[ChristianFletcher]

I have another of my lock down buys on the bench today which is a Lafayette 600A. It picks a few broadcast stations quite loudly but not as loud as I would expect. Running it from a 50 ohm signal generator its take 600uV before I hear a low audio tone at 80% modulation.

I dont understand the imput path from the antemma upto the mechanical filter MF1 and hoping someone will help walk me though the circuit.

I can see the front end tuning via SW1 but was expect the signal to enter via an RF ampifier however it the manual describes FET1 as a mixer stage. There is also a dotted line shown from SW1 to near RV2 I think this is the AGC line.

What is the purpose of SW4 ?

I would normally suspect a bad tranistor in the front end possible FET1 or TR-1 or a problem with the mechanical filter. I am not sure how to fult find a mechnaical filter?

I think I need to understand the signal path first before I start faulting. So hopefully someone will be able help with the circuit operation .

Thanks Regards Chris