So I been working on this old model 37, what a mess, but Iv got it going, something interesting happend last night Iv been try to find where a buzz noise is coming from and was playing around with grounding. The power in wire Im using is a three wire(Its what I had) Only was using two wires and for some reason I thought Id hook up the third wire to a ground to see what happens and the reception be came much better. Unplug it would loose the station plug in and it would come back? I thought Id share this, Not sure if that is a problem maybe that is a leak? anyway the buzz is still there Ill keep trying to fix that. Need to try a tube.

These old TRF sets not only needed a good antenna, they needed a signal ground connection, too, for best reception. Sounds like you created a signal ground from the radio chassis to your house wiring ground bus by connecting the cordset's ground wire to the chassis.

:These old TRF sets not only needed a good antenna, they needed a signal ground connection, too, for best reception. Sounds like you created a signal ground from the radio chassis to your house wiring ground bus by connecting the cordset's ground wire to the chassis.
:
:
:Dont know but seems to work, I made the antenna by going through the house copper pipe heating system that seems to work as well, picks up a bunch of stations and I live in northern Vt out in the woods. would have thought it would have grounded through that? Thanks for the reply. Having fun with these old radios.

On a TRF, one end of the antenna coil goes to the antenna, and the other is connected to ground, which completes the RF circuit. Connecting earth ground to either end but leaving the other end disconnected, usually won't give the best reception than if they are both connected correctly.

Study this AK-37 schematic: http://www.atwaterkent.info/TechData/Drawings/Images/AK09500sch.pdf

An AC-powered set like yours may become somewhat self-grounded by virtue of the stray capacitance between the transformer and the metal chassis/cabinet. Ideally, you should connect the water pipe to chassis ground and the antenna wire to the antenna terminal.

Your "buzz" may be due to leaky filter caps in the power supply. Often, the filter caps are OK, but they are paper, and subject to failure. You can disconnect the existing caps and haywire replacements inside the power pack can - without removing the tar.

:On a TRF, one end of the antenna coil goes to the antenna, and the other is connected to ground, which completes the RF circuit. Connecting earth ground to either end but leaving the other end disconnected, usually won't give the best reception than if they are both connected correctly.
:
:Study this AK-37 schematic: http://www.atwaterkent.info/TechData/Drawings/Images/AK09500sch.pdf
:
:An AC-powered set like yours may become somewhat self-grounded by virtue of the stray capacitance between the transformer and the metal chassis/cabinet. Ideally, you should connect the water pipe to chassis ground and the antenna wire to the antenna terminal.
:
:Your "buzz" may be due to leaky filter caps in the power supply. Often, the filter caps are OK, but they are paper, and subject to failure. You can disconnect the existing caps and haywire replacements inside the power pack can - without removing the tar.
:
Hi Ray, I restored an AK 37 Moderne for the TV show "American Restoration" on the History Channel. The chassis was a total mess. I think every Rat and their kin folk lived in that chassis for the last 50/60 years. All of the wireing and coils were eaten. With Warrans help I removed the tar and install a primetive PC board in it with all of the new caps. That was pretty easy to do. You would be surprised what they have stuff into those tar packs. Doug is right about not removing the tar it by far would be much easier to leave the tar in place. The only advantage to making a board with the caps on it is future troubleshooting of the power supply if needed. On your ground problem if you have a safe or metal window fram connect the ground to it and your resception will be much better, we connected the ground to an old gas pump door. It worked great. A wire antenna around 10/15 feet long should work fine. The buzz can easily be caused by what CV and Doug said so find a good ground even the frame if metal on your drop sealing if you have one will work. If you want to know how to go about rebuilding your power supply I can help you out big time on that. Kept all of my notes. LOL The radio we did for the show turned out beyond our wildest dreams, it was stunning. I'll try to keep an eye out for the thread and help you with any questions you might have. Best 2 U, George T

