Repair of a late-'40's Precision E-200-C RF signal generator - part one скачать в хорошем качестве

Repair of a late-'40's Precision E-200-C RF signal generator - part one

Here's a Precision model E200C service grade RF signal generator from circa 1949. When received; the old paper and electrolytic capacitors were leaky and some resistors were out of tolerance. After these parts were replaced, the generator had good RF output; but, the internal audio oscillator (modulation signal) was nearly dead and I could find no reason for this section not to work. There was one carbon composition resistor that was connected between the grid of the audio oscillator tube and ground that had gone up in value; so, I replaced it with two film resistors wired in series to get the correct value. I went back to a carbon composition resistor in this application and the oscillator worked much better; but, is still not as robust as it could be. For some reason, this circuit does not like film resistors and I will sleep on this overnight to see what I can do to improve performance.