Re: Philips 2514
I think the LND150 got a bit stuffed while putting it on the little PCB. Trying to mess with it as little as possible. Removed the 10uF cap and put a 47nF in it's place so I have 50nF across the 10K Source resistor. Seems to be back where it was albeit the PCB is a bit messy. Ids is about 0.6 mA so there should not be a problem with core saturation of the interstage transformer. Definitely a bit of HF instability, will try some ferrite beads in a few strategic places in the next day or 2. Wondering about the hum, the O/P bottle has a centre tapped directly heated cathode. I have tried an old 2K Horn, sound wasn't very loud and hum was noticeable. Maybe the valve is a bit tired. The only mod to the radio so far has been to add a 39K resistor going to the reaction tuning coils with a 2uF cap for decoupling. This limits the possible current to the (B442) Mosfet to about 3mA at 150V well within the max dissipation limit. After the ferrites, next step is to attach the phones to the O/P of the interstage transformer without the valve and have a listen, If it is good then a FETand BJT combo will go on the base which I made up already.
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