Below is what I have tested after checked the alignment:

• T1 opened again and tested all coils. All coils test per schematic. Wired in correctly.
• Tested secondary band switch (7, 8, 9, 10, & 11), looks to be working correctly no shorts detected to ground or other pins on switch.
• Tested T4 on IF side. No shorts detected and all coils test to schematic.
• Lifted R9 from ground with C5 connected to T1 correctly and not connected to T1, AVC voltage would increase by 2 to 5 vdc whether C5 was correct or not.
• Lifted R14 from R12, AVC voltage was cut in half whether C5 is wired correctly or not. Note my radio does not have C34, R13, and C35 since my R12 was replaced sometime in the past.
• When I lifted R14 I noted the voltage at R10 and R12 would slowly climb to -66vdc. When I connected R14 back, the voltage would drop back to about -40vdc.
• I lifted R15 from the plate of the 6H6. No AVC changes whether C5 wired correctly or not.

Ok not sure if this tells us anything.

Hey, I just noticed something.
The removal of C34/R13/C35 not only took out the tone compensation from the volume control, but it also removed half of the I.F. filter.

Once the I.F. signal is detected ("rectified") the 455kHz component has to be filtered out to leave only the audio portion to go into the volume control. The 50 mmf cap C32 is the first part of that filter. On cheap sets, there's often just the one cap to ground there, but it is usually larger in value.

But better is a "pi filter" consisting of two caps to ground, separated by a resistor.
I've seen this refered to as a "tweet filter."
I have the little brother (62-417) to your set and it uses this arrangement, as shown here:

Your set has the 2nd filter cap C34 100 mmfd connected differently but still doing the same essential job.
Lack of that capacitor probably means inadequate I.F. filtering.
It's hard to say just what the consequences should be, and whether that will be affecting your AVC voltage, but it may be worth your while to add the 2nd 50 mmfd cap to ground as shown above, until you are able to obtain the correct volume control.
------------------------------
That lifting R15 from the 6H6 has no effect is not surprising. That second diode in the 6H6 is used as a "clamping diode" and is there only to ensure that the AVC line does not go positive due to some aberent condition. In normal operation it is doing nothing. Simpler sets don't bother with it, but I guess they have a spare diode here, so why not use it?

Terry, I tried adding the 50mmf filter as you suggested. It had no effect on the AVC voltage at R9. I decided to check on some other caps to see if any had an effect on the AVC voltage. I removed each one, one at a time from ground and check the voltage, none of them had any effect. I tested the following caps, C46, C27, C10 and C20. Can someone tell me the purpose of C27, it is a filter cap and I noticed no difference in the voltage or sound when it was removed.

I am wondering if the schematic is wrong. I doubt it, but as long as I have C5 disconnected from T1 and ground the connection on T1 the tuning eye works great and the radio works as expected all up and down the dial on all bands.

Thanks

I think the schematic is actually right, but the C5 capacitor you have is for some reason not providing the RF ground that would be expected.

Technically C5 is part of what is called the antenna tank circuit. However, if for some reason C5 as a .05 cap isn't very good at providing a low loss RF path, the operation of that tank circuit could be very poor. Directly grounding T1 removes C5 as part of the tank circuit. However it also removes the AVC from the first tube.

So what if we could leave the direct ground, but get back the AVC connection. Well, that is possible with the circuit below. The nice thing about this is that the 0.01 cap doesn't have to be a great RF cap because it is no longer part of the tank circuit. It is just coupling RF to the high impedance tube input.

The 100K resistor takes care of reconnecting the AVC.

No values are critical. The 0.01 cap could be probably anthing from 470 pF to 0.1. The 100K resistor could probably be anything from 10K to 470K.

Now once you connect this I expect the peak AVC voltage to go down. Why? Because you are (hopefully) getting back a control stage so that the IF stage is not having to do all of the gain reduction which required the AVC to go clear to -33 volts to achieve this.

