More TEF6606 info

For the circuit that was constructed for testing (based on the Application circuit in the data sheet, the v3 copy of the datasheet is here), the TEF6606 was powered directly via a 9V alkaline PP3 battery (not ideal, because the ic consumes just over 100mA so the battery won’t last long). The 4MHz crystal was just whatever was available from Maplin. The microcontroller and I2C bus was at 5V (powered through MC78L05ACP TO-92-sized regulator).

The TEF6606 exhibits about 60mV amplitude (peak-peak) of RF (about 110MHz) at the audio outputs of the IC. I saw this in the ‘uninitialized’ state, I didn’t check once the IC has been programmed to tune a channel. This was observed on a scope, and I’ve not used a spectrum analyzer on it.

Regarding audible noise (BW limit the scope to not see the RF), I saw about 16mV p-p of noise on the audio outputs of the IC in the uninitialized state. Once tuned to a channel, the audio level of the music (in FM mode) is about 0.9v p-p. It proved capable of directly driving 2×32 ohm headphones, although it is not really designed for that.

With a lack of time and equipment to test it with, as a subjective opinion, the overall quality of the IC is not bad. It is far better than most FM receiver circuits, although it is certainly not in the same league as high-end home tuners. Anyway, it is intended for car hi-fi applications and there it would be great.

Info on the coils:

L1 (290nH):

Use any wire (bare, enamelled, etc – I used enamelled) up to 22SWG thickness (I used 24AWG), and wrap around 5mm drill bit, 12 turns exactly. Then, stretch to 1cm length, and use a little bit of epoxy glue to hold the shape.

L2 (215nH):

Use any wire up to 22SWG thickness (I used 24AWG again), and wrap around 5mm drill bit, 10 turns exactly. Then, stretch to 0.9cm length, and use the epoxy again.

3.3uH power-supply choke on pinĀ  22:

Any off-the-shelf device should be fine. Difficult to tell how effective it was running in the test circuit, but I just used an Amidon FT-23-61 toroid with 12 turns of tefzel (or it may have been kynar) wire which is usually about 30SWG.

Photo of L2 (left) and L1 (right):

radiocoils.jpg

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