::On a TRF, one end of the antenna coil goes to the antenna, and the other is connected to ground, which completes the RF circuit. Connecting earth ground to either end but leaving the other end disconnected, usually won't give the best reception than if they are both connected correctly.
::
::Study this AK-37 schematic: http://www.atwaterkent.info/TechData/Drawings/Images/AK09500sch.pdf
::
::An AC-powered set like yours may become somewhat self-grounded by virtue of the stray capacitance between the transformer and the metal chassis/cabinet. Ideally, you should connect the water pipe to chassis ground and the antenna wire to the antenna terminal.
::
::Your "buzz" may be due to leaky filter caps in the power supply. Often, the filter caps are OK, but they are paper, and subject to failure. You can disconnect the existing caps and haywire replacements inside the power pack can - without removing the tar.
::
:Hi Ray, I restored an AK 37 Moderne for the TV show "American Restoration" on the History Channel. The chassis was a total mess. I think every Rat and their kin folk lived in that chassis for the last 50/60 years. All of the wireing and coils were eaten. With Warrans help I removed the tar and install a primetive PC board in it with all of the new caps. That was pretty easy to do. You would be surprised what they have stuff into those tar packs. Doug is right about not removing the tar it by far would be much easier to leave the tar in place. The only advantage to making a board with the caps on it is future troubleshooting of the power supply if needed. On your ground problem if you have a safe or metal window fram connect the ground to it and your resception will be much better, we connected the ground to an old gas pump door. It worked great. A wire antenna around 10/15 feet long should work fine. The buzz can easily be caused by what CV and Doug said so find a good ground even the frame if metal on your drop sealing if you have one will work. If you want to know how to go about rebuilding your power supply I can help you out big time on that. Kept all of my notes. LOL The radio we did for the show turned out beyond our wildest dreams, it was stunning. I'll try to keep an eye out for the thread and help you with any questions you might have. Best 2 U, George T
:
Hey Thanks for all the Info, But Iv already done an extensive rebuild on the power supley, at some point some one broke out a lot of tar and for some reason used a couple of big paper caps on the wrong wires, I found that in this one that all the caps wires are in one tar bin and the coils are in the others, so I cut out all the wires from the old caps and put new one in place just left them out and solder to the old posts.

:::On a TRF, one end of the antenna coil goes to the antenna, and the other is connected to ground, which completes the RF circuit. Connecting earth ground to either end but leaving the other end disconnected, usually won't give the best reception than if they are both connected correctly.
:::
:::Study this AK-37 schematic: http://www.atwaterkent.info/TechData/Drawings/Images/AK09500sch.pdf
:::

:::An AC-powered set like yours may become somewhat self-grounded by virtue of the stray capacitance between the transformer and the metal chassis/cabinet. Ideally, you should connect the water pipe to chassis ground and the antenna wire to the antenna terminal.
:::
:::Your "buzz" may be due to leaky filter caps in the power supply. Often, the filter caps are OK, but they are paper, and subject to failure. You can disconnect the existing caps and haywire replacements inside the power pack can - without removing the tar.
:::
::Hi Ray, I restored an AK 37 Moderne for the TV show "American Restoration" on the History Channel. The chassis was a total mess. I think every Rat and their kin folk lived in that chassis for the last 50/60 years. All of the wireing and coils were eaten. With Warrans help I removed the tar and install a primetive PC board in it with all of the new caps. That was pretty easy to do. You would be surprised what they have stuff into those tar packs. Doug is right about not removing the tar it by far would be much easier to leave the tar in place. The only advantage to making a board with the caps on it is future troubleshooting of the power supply if needed. On your ground problem if you have a safe or metal window fram connect the ground to it and your resception will be much better, we connected the ground to an old gas pump door. It worked great. A wire antenna around 10/15 feet long should work fine. The buzz can easily be caused by what CV and Doug said so find a good ground even the frame if metal on your drop sealing if you have one will work. If you want to know how to go about rebuilding your power supply I can help you out big time on that. Kept all of my notes. LOL The radio we did for the show turned out beyond our wildest dreams, it was stunning. I'll try to keep an eye out for the thread and help you with any questions you might have. Best 2 U, George T
::
:Hey Thanks for all the Info, But Iv already done an extensive rebuild on the power supley, at some point some one broke out a lot of tar and for some reason used a couple of big paper caps on the wrong wires, I found that in this one that all the caps wires are in one tar bin and the coils are in the others, so I cut out all the wires from the old caps and put new one in place just left them out and solder to the old posts.
:
I will take a look at the scamatics more on that antenna, with mine I also found that some one had hard jumper wired the resistors so I replaced all of the Glass tube ones, and re caped the rf filament and speaker filter. The one thing I was not sure of is the one cap in the power supply on the center tap of the filter chokes I used a 4.7uf 450 dcv electrolytic maybe thats a noise sorce the drawing calls for a 1.5mf? not sure of the voltage. Just for Info this one is the early modle, Im not really doing a full resto Just getting it going well and try to make it look good. After the bugs get worked out I have the E speaker that needs some love. I think this radio came from my great grandfather when he had his farm in Stowe Vt. Not 100% sure Im still looking into it. sorry getting off subject. Thanks a ton for all the info.