Typical AVC will often peak at about -20 on a real strong local station.Curtis Eickerman

Curtis tried your idea, this is what I found:

AVC voltage with the Grid of 6G5 jumped over R8: -15.9vdc
AVC voltage with the Grid of 6G5 jumped over R8 with the .01 and 100K installed: -9.0vdc
For both tests I had, the T1 shorted to ground and C5 connected to #7. I had peaked the alignment again. The radio is tuned to 1400kc, connected to my external antenna. My shop transmitter is tuned to 1400kc.

Just so I understand, with T1 grounded and C5 connected to #7 only, the AVC is not working (high neg) and that is why any stations I tune in are louder then if I have T1 wired up correctly (low neg dc).

I believe you are understanting this correctly.

It's kind of like having two volume controls on a radio and neither can turn the volume all the way to zero. If only one control can be turned down then the radio will be louder no matter what you do because that control just won't go any lower. The high AVC voltage is just indicating how hard the AVC is trying to turn down that poor control that just won't go any lower.

When both controls are operating it doesn't take as much "force" from the AVC to get the job done.

The best proof that things are operating correctly is the ability to tune from station to station without having much need to adjust the volume control to keep the audio at a comfortable volume. You should also hear noise between stations as the gain rises in the absence of a signal.

I would generally expect the AVC to get to somewhere in the -10 V to -15 V range on a really strong signal. So, -9 V is not terribly out of line. When you were only getting something like -4 V that just doesn't seem right.

Curtis Eickerman

Ok, so I am clear when you say -10 to -9vdc for AVC. You are referring to a voltage reading at #1? To get any movement on the tuning indicator that is where I have the grid of 6G5 connected. If I connect the 6G5 per the schematic, wire in the additional cap and resister, to the cap of the RF as above. The voltage peaks at around -3vdc using a signal generator. Since my AVC is low no matter what we have tried to date, should I just remove R8 and R9 and connect to #1, or look to replace the 6G5 to a 6E5?

Yes, I was referring to the voltage at #1. Also, I looked up the 6G5 data and can't see why they used R8 and R9 to cause a 2:1 voltage divider. That tube was rated for the eye close with about -18 V on the grid with 200 V on the plate. So, I could see no reason why you couldn't just disconnect R9. You could leave R8 because there will no longer be any significant voltage loss without R9.

The R8/R9 divider would just desensitize the closing of the eye tube if it tended to close too easily.

It actually looks like they designed for a 6E5 then plugged the 6G5 in at the last minute. The 6E5 closes at -8 volts.

Alternatively, maybe they intended to do this which would have given you a very lively indicator. This would have divided in half the AVC to the RF and IF while connecting the full voltage to the 6G5. Hard telling. You could even drive just the RF or just the IF from the reduced line to get performance somewhere in between. Curtis Eickerman

OK, here is something I noticed last night. I have done all testing with the radio plugged in to a variac and isolation transformer. Last night I plugged it in to an outlet on the bench and quickly discovered I have a hot chassis. I have 119vac from chassis to earth ground. I flipped the plug and of course, I have 119vac to ground with the power switch opposite. This is just like a hot chassis. I am looking over the wiring for the filaments and rectifier, but I have not touched or replaced any of the wiring in that part just the caps and resistors. I noted there are not any line-to-ground caps, I did place some in line with no effect. Any idea were I have this stray voltage?

Skip

Agree with Curtis. No way will your AVC generate enough negative voltage to close the eye using a 6U5/6G5. It takes minus 40 volts with the divider. Removing R9 may be enough to give satisfactory operation?

Even without a cap from the AC line to chassis there will be some leakage. Using a meter on a high resistance range measure between chassis and line cord, with power disconnected. If any reading should be many megs. Low resistance could indicate leakage in power transformer or motor.

I wanted to wrap this up and thank everyone who stuck with me and helped educate me on AVC.

I did g with Curtis and Norm’s suggestion to us a 6E5 tube and modify the circuit slightly. It works very well so I am happy with it.

As for the AC on the chassis like an AC/DC radio, yes it was bleeding through the mounting bolts on the electric tuning motor. I just replaced the mounting bolts with nylon bolts and the eliminated the problem.

I have also completely refinished the cabinet. The trim is toned darker then original, but I think it looks good. Again thanks.

Skip

Looks great...