Jeff,
What your Zenith "expert" is recommending is exactly what Norm has already suggested. The only difference is that instead of adding a 47-ohm resistor in series with the silicon diode and the existing 130-ohm resistor, he is removing the original 130-ohm resistor and replacing it with a single larger one. (130 + 47 = 177 ohms, which is close to the 180 ohms he recommends.) Either way will work just fine. But going as high as 220-ohms is not always wise, for reasons mentioned below, although this depends on prevailing line voltage.
The recommendation to target 7.6 - 8.4 volts across the filament string is pretty much right. But my practice is to focus on the 1L6 converter only and target its filament for 1.4 volts, and not worry about the rest of the filament string. Two reasons for this: First, the 1L6 is an expensive tube and excessive filament voltage (1.5 volts or above) will shorten its lifespan; Second, too little voltage (below 1.3 volts) at the 1L6 will stop oscillator function. In my experience, low voltage to the oscillator section of the 1L6 is the single most common cause of T-O reception problems. If you plan to add as much as 220-ohms series resistance, depending on the line voltage at which your T-O will be operated you should check to make sure that the filament voltage at the 1L6 does not fall below 1.4 volts.
Poston
:Thanks to both of you. I will get a few of these for my bench stock.
:
:I also contacted another Zenith expert and he recommended that, at the same time, I replace the 130 ohm 3w resistor with a 180-220 ohm 5 watt (He says the target is 7.6-8.4 v across the filament string) Depending upon home voltage i.e. 123-125v and he likes to "pamper" filaments so he uses a 220 ohm.
:Hope this helps others.
:
:Jeff W
:
:
:::I totally agree with Norm. Don't worry about testing it, just replace it. I would go with a 1N4007 diode. The few pennies more in cost are neglible and the 1000 V. rating ensures more than enough margin.
::
::Selenium rectifiers haven't been used in production radios for about 40 years and trying to find a working replacment selenium unit just isn't worth the trouble. When I worked for Westinghouse many years ago, we helped a customer change an electrochemical plating rectifier from selenium to silicon. We replaced a cubic yard of selenium units with a silicon unit about 25 times smaller!
::
::Hi Jeff
:::
::: It's best to replace the selenium rectifier with a 1N4004-1N4007 silicon diode and 47 ohm 1 watt or greater series resistor. Over time selenium rectifier have increased voltage drop. A new selenium rectifier should have a 7 volt drop under load according to Federal, manufacturer.
:::
::: You don't want to have one of these burn. You will never forget the smell.
:::
:::Norm
:::
::::
:::
:::Greetings,
::::
::::I am working on an H500 and would like to insure the rectifier is working correctly. I have never tested one before. I imagine that it should provide only DC at the output and no AC should be there? Under load tests? Standard diode tests? Any suggestions on how to test thoroughly? I have a Digital Multi Meter. I have seen test devices specifically for such rectifiers but do not own one. Thanks in advance.
::::
::::Jeff W
The cathode, band end, of the diode should connect the same place as + on your original selinium rectifier. The placement of added resistor doesn't matter as long as it's in series. Your location for the resistor is correct..
The important thing is diode band end goes toward positive on filter caps not AC line.
Norm
:Hello Norm, Poston and All,
:I finally got my IN4007 diodes and 47 ohm 5W resistors. Just want to make sure I assemble this correctly. The band on the diode (cathode end -) should face away from the existing 130 Ohm divided resistor. And the 47 Ohm resistor should go between the diode and the 130 ohm resistor. Correct? I copied last month's text below for reference.
:Jeff
:
:Jeff,
:What your Zenith "expert" is recommending is exactly what Norm has already suggested. The only difference is that instead of adding a 47-ohm resistor in series with the silicon diode and the existing 130-ohm resistor, he is removing the original 130-ohm resistor and replacing it with a single larger one. (130 + 47 = 177 ohms, which is close to the 180 ohms he recommends.) Either way will work just fine. But going as high as 220-ohms is not always wise, for reasons mentioned below, although this depends on prevailing line voltage.
:The recommendation to target 7.6 - 8.4 volts across the filament string is pretty much right. But my practice is to focus on the 1L6 converter only and target its filament for 1.4 volts, and not worry about the rest of the filament string. Two reasons for this: First, the 1L6 is an expensive tube and excessive filament voltage (1.5 volts or above) will shorten its lifespan; Second, too little voltage (below 1.3 volts) at the 1L6 will stop oscillator function. In my experience, low voltage to the oscillator section of the 1L6 is the single most common cause of T-O reception problems. If you plan to add as much as 220-ohms series resistance, depending on the line voltage at which your T-O will be operated you should check to make sure that the filament voltage at the 1L6 does not fall below 1.4 volts.
:
:Poston
:
:
:
::Thanks to both of you. I will get a few of these for my bench stock.
