Re: Wonderbar radio operation

Posted by humanpotatohybrid On 2023/12/14 20:40:48

HH56 wrote:
I believe it is a combination. The radio needs a broadcast signal, strength of what the radio responds to being modified by the sensitivity selection lever. That part of the circuit is what the large seeking bar on top responds to.

Noticed this in the schematic. The top-middle wire in this crop is the cathode connection from the RF amp tube which normally grounds out which is required for the RF amp to function. When one of the buttons is pushed, this ground connection is broken which halts the output of the radio by stopping the RF tube from working, meaning no signal will get to the rest of the amplification circuitry. Only when it the arm passes over the correct contact is this connection restored to allow the rest of the circuitry to react to the strong radio signal. Hence if the preset does not correspond to a station which the Wonderbar would stop at at the most sensitive setting, then the preset button will not stop there. All of this is noticeable in the audio output (mostly the lack thereof) during this process.

Original Image

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