[brandonkr1]

Okay so the radio is finally working!!!! It sounds really good! Only issue is I can only get one station that stretches across the band…. Anyone have any ideas??

[brandonkr1]

I tried adjusting the alignment screws in the back, but it doesn’t help. The one station I get is a very strong station here in town, and it seems to be over powering all of the other stations….

[BrendaAnnD]

What is the frequency of the station you are receiving? It sounds like you may have the IF's tuned to that rather than where they belong.

[brandonkr1]

The station is 580 it comes in all across the band 

And the previous guy that attempted to repair it had the alignment screws all the way in. So I’ll have to do this by ear.

[brandonkr1]

Also resistor 24 is getting very hot. I checked for shorts or bad joints, but everything is fine…

[Mondial]

I think Brenda is correct. It appears that you have the IF tuned to 580 kHz, which is why you hear the station regardless of where the dial is tuned. The IF trimmers (compensators) have a lot of range so it is possible that they could be tuned to 580 if they are loosened considerably.

I have a feeling your oscillator is still not working, otherwise you would be hearing all sorts of squeals as you tuned across the dial while listening to the 580 station.

Resistor 24 will get hot as it is a dropping resistor for the screen grid supply of the 6A7 and 78 tubes. You should read around 250V on one end and about 100V to 120V on the other when measured to chassis ground. If you see these voltages then it is normal and not overheating.

[brandonkr1]

Mondial 

Thank you I’ll check the voltages on the 24 resistor. I know one end is around 250, but not sure about the other end. 

It’s weird I switched the leads on the oscillator coil out of curiosity and it works exactly the same. So the oscillator is in fact not working. I measured the voltages on the 6A7, and CG to K should measure .18 according to schematic, but I’m getting around 147! I guess I could try re winding the coil in the opposite direction and see what happens. I know for sure it’s going the right way and has 17 turns. I checked it a million times and it is exactly how the original one was.

[Mondial]

Brandon, are you sure you have the socket terminals of the 6A7 wired correctly? Pin 4 is the anode grid (G2). It should connect to one end of your new osc coil winding and nothing else. Pin 5 is the control grid (G1). It should connect to the original long osc coil winding and the tuning capacitor.

Make sure you have the 147V reading on pin 4 and not pin 5 of the 6A7.

[BrendaAnnD]

What are you calling the control grid on the tube? A 6A7 behaves like two tubes in one, with a common cathode. The control grid is the tube cap (G4 on the schematic.)

As far as the oscillator, have you checked the larger section of the coil? It could well have a turn or two that is corroded and shorting together or opening the circuit. G1 is your oscillator grid, while G2 acts as its plate with the coil forming a Hartley oscillator. G2 will have a higher DC voltage measured against the cathode. The only way that the control grid should have anything higher than about -6 VDC on it is if there is a shorted cap on the AVC line. Make sure that your oscillator coil doesn't have any resistive path across any two pins where there shouldn't be one.

[brandonkr1]

The schematic says control grid which is G4. PIN number 4 on the tube. Should be .18 volts. I have removed the coil and tried winding it backwards and forwards. No difference whatsoever. These radios from the 1930s are an absolute nightmare to work on. AA5 radios form the 40s and 50s can have all weak tubes, rotten wire, and shorted capacitors and they will still work lol this radio is going back in the attic where it belongs. I appreciate everyone’s help, but this radio is not going to work again. I might just sell it as a parts radio, even though it is in excellent condition…

[BrendaAnnD]

Pin 4 on the tube is not G4. G4 (control grid) is the cap on top of the tube.

   

[gregb]

Brandon, where are you located? Maybe a more experienced Phorum member is close by and could have a look for you.

Greg B

[klondike98]

Brandon has deleted his account so he won’t be replying.

[radiorich]

Hello Bob,
Weird !!
Sincerely Richard

[Ron Ramirez]

And with the OP having left the Phorum, I shall pull the curtain on this thread.

   

A-Ba-De-A-Ba-De-That's All Folks!