::
::I also contacted another Zenith expert and he recommended that, at the same time, I replace the 130 ohm 3w resistor with a 180-220 ohm 5 watt (He says the target is 7.6-8.4 v across the filament string) Depending upon home voltage i.e. 123-125v and he likes to "pamper" filaments so he uses a 220 ohm.
::Hope this helps others.
::
::Jeff W
::
::
::::I totally agree with Norm. Don't worry about testing it, just replace it. I would go with a 1N4007 diode. The few pennies more in cost are neglible and the 1000 V. rating ensures more than enough margin.
:::
:::Selenium rectifiers haven't been used in production radios for about 40 years and trying to find a working replacment selenium unit just isn't worth the trouble. When I worked for Westinghouse many years ago, we helped a customer change an electrochemical plating rectifier from selenium to silicon. We replaced a cubic yard of selenium units with a silicon unit about 25 times smaller!
:::
:::Hi Jeff
::::
:::: It's best to replace the selenium rectifier with a 1N4004-1N4007 silicon diode and 47 ohm 1 watt or greater series resistor. Over time selenium rectifier have increased voltage drop. A new selenium rectifier should have a 7 volt drop under load according to Federal, manufacturer.
::::
:::: You don't want to have one of these burn. You will never forget the smell.
::::
::::Norm
::::
:::::
::::
::::Greetings,
:::::
:::::I am working on an H500 and would like to insure the rectifier is working correctly. I have never tested one before. I imagine that it should provide only DC at the output and no AC should be there? Under load tests? Standard diode tests? Any suggestions on how to test thoroughly? I have a Digital Multi Meter. I have seen test devices specifically for such rectifiers but do not own one. Thanks in advance.
:::::
:::::Jeff W
:
The only thing I would add is that you do not need to remove your old selenium rectifier from the chassis. Just disconnect one of its terminals (which will isolate it from the circuit) and use the remaining terminal for a connection point for your new components. It does not matter which terminal of the old selenium which you disconnect, but usually leaving the one connected to the large 130 ohm resistor will be the easiest.
Good luck, and if you have further questions do not hesitate to ask.
Poston
:Hi Jeff
:
: The cathode, band end, of the diode should connect the same place as + on your original selinium rectifier. The placement of added resistor doesn't matter as long as it's in series. Your location for the resistor is correct..
:
: The important thing is diode band end goes toward positive on filter caps not AC line.
:
:Norm
:
::Hello Norm, Poston and All,
::I finally got my IN4007 diodes and 47 ohm 5W resistors. Just want to make sure I assemble this correctly. The band on the diode (cathode end -) should face away from the existing 130 Ohm divided resistor. And the 47 Ohm resistor should go between the diode and the 130 ohm resistor. Correct? I copied last month's text below for reference.
::Jeff
::
::Jeff,
::What your Zenith "expert" is recommending is exactly what Norm has already suggested. The only difference is that instead of adding a 47-ohm resistor in series with the silicon diode and the existing 130-ohm resistor, he is removing the original 130-ohm resistor and replacing it with a single larger one. (130 + 47 = 177 ohms, which is close to the 180 ohms he recommends.) Either way will work just fine. But going as high as 220-ohms is not always wise, for reasons mentioned below, although this depends on prevailing line voltage.
::The recommendation to target 7.6 - 8.4 volts across the filament string is pretty much right. But my practice is to focus on the 1L6 converter only and target its filament for 1.4 volts, and not worry about the rest of the filament string. Two reasons for this: First, the 1L6 is an expensive tube and excessive filament voltage (1.5 volts or above) will shorten its lifespan; Second, too little voltage (below 1.3 volts) at the 1L6 will stop oscillator function. In my experience, low voltage to the oscillator section of the 1L6 is the single most common cause of T-O reception problems. If you plan to add as much as 220-ohms series resistance, depending on the line voltage at which your T-O will be operated you should check to make sure that the filament voltage at the 1L6 does not fall below 1.4 volts.
::
::Poston
::
::
::
:::Thanks to both of you. I will get a few of these for my bench stock.
:::
:::I also contacted another Zenith expert and he recommended that, at the same time, I replace the 130 ohm 3w resistor with a 180-220 ohm 5 watt (He says the target is 7.6-8.4 v across the filament string) Depending upon home voltage i.e. 123-125v and he likes to "pamper" filaments so he uses a 220 ohm.
:::Hope this helps others.
:::
:::Jeff W
:::
:::
:::::I totally agree with Norm. Don't worry about testing it, just replace it. I would go with a 1N4007 diode. The few pennies more in cost are neglible and the 1000 V. rating ensures more than enough margin.
::::
::::Selenium rectifiers haven't been used in production radios for about 40 years and trying to find a working replacment selenium unit just isn't worth the trouble. When I worked for Westinghouse many years ago, we helped a customer change an electrochemical plating rectifier from selenium to silicon. We replaced a cubic yard of selenium units with a silicon unit about 25 times smaller!
::::
::::Hi Jeff
:::::
::::: It's best to replace the selenium rectifier with a 1N4004-1N4007 silicon diode and 47 ohm 1 watt or greater series resistor. Over time selenium rectifier have increased voltage drop. A new selenium rectifier should have a 7 volt drop under load according to Federal, manufacturer.
