06-05-2020, 08:45 AM
This one baffles me.
The set does demodulate the input signal and plays back a tone, but it's exactly twice the original frequency.
For example, if the original pre-modulated input is a sine wave at 600Hz, the result is also a sine wave but at 1200Hz.
Most passive components have been changed by now, and the result is the same even with other tubes. Right now I have C405 reading 75 pF instead of 56 pF as per the schematic. Should it be changed?
Also, the "canned" R and C components at the 2nd IF transformer have not yet been checked or replaced.
Any comments or remarks appreciated.
All the best.
JZ
The set does demodulate the input signal and plays back a tone, but it's exactly twice the original frequency.
For example, if the original pre-modulated input is a sine wave at 600Hz, the result is also a sine wave but at 1200Hz.
Most passive components have been changed by now, and the result is the same even with other tubes. Right now I have C405 reading 75 pF instead of 56 pF as per the schematic. Should it be changed?
Also, the "canned" R and C components at the 2nd IF transformer have not yet been checked or replaced.
Any comments or remarks appreciated.
All the best.
JZ