::::On a TRF, one end of the antenna coil goes to the antenna, and the other is connected to ground, which completes the RF circuit. Connecting earth ground to either end but leaving the other end disconnected, usually won't give the best reception than if they are both connected correctly.
::::
::::Study this AK-37 schematic: http://www.atwaterkent.info/TechData/Drawings/Images/AK09500sch.pdf
::::
:
::::An AC-powered set like yours may become somewhat self-grounded by virtue of the stray capacitance between the transformer and the metal chassis/cabinet. Ideally, you should connect the water pipe to chassis ground and the antenna wire to the antenna terminal.
::::
::::Your "buzz" may be due to leaky filter caps in the power supply. Often, the filter caps are OK, but they are paper, and subject to failure. You can disconnect the existing caps and haywire replacements inside the power pack can - without removing the tar.
::::
:::Hi Ray, I restored an AK 37 Moderne for the TV show "American Restoration" on the History Channel. The chassis was a total mess. I think every Rat and their kin folk lived in that chassis for the last 50/60 years. All of the wireing and coils were eaten. With Warrans help I removed the tar and install a primetive PC board in it with all of the new caps. That was pretty easy to do. You would be surprised what they have stuff into those tar packs. Doug is right about not removing the tar it by far would be much easier to leave the tar in place. The only advantage to making a board with the caps on it is future troubleshooting of the power supply if needed. On your ground problem if you have a safe or metal window fram connect the ground to it and your resception will be much better, we connected the ground to an old gas pump door. It worked great. A wire antenna around 10/15 feet long should work fine. The buzz can easily be caused by what CV and Doug said so find a good ground even the frame if metal on your drop sealing if you have one will work. If you want to know how to go about rebuilding your power supply I can help you out big time on that. Kept all of my notes. LOL The radio we did for the show turned out beyond our wildest dreams, it was stunning. I'll try to keep an eye out for the thread and help you with any questions you might have. Best 2 U, George T
:::
::Hey Thanks for all the Info, But Iv already done an extensive rebuild on the power supley, at some point some one broke out a lot of tar and for some reason used a couple of big paper caps on the wrong wires, I found that in this one that all the caps wires are in one tar bin and the coils are in the others, so I cut out all the wires from the old caps and put new one in place just left them out and solder to the old posts.
::
:I will take a look at the scamatics more on that antenna, with mine I also found that some one had hard jumper wired the resistors so I replaced all of the Glass tube ones, and re caped the rf filament and speaker filter. The one thing I was not sure of is the one cap in the power supply on the center tap of the filter chokes I used a 4.7uf 450 dcv electrolytic maybe thats a noise sorce the drawing calls for a 1.5mf? not sure of the voltage. Just for Info this one is the early modle, Im not really doing a full resto Just getting it going well and try to make it look good. After the bugs get worked out I have the E speaker that needs some love. I think this radio came from my great grandfather when he had his farm in Stowe Vt. Not 100% sure Im still looking into it. sorry getting off subject. Thanks a ton for all the info.
:
Hi Ray, I used a 600 volt regular cap on that one. A big yellow axil. Oh one other thing I have never got good results using the earth ground on a wall outlet. And with those old sets you usually get a buzz from wall transformer or flourescent lights like the new power savers. Best 2 U, George T

