11-27-2017, 11:24 AM
Two capacitors I have not changed:
1) there is a .006 between the cathodes of the 7AF7 RF tube that is in an almost impossible location to change. Since the voltages there are very low and the impedance is also low there, I elected not to change it.
2) there is a .003uF@600VDC capacitor across the primary of the audio output transformer. I have not changed it, but do plan to do so. Usually you see capacitors in this application that are rated at 1KVDC or higher. It is there to suppress high AC spikes from noise impulses that make it through to the audio detector and amplifier stages. It is supposed to protect the output tubes plate circuits and the output transformer primary from transient spikes beyond their expected operating ranges. I will have to order this one as I only have a .001 rated at 1KV.
For now I have not changed any of the mica capacitors in the set as they usually are good. If any do prove to be bad I will do so.
Joe
1) there is a .006 between the cathodes of the 7AF7 RF tube that is in an almost impossible location to change. Since the voltages there are very low and the impedance is also low there, I elected not to change it.
2) there is a .003uF@600VDC capacitor across the primary of the audio output transformer. I have not changed it, but do plan to do so. Usually you see capacitors in this application that are rated at 1KVDC or higher. It is there to suppress high AC spikes from noise impulses that make it through to the audio detector and amplifier stages. It is supposed to protect the output tubes plate circuits and the output transformer primary from transient spikes beyond their expected operating ranges. I will have to order this one as I only have a .001 rated at 1KV.
For now I have not changed any of the mica capacitors in the set as they usually are good. If any do prove to be bad I will do so.
Joe
