12-23-2013, 02:45 PM
Today I finished rewiring the chassis including most of the capacitors and a large number of the resistors. I am going to have to order a few more capacitors to finish up. I under-counted the .01mFd capacitors. I checked the B+ circuits with the field core speaker connected and found no shorts to chassis. I added a polarized AC power cord and turned the set on. All lamps lit and the tube filaments came on then I heard some slight hum and crackling from the speaker. The hum is not audible at any reasonable distance from the speaker. The volume control cause a considerable amount of static as it is adjusted as does the tone control. There is some audio oscillation as the volume is brought up.
I hear some clicks as I tune across the AM band at consistent spots. I believe the front end is working, but the IF is out of alignment due to having the IF transformers out and changing wires. The 1st. IF transformer slugs had to be turned nearly all the way in to get the assembly in and out of the IF can shield. I have my RF signal generator warming up and passing the signal by the frequency counter to be sure of the output frequency. The RF signal generator has a switchable internal audio signal generator. I will begin by injecting an IF signal and peaking the IF transformer coils until I can get a signal all the way through to the detector circuit.
I plan to do several things before I do more work on the set. First I have to put together some sort of wooden base to hold the chassis upright and secure it for access to both sides for troubleshooting and alignment. The radio chassis is heaviest on the end where the power transformer is located and at the front where the controls and push-buttons are located. It is heavy enough that I don't want to run the risk of having it turn over while I am working on it. It is sort of a basket case with the antenna, speaker and mounting board attached and trying to do much of anything without the risk of something falling over. I don't want to break any tubes.
Many thanks to everyone for their help along the way so far!
Joe
I hear some clicks as I tune across the AM band at consistent spots. I believe the front end is working, but the IF is out of alignment due to having the IF transformers out and changing wires. The 1st. IF transformer slugs had to be turned nearly all the way in to get the assembly in and out of the IF can shield. I have my RF signal generator warming up and passing the signal by the frequency counter to be sure of the output frequency. The RF signal generator has a switchable internal audio signal generator. I will begin by injecting an IF signal and peaking the IF transformer coils until I can get a signal all the way through to the detector circuit.
I plan to do several things before I do more work on the set. First I have to put together some sort of wooden base to hold the chassis upright and secure it for access to both sides for troubleshooting and alignment. The radio chassis is heaviest on the end where the power transformer is located and at the front where the controls and push-buttons are located. It is heavy enough that I don't want to run the risk of having it turn over while I am working on it. It is sort of a basket case with the antenna, speaker and mounting board attached and trying to do much of anything without the risk of something falling over. I don't want to break any tubes.
Many thanks to everyone for their help along the way so far!
Joe
