some of the "new" types may no longer be available by now! So I bought AF139's, which are a bit smaller (see photo left). Each transistor has to be soldered with four wires, which should not be permuted, so this was quite some precision work. But I managed to replace all (see photo right), after which I could enjoy some sounds from the radio.
A bad contact (switch U2) caused intermittent interruption of sound, which I remedied by soldering a 47k resistor from u2 to u2'.
