Tecsun PL-600 TA2057 AM FM Receiver Chip Circuitry Question

[radiotek]

Tecsun PL-600 TA2057 AM FM Receiver Chip Circuitry Question

It looks to me like there are two possible signals that come off of pin 18 of the TA2057 AM FM receiver chip. If pin 18 is held low it enables the AM IF out and if pin 18 is high it enable AM detector out signal which I can comprehend but what is confusing is all of the additional circuitry doing including the two MOSFETS IQ13 and IQ14.

It would be appreciated if any engineers out there could explain the function of all this additional circuitry after pin 18.

 

[davenn]

It would be appreciated if any engineers out there could explain the function of all this additional circuitry after pin 18.

your response in that other forum......

Not sure what you are talking about. I have the original Chinese schematic for my Tecsun PL-600 and the TA2057 with pin 18 is on the schematic.

Maybe you are confusing the PL-600 with the PL-660.

Please examine the original Chinese schematic I uploaded.

you obviously misunderstood the reply by user - Usually Lurking

that circuitry is actually hanging off pin 17, not 18 and is to do with the stereo detection


Dave

 

[radiotek]

If you follow the path from pin 18 you will see that it leads to 1Q14 the first MOSFET.

Maybe I was unclear with my question. I basically wanted to know what the purpose of the MOSFETS were ?

 

[73's de Edd]

SIR radiotek . . . . .

Can you give me access to the whole schematic or model # and brand.
Initially and as a preliminary thought, I am certainly seeing that external slave circuitry as being related to being used to switch in the beat oscillator . . . with it using a transistor and a 458 khz xtal oscillator xtal .
This then lets your mosfets (used as solid state switches) switch up and inject the the BFO osc RF via the C2 coupling capacitor to be able receive SSB reception in the receivers AM mode.

All hams ALMOST EXCLUSIVELY use SSB in these times

73's de Edd

 

[radiotek]

Hi Edd,

The name and model of the radio is a Tecsun PL-600. The link to the schematic is: https://elektrotanya.com/tecsun_pl-600.pdf/download.html

Frank

 

[muha]

All radio waves work normally: FM, SW, LW, and SSB, but I have a problem with the MW wave, as it works with great noise and distortion as if it were a crackling sound, and no channel could be received on this wave. Is there an engineer who is able to advise me or a way to repair Holidays if this is common

 

[Externet]

...it works with great noise and distortion as if it were a crackling sound, and no channel could be received on this wave...

If all attempts fail; take the receiver to another neighborhood and power with batteries to rule out interference at your location.

 

[muha]

I tried in various ways and changed my place and went to the beach and tried again, but nothing changed and the sound continued and without the slightest sound for any radio station. Where do these sounds come from, are these sounds from the capacitors or from a damaged IC, or if an inappropriate power source is connected, it will affect negatively on the performance of the MW waves

 

[dkleber45]

If you follow the path from pin 18 you will see that it leads to 1Q14 the first MOSFET.

Maybe I was unclear with my question. I basically wanted to know what the purpose of the MOSFETS were ?


View attachment 36327

Hi there,
You made error it is not pin 18 controlling AM or FM all controlled by pin 16 and via transistor TQ10 when collector low it is AM and when high it is FM selected.