04-13-2013, 10:08 AM
Well.... color me stoopid....
I've solved the entire problem with the output on this radio. It sounds quite nice now, as long as I keep the volume level below the level the signal itself distorts going through the RF/IF chain. I get at least a good 2 volt signal across the voice coil before clipping. I'm not familiar with the voice coil impedence on this speaker, so can't compute the RMS power, but it's quite loud.
Now, wouldn't you like to know what the problem was? Wouldn't ya?
Well, let me tell you.. some idiot who shall remain ME connected the interstage transformer to the plates and the output transformer to the grids of the 45's. It's a wonder that a) any audio made it through to the speaker at all and b) the grids didn't melt down with B+ on them. I might have caught my error sooner if the grids had ANY DC bias on them at all (or maybe I should have taken better notes when I disconnected all the leads from the bottom plate..)
I'm sure that the 45's are probably pretty damaged at this point, so it's a good thing I have some more coming in. At least the radio is working and I can honestly say that I've tackled one of the biggest PITA radios in existance, and come out the winner.
What makes it even more amazing is that when I got the radio, it was in the form of a 3-D jigsaw puzzle. The cabinet was totally disassembled, the speaker lying on top of the chassis, the knobs broken off (not the shafts), the tuning mechanism broken, the power transformer extra crispy and literally everything in the filter can needed to be replaced (except the RF choke, but rather than re-use that and have it go out later, I just bought a new 50uH RF choke and replaced everything in the can.
I wish to thank everyone here that helped me with this set. All help is greatly appreciated.
Take care, and stay well.
I've solved the entire problem with the output on this radio. It sounds quite nice now, as long as I keep the volume level below the level the signal itself distorts going through the RF/IF chain. I get at least a good 2 volt signal across the voice coil before clipping. I'm not familiar with the voice coil impedence on this speaker, so can't compute the RMS power, but it's quite loud.
Now, wouldn't you like to know what the problem was? Wouldn't ya?
Well, let me tell you.. some idiot who shall remain ME connected the interstage transformer to the plates and the output transformer to the grids of the 45's. It's a wonder that a) any audio made it through to the speaker at all and b) the grids didn't melt down with B+ on them. I might have caught my error sooner if the grids had ANY DC bias on them at all (or maybe I should have taken better notes when I disconnected all the leads from the bottom plate..)
I'm sure that the 45's are probably pretty damaged at this point, so it's a good thing I have some more coming in. At least the radio is working and I can honestly say that I've tackled one of the biggest PITA radios in existance, and come out the winner.
What makes it even more amazing is that when I got the radio, it was in the form of a 3-D jigsaw puzzle. The cabinet was totally disassembled, the speaker lying on top of the chassis, the knobs broken off (not the shafts), the tuning mechanism broken, the power transformer extra crispy and literally everything in the filter can needed to be replaced (except the RF choke, but rather than re-use that and have it go out later, I just bought a new 50uH RF choke and replaced everything in the can.
I wish to thank everyone here that helped me with this set. All help is greatly appreciated.
Take care, and stay well.
