578
Item nr.
FM Bug
| Production | China, 2023.
Price was 85ct (plus shipping). |
|---|---|
| Bands | FM (88-108MHz). |
| Semi- conductors | LED, 9014 (AF preamp), 9018 (Osc), 9018 (RF amp). |
| Cabinet | Size 54x41mm. |
| Power | DC 3-6V. |
| Documents | Schema. |
A small FM transmitter for home use. For just 85ct (plus twice that for shipping) the unit arrives as a kit. The unit has an on board condenser microphone, amplified by Q1 (9014). External audio can be offered through a jack, that mutes the mike. The signal then modulates the base of Q2, the FM oscillator. Carrier frequency is tuned by coil L4. Transistor Q3 amplifies the signal and then this is fed through a pi-filter to the antenna.
| Obtained | 4/2023 from AliExpress. |
|---|---|
| Condition | 8. |
| Value (est.) | 2,2€. |
This is how the parts arrived. I don't know how experienced I am, but it took me about one hour to assemble all components and then it worked immediately. 
With this little FM transmitter, I should be able to overhear my favorite AM Golden Oldies station in my garden on an FM set (including all the fading and static). So I wanted to build it into an AM portable set. I chose the Philips D2603, because it tunes AM, including Tropical Bands and Shortwave, and FM. The supply voltage (6V) is quite right for this bug. Also, for some reason unknown to me, the radio was already equipped with two HF antenna's, the whip and a wire in the back of the cabinet. I use the whip for reception and the wire for FM transmission. The photo to the right shows the bug built into the Philips, and you can compare that picture to the almost similar one showing the inside of the D2603.
