I am working on a Philco 84. I have replaced all the bakelite block capactiors and I still have a loud hum. I am now planning on replacing the eltrolitytics but I cannot find a source for new ones with the appropriate values. (The values are 8 mfd and 4 mfd) It appears that I am going to have to put a set in series to get an approporate value.

If I put these in series does it reduce the voltage rateing of the individual capacitors?

Do I need to install proportioning resistors across these capactiors?

It would nice to find the right value capacitors. Does anyone know where I may get the appropriate values? AES does not have these values.

How close do the values need to be?

The capacitor values are not super critical, but because the Philco's use a higher than average supply voltage, the caps should be rated at no less than 450 WVDC.

So if you end up using 2- 10Mfd caps, this is not a problem at all. I wound up using about that value on both of my Philco consoles.

Try not to get too large a value on the cap closest to the power transformer, as it will raise the "inrush" current to point where it might burn out a filter choke.

Chances are that you will not find exact looking caps new, but that is not a major problem as I will give you the procedure to "repair" the old caps.

Your filter caps should be clamped into place, which makes things easy. Remove the caps one at a time, so that you do not get wires crossed. Put a small index mark on the can about midpoint of where the clamp grabs the can; the mark is for re-alignment on re-assembly. Use a tubing cutter to slice the can at about the same distance; midpoint of clamping location. Then it is a matter of peeling out the old cap's contents, and then installing your new cap inside of the shell, and place it into the mount- the paper insulator conceals the cut, the clamp holds the unit together, and you retain the original look of the radio.

When you put caps in series, you should connect the positive terminals (inside foils) together. You reduce the capacity when you do this, but if both caps are of the same value, you increase the working voltage. For the sake of a safety margin, 2- 300WVDC caps connected in this manner( these would be the lowest working voltage I would consider using to replace a 450WVDC cap- which I have done). There should be no need to add any resistors provided the old resistors have not changed value over the years.

The design is actually quite sensitive, and the selectivity is high too.
I am assuming you may have checked out Chuck Schwark's Philco Pages, but if not, they are an excellent Philco source.

: I am working on a Philco 84. I have replaced all the bakelite block capactiors and I still have a loud hum. I am now planning on replacing the eltrolitytics but I cannot find a source for new ones with the appropriate values. (The values are 8 mfd and 4 mfd) It appears that I am going to have to put a set in series to get an approporate value.

: If I put these in series does it reduce the voltage rateing of the individual capacitors?

: Do I need to install proportioning resistors across these capactiors?

: It would nice to find the right value capacitors. Does anyone know where I may get the appropriate values? AES does not have these values.

: How close do the values need to be?

Hi

Use 2 - 10 mfd @ 450 volt caps. Slightly larger than the original will minimize hum and will not damage the radio.

Disconnect the originals but leave the caps mounted on the chassis. Install new caps under the chassis. They will be much smaller in size.

Norm

: The capacitor values are not super critical, but because the Philco's use a higher than average supply voltage, the caps should be rated at no less than 450 WVDC.

: So if you end up using 2- 10Mfd caps, this is not a problem at all. I wound up using about that value on both of my Philco consoles.

: Try not to get too large a value on the cap closest to the power transformer, as it will raise the "inrush" current to point where it might burn out a filter choke.

: Chances are that you will not find exact looking caps new, but that is not a major problem as I will give you the procedure to "repair" the old caps.

: Your filter caps should be clamped into place, which makes things easy. Remove the caps one at a time, so that you do not get wires crossed. Put a small index mark on the can about midpoint of where the clamp grabs the can; the mark is for re-alignment on re-assembly. Use a tubing cutter to slice the can at about the same distance; midpoint of clamping location. Then it is a matter of peeling out the old cap's contents, and then installing your new cap inside of the shell, and place it into the mount- the paper insulator conceals the cut, the clamp holds the unit together, and you retain the original look of the radio.

: When you put caps in series, you should connect the positive terminals (inside foils) together. You reduce the capacity when you do this, but if both caps are of the same value, you increase the working voltage. For the sake of a safety margin, 2- 300WVDC caps connected in this manner( these would be the lowest working voltage I would consider using to replace a 450WVDC cap- which I have done). There should be no need to add any resistors provided the old resistors have not changed value over the years.

: The design is actually quite sensitive, and the selectivity is high too.
: I am assuming you may have checked out Chuck Schwark's Philco Pages, but if not, they are an excellent Philco source.

: : I am working on a Philco 84. I have replaced all the bakelite block capactiors and I still have a loud hum. I am now planning on replacing the eltrolitytics but I cannot find a source for new ones with the appropriate values. (The values are 8 mfd and 4 mfd) It appears that I am going to have to put a set in series to get an approporate value.

: : If I put these in series does it reduce the voltage rateing of the individual capacitors?

: : Do I need to install proportioning resistors across these capactiors?

: : It would nice to find the right value capacitors. Does anyone know where I may get the appropriate values? AES does not have these values.

: : How close do the values need to be?

Hello,
You wrote:
"When you put caps in series, you should connect the positive terminals (inside foils) together."
I don't believe this is the correct way to put polarized capacitors in series. Two electrolytic capacitors in series still need to be polarized, so, plus to minus is appropriate. Could someone comment.
Thanks,
Charles

: Hi

: Use 2 - 10 mfd @ 450 volt caps. Slightly larger than the original will minimize hum and will not damage the radio.

: Disconnect the originals but leave the caps mounted on the chassis. Install new caps under the chassis. They will be much smaller in size.

: Norm

:
: : The capacitor values are not super critical, but because the Philco's use a higher than average supply voltage, the caps should be rated at no less than 450 WVDC.

: : So if you end up using 2- 10Mfd caps, this is not a problem at all. I wound up using about that value on both of my Philco consoles.

: : Try not to get too large a value on the cap closest to the power transformer, as it will raise the "inrush" current to point where it might burn out a filter choke.

: : Chances are that you will not find exact looking caps new, but that is not a major problem as I will give you the procedure to "repair" the old caps.

: : Your filter caps should be clamped into place, which makes things easy. Remove the caps one at a time, so that you do not get wires crossed. Put a small index mark on the can about midpoint of where the clamp grabs the can; the mark is for re-alignment on re-assembly. Use a tubing cutter to slice