20-11-2015, 05:38 PM
I'm looking at the trader sheet for the HMV 1121, it shows the osc grid resistor as 47k, if you are reading 53k then it's not far out and may well be with the original manufactured tolerance , that difference of 6k wouldn't normally affect the performance of the radio to any great extent.
It would be a good idea to check the mixer anode voltage and the mixer screen voltage while you are working on that stage, if you study the schematic you will see that the screen voltage to the mixer is supplied via a potential divider, you will find that many radios use that same arrangement, either of the resistors that form the potential divider can be prone to changing value over the years, there's stuff in radio books etc that explain why the divider circuit is used.
Also check the osc anode voltage as a matter of course while probing around there, it's all good practice.
Lawrence.
It would be a good idea to check the mixer anode voltage and the mixer screen voltage while you are working on that stage, if you study the schematic you will see that the screen voltage to the mixer is supplied via a potential divider, you will find that many radios use that same arrangement, either of the resistors that form the potential divider can be prone to changing value over the years, there's stuff in radio books etc that explain why the divider circuit is used.
Also check the osc anode voltage as a matter of course while probing around there, it's all good practice.
Lawrence.