:::::
::::: You don't want to have one of these burn. You will never forget the smell.
:::::
:::::Norm
:::::
::::::
:::::
:::::Greetings,
::::::
::::::I am working on an H500 and would like to insure the rectifier is working correctly. I have never tested one before. I imagine that it should provide only DC at the output and no AC should be there? Under load tests? Standard diode tests? Any suggestions on how to test thoroughly? I have a Digital Multi Meter. I have seen test devices specifically for such rectifiers but do not own one. Thanks in advance.
::::::
::::::Jeff W
::
:Hi Jeff,
:Norm has already given you the answer regarding connection of your new diode and resistor.
:
:The only thing I would add is that you do not need to remove your old selenium rectifier from the chassis. Just disconnect one of its terminals (which will isolate it from the circuit) and use the remaining terminal for a connection point for your new components. It does not matter which terminal of the old selenium which you disconnect, but usually leaving the one connected to the large 130 ohm resistor will be the easiest.
:
:Good luck, and if you have further questions do not hesitate to ask.
:
:Poston
:
:
:
:
::Hi Jeff
::
:: The cathode, band end, of the diode should connect the same place as + on your original selinium rectifier. The placement of added resistor doesn't matter as long as it's in series. Your location for the resistor is correct..
::
:: The important thing is diode band end goes toward positive on filter caps not AC line.
::
::Norm
::
:::Hello Norm, Poston and All,
:::I finally got my IN4007 diodes and 47 ohm 5W resistors. Just want to make sure I assemble this correctly. The band on the diode (cathode end -) should face away from the existing 130 Ohm divided resistor. And the 47 Ohm resistor should go between the diode and the 130 ohm resistor. Correct? I copied last month's text below for reference.
:::Jeff
:::
:::Jeff,
:::What your Zenith "expert" is recommending is exactly what Norm has already suggested. The only difference is that instead of adding a 47-ohm resistor in series with the silicon diode and the existing 130-ohm resistor, he is removing the original 130-ohm resistor and replacing it with a single larger one. (130 + 47 = 177 ohms, which is close to the 180 ohms he recommends.) Either way will work just fine. But going as high as 220-ohms is not always wise, for reasons mentioned below, although this depends on prevailing line voltage.
:::The recommendation to target 7.6 - 8.4 volts across the filament string is pretty much right. But my practice is to focus on the 1L6 converter only and target its filament for 1.4 volts, and not worry about the rest of the filament string. Two reasons for this: First, the 1L6 is an expensive tube and excessive filament voltage (1.5 volts or above) will shorten its lifespan; Second, too little voltage (below 1.3 volts) at the 1L6 will stop oscillator function. In my experience, low voltage to the oscillator section of the 1L6 is the single most common cause of T-O reception problems. If you plan to add as much as 220-ohms series resistance, depending on the line voltage at which your T-O will be operated you should check to make sure that the filament voltage at the 1L6 does not fall below 1.4 volts.
:::
:::Poston
:::
:::
:::
::::Thanks to both of you. I will get a few of these for my bench stock.
::::
::::I also contacted another Zenith expert and he recommended that, at the same time, I replace the 130 ohm 3w resistor with a 180-220 ohm 5 watt (He says the target is 7.6-8.4 v across the filament string) Depending upon home voltage i.e. 123-125v and he likes to "pamper" filaments so he uses a 220 ohm.
::::Hope this helps others.
::::
::::Jeff W
::::
::::
::::::I totally agree with Norm. Don't worry about testing it, just replace it. I would go with a 1N4007 diode. The few pennies more in cost are neglible and the 1000 V. rating ensures more than enough margin.
:::::
:::::Selenium rectifiers haven't been used in production radios for about 40 years and trying to find a working replacment selenium unit just isn't worth the trouble. When I worked for Westinghouse many years ago, we helped a customer change an electrochemical plating rectifier from selenium to silicon. We replaced a cubic yard of selenium units with a silicon unit about 25 times smaller!
:::::
:::::Hi Jeff
::::::
:::::: It's best to replace the selenium rectifier with a 1N4004-1N4007 silicon diode and 47 ohm 1 watt or greater series resistor. Over time selenium rectifier have increased voltage drop. A new selenium rectifier should have a 7 volt drop under load according to Federal, manufacturer.
::::::
:::::: You don't want to have one of these burn. You will never forget the smell.
::::::
::::::Norm
::::::
:::::::
::::::
::::::Greetings,
:::::::
:::::::I am working on an H500 and would like to insure the rectifier is working correctly. I have never tested one before. I imagine that it should provide only DC at the output and no AC should be there? Under load tests? Standard diode tests? Any suggestions on how to test thoroughly? I have a Digital Multi Meter. I have seen test devices specifically for such rectifiers but do not own one. Thanks in advance.
:::::::
:::::::Jeff W
:::