:::::On a TRF, one end of the antenna coil goes to the antenna, and the other is connected to ground, which completes the RF circuit. Connecting earth ground to either end but leaving the other end disconnected, usually won't give the best reception than if they are both connected correctly.
:::::
:::::Study this AK-37 schematic: http://www.atwaterkent.info/TechData/Drawings/Images/AK09500sch.pdf
:::::
::
:::::An AC-powered set like yours may become somewhat self-grounded by virtue of the stray capacitance between the transformer and the metal chassis/cabinet. Ideally, you should connect the water pipe to chassis ground and the antenna wire to the antenna terminal.
:::::
:::::Your "buzz" may be due to leaky filter caps in the power supply. Often, the filter caps are OK, but they are paper, and subject to failure. You can disconnect the existing caps and haywire replacements inside the power pack can - without removing the tar.
:::::
::::Hi Ray, I restored an AK 37 Moderne for the TV show "American Restoration" on the History Channel. The chassis was a total mess. I think every Rat and their kin folk lived in that chassis for the last 50/60 years. All of the wireing and coils were eaten. With Warrans help I removed the tar and install a primetive PC board in it with all of the new caps. That was pretty easy to do. You would be surprised what they have stuff into those tar packs. Doug is right about not removing the tar it by far would be much easier to leave the tar in place. The only advantage to making a board with the caps on it is future troubleshooting of the power supply if needed. On your ground problem if you have a safe or metal window fram connect the ground to it and your resception will be much better, we connected the ground to an old gas pump door. It worked great. A wire antenna around 10/15 feet long should work fine. The buzz can easily be caused by what CV and Doug said so find a good ground even the frame if metal on your drop sealing if you have one will work. If you want to know how to go about rebuilding your power supply I can help you out big time on that. Kept all of my notes. LOL The radio we did for the show turned out beyond our wildest dreams, it was stunning. I'll try to keep an eye out for the thread and help you with any questions you might have. Best 2 U, George T
::::
:::Hey Thanks for all the Info, But Iv already done an extensive rebuild on the power supley, at some point some one broke out a lot of tar and for some reason used a couple of big paper caps on the wrong wires, I found that in this one that all the caps wires are in one tar bin and the coils are in the others, so I cut out all the wires from the old caps and put new one in place just left them out and solder to the old posts.
:::
::I will take a look at the scamatics more on that antenna, with mine I also found that some one had hard jumper wired the resistors so I replaced all of the Glass tube ones, and re caped the rf filament and speaker filter. The one thing I was not sure of is the one cap in the power supply on the center tap of the filter chokes I used a 4.7uf 450 dcv electrolytic maybe thats a noise sorce the drawing calls for a 1.5mf? not sure of the voltage. Just for Info this one is the early modle, Im not really doing a full resto Just getting it going well and try to make it look good. After the bugs get worked out I have the E speaker that needs some love. I think this radio came from my great grandfather when he had his farm in Stowe Vt. Not 100% sure Im still looking into it. sorry getting off subject. Thanks a ton for all the info.
::
:Hi Ray, I used a 600 volt regular cap on that one. A big yellow axil. Oh one other thing I have never got good results using the earth ground on a wall outlet. And with those old sets you usually get a buzz from wall transformer or flourescent lights like the new power savers. Best 2 U, George T
:
Hi Again Ray, Check out this site and look at figure 5. That is what I ended up using on my rebuild. http://www.atwaterkent.info/Articles/AKPower.pdf
George T

