579
Item nr.
Successor to Sharpie
| Production | Belgium, 1958.
Price was fl 198. |
|---|---|
| Bands | LW (1132-2000m), MW (184-580m); IF is 452kHz. |
| Semi- conductors | 2N412 (mix), 2x 2N410 (IF), 2x OC71 (AF), OA79 (det.), 2x OC72 (output). |
| Cabinet | Plastic. Size 28x18x9cm. Weight 2.5kg. |
| Power | Batt 6xD. |
| Obtained | 4/2023 from Wim van Toor, sn=PL41480. |
|---|---|
| Condition | 7; MW ferrite coil was replaced, LW coil is broken, plays well on MW. |
| Disposed | Sold 2/2024. |
As for all defective radio's, I first did an oscillator test and found out that the local oscillator works fine. Then, a modulated signal on de base of transistor 1 produced sound in the speaker, so I suspected the antenna circuitry. 
There was a loose wire on coil S2 (Medium Wave coupling coil) on the ferrite rod, which interrupted the coil, and I could repair this. But still no sound. Further measurements revealed that S3 (Long Wave tuning coil) was also interrupted. This coil is parallel to the MW tuning coil in the MW position, so I expected some misalignment, but not complete silence. Through the transistorforum I learned that an Evette can play om MW without the LW coil, so I had to find another defective. More precise measuremens on coil S1 (MW tuning) revealed that its resistance was too low. Fortunately I had a very similar coil (see photo left), albeit without coupling coil. I formed a coupling coil with 4 turns of ordinary wire (photo right) and then the radio worked again.
Here is the diagram of the RF circuitry. Following the wires and switch positions, you can see that one of the coupling coils (S2 or S4) is selected. But when MW is selected, S1 and S3 are both in the circuit.
I had a dirty L3X80T before but that was in very bad shape. The Evette is more sensitive and gives better sound than the Sharpie. The Evette runs on 9V (Sharpie on 6V) and its output power is 350mW (Sharpie has 200mW).