::::::On a TRF, one end of the antenna coil goes to the antenna, and the other is connected to ground, which completes the RF circuit. Connecting earth ground to either end but leaving the other end disconnected, usually won't give the best reception than if they are both connected correctly.
::::::
::::::Study this AK-37 schematic: http://www.atwaterkent.info/TechData/Drawings/Images/AK09500sch.pdf
::::::
:::
::::::An AC-powered set like yours may become somewhat self-grounded by virtue of the stray capacitance between the transformer and the metal chassis/cabinet. Ideally, you should connect the water pipe to chassis ground and the antenna wire to the antenna terminal.
::::::
::::::Your "buzz" may be due to leaky filter caps in the power supply. Often, the filter caps are OK, but they are paper, and subject to failure. You can disconnect the existing caps and haywire replacements inside the power pack can - without removing the tar.
::::::
:::::Hi Ray, I restored an AK 37 Moderne for the TV show "American Restoration" on the History Channel. The chassis was a total mess. I think every Rat and their kin folk lived in that chassis for the last 50/60 years. All of the wireing and coils were eaten. With Warrans help I removed the tar and install a primetive PC board in it with all of the new caps. That was pretty easy to do. You would be surprised what they have stuff into those tar packs. Doug is right about not removing the tar it by far would be much easier to leave the tar in place. The only advantage to making a board with the caps on it is future troubleshooting of the power supply if needed. On your ground problem if you have a safe or metal window fram connect the ground to it and your resception will be much better, we connected the ground to an old gas pump door. It worked great. A wire antenna around 10/15 feet long should work fine. The buzz can easily be caused by what CV and Doug said so find a good ground even the frame if metal on your drop sealing if you have one will work. If you want to know how to go about rebuilding your power supply I can help you out big time on that. Kept all of my notes. LOL The radio we did for the show turned out beyond our wildest dreams, it was stunning. I'll try to keep an eye out for the thread and help you with any questions you might have. Best 2 U, George T
:::::
::::Hey Thanks for all the Info, But Iv already done an extensive rebuild on the power supley, at some point some one broke out a lot of tar and for some reason used a couple of big paper caps on the wrong wires, I found that in this one that all the caps wires are in one tar bin and the coils are in the others, so I cut out all the wires from the old caps and put new one in place just left them out and solder to the old posts.
::::
:::I will take a look at the scamatics more on that antenna, with mine I also found that some one had hard jumper wired the resistors so I replaced all of the Glass tube ones, and re caped the rf filament and speaker filter. The one thing I was not sure of is the one cap in the power supply on the center tap of the filter chokes I used a 4.7uf 450 dcv electrolytic maybe thats a noise sorce the drawing calls for a 1.5mf? not sure of the voltage. Just for Info this one is the early modle, Im not really doing a full resto Just getting it going well and try to make it look good. After the bugs get worked out I have the E speaker that needs some love. I think this radio came from my great grandfather when he had his farm in Stowe Vt. Not 100% sure Im still looking into it. sorry getting off subject. Thanks a ton for all the info.
:::
::Hi Ray, I used a 600 volt regular cap on that one. A big yellow axil. Oh one other thing I have never got good results using the earth ground on a wall outlet. And with those old sets you usually get a buzz from wall transformer or flourescent lights like the new power savers. Best 2 U, George T
::
:Hi Again Ray, Check out this site and look at figure 5. That is what I ended up using on my rebuild. http://www.atwaterkent.info/Articles/AKPower.pdf
:George T
:
Was that the modern drawing or old one, they are very diff., I used the drawing and spec from this site. I did refer to the modern drawing but found it hard to understand. The modern drawing from what I can tell has the b+ caps reverse and tied to the center tap of both the filter chokes and the hi voltage coil? The 1.0 mf not used in the 37. In the modern drawing It looks like the 1.5 would not be used from what I can see Im not sure that right?

:::::On a TRF, one end of the antenna coil goes to the antenna, and the other is connected to ground, which completes the RF circuit. Connecting earth ground to either end but leaving the other end disconnected, usually won't give the best reception than if they are both connected correctly.
:::::
:::::Study this AK-37 schematic: http://www.atwaterkent.info/TechData/Drawings/Images/AK09500sch.pdf
:::::
::
:::::An AC-powered set like yours may become somewhat self-grounded by virtue of the stray capacitance between the transformer and the metal chassis/cabinet. Ideally, you should connect the water pipe to chassis ground and the antenna wire to the antenna terminal.
:::::
:::::Your "buzz" may be due to leaky filter caps in the power supply. Often, the filter caps are OK, but they are paper, and subject to failure. You can disconnect the existing caps and haywire replacements inside the power pack can - without removing the tar.
:::::
::::Hi Ray, I restored an AK 37 Moderne for the TV show "American Restoration" on the History Channel. The chassis was a total mess. I think every Rat and their kin folk lived in that chassis for the last 50/60 years. All of the wireing and coils were eaten. With Warrans help I removed the tar and install a primetive PC board in it with all of the new caps. That was pretty easy to do. You would be surprised what they have stuff into those tar packs. Doug is right about not removing the tar it by far would be much easier to leave the tar in place. The only advantage to making a board with the caps on it is future troubleshooting of the power supply if needed. On your ground problem if you have a safe or metal window fram connect the ground to it and your resception will be much better, we connected the ground to an old gas pump door. It worked great. A wire antenna around 10/15 feet long should work fine. The buzz can easily be caused by what CV and Doug said so find a good ground even the frame if metal on your drop sealing if you have one will work. If you want to know how to go about rebuilding your power supply I can help you out big time on that. Kept all of my notes. LOL The radio we did for the show turned out beyond our wildest dreams, it was stunning. I'll try to keep an eye out for the thread and help you with any questions you might have. Best 2 U, George T
::::
:::Hey Thanks for all the Info, But Iv already done an extensive rebuild on the power supley, at some point some one broke out a lot of tar and for some reason used a couple of big paper caps on the wrong wires, I found that in this one that all the caps wires are in one tar bin and the coils are in the others, so I cut out all the wires from the old caps and put new one in place just left them out and solder to the old posts.
:::
::I will take a look at the scamatics more on that antenna, with mine I also found that some one had hard jumper wired the resistors so I replaced all of the Glass tube ones, and re caped the rf filament and speaker filter. The one thing I was not sure of is the one cap in the power supply on the center tap of the filter chokes I used a 4.7uf 450 dcv electrolytic maybe thats a noise sorce the drawing calls for a 1.5mf? not sure of the voltage. Just for Info this one is the early modle, Im not really doing a full resto Just getting it going well and try to make it look good. After the bugs get worked out I have the E speaker that needs some love. I think this radio came from my great grandfather when he had his farm in Stowe Vt. Not 100% sure Im still looking into it. sorry getting off subject. Thanks a ton for all the info.
::
:Hi Ray, I used a 600 volt regular cap on that one. A big yellow axil. Oh one other thing I have never got good results using the earth ground on a wall outlet. And with those old sets you usually get a buzz from wall transformer or flourescent lights like the new power savers. Best 2 U, George T
:
I used an electrolytic because I read some were as a rule of thumb anything over 1.0 normaly was. Maybe I will try a reg, want to try tubes first thats most likley whats wrong Iv run into that a couple times.

One major source of BC radio "buzz" is SCR incandescent light dimmers. Got any of those in your residence? If you are an apartment dweller, adjacent units with dimmers can be a source of the noise, also.

:One major source of BC radio "buzz" is SCR incandescent light dimmers. Got any of those in your residence? If you are an apartment dweller, adjacent units with dimmers can be a source of the noise, also.
:
No light dimmers, but I am amazed at how many things Inter fear with all the old radios I have like a cordless phone, the clock on my cook stove when its plug in to the same out let circuit, the list goes on, wonder if all this stuff is why every one seems sick these days?

One way to figure out if the source of the "buzz" is within the radio (bad filter caps) or outside, is to disconnect the set's antenna and use a very short wire to jumper the antenna input terminal to the ground terminal. If the set still is noisy, the noise is probably being generated inside the set. If the noise vanishes, start looking for RF noise generators in your home.

Another source of RF noise is the home computer. These use switching power supplies which can generate a lot of RF artifacts. This noise is conducted to the mains lines and gets radiated throughout the house. About the only thing that can be done (short of turning off the computer) is to install an RF suppressor module right at the wall outlet where the computer is plugged in.

Hum from the 60-Hz power supply will be either 60-Hz or 120-Hz. Learn how to identify them. I claim to be a tenor, and can easily hum to match 120 Hz. For 60 Hz, it's a bit of a stretch.

To me, a buzz is more of a noise than a pure hum.

:Hum from the 60-Hz power supply will be either 60-Hz or 120-Hz. Learn how to identify them. I claim to be a tenor, and can easily hum to match 120 Hz. For 60 Hz, it's a bit of a stretch.
:
:To me, a buzz is more of a noise than a pure hum.
:
Do you have a good way to tell the diff? Another clue is when I turn the radio on its very slight or low then after a few seconds it gets louder the when it warms up it goes some where inbetween and stays, more of a buzz than a hum? The stations tune the noise out but its there when the volume all the way down.

On an old AK speaker, power supply hum can sound a lot like a "buzz"; the reason being that the low-frequency response of the speaker is poor and breakup (distortion) can occur at low frequencies.

FWIW, a "buzz" is considered to be a harsh, ragged tone; a "hum" is a very pure tone. In a set with a decent speaker (i.e., a radio manufactured after about 1930), the two tone types are easily distinguishable from each other. These meanings get blurred with early speakers for the reason stated above.

But the fact that the noise is there with the volume turned off is significant: almost certainly it is power-supply hum if it is present with the volume "off". Some PS hum is normal; but if you can distinctly hear it from more than three feet away with the volume set at zero, it indicates that the B+ filter caps need replacement.

:On an old AK speaker, power supply hum can sound a lot like a "buzz"; the reason being that the low-frequency response of the speaker is poor and breakup (distortion) can occur at low frequencies.
:
:FWIW, a "buzz" is considered to be a harsh, ragged tone; a "hum" is a very pure tone. In a set with a decent speaker (i.e., a radio manufactured after about 1930), the two tone types are easily distinguishable from each other. These meanings get blurred with early speakers for the reason stated above.
:
:But the fact that the noise is there with the volume turned off is significant: almost certainly it is power-supply hum if it is present with the volume "off". Some PS hum is normal; but if you can distinctly hear it from more than three feet away with the volume set at zero, it indicates that the B+ filter caps need replacement.
:
The B+ caps have been replace could it be the electrolytic cap on the center tap? they all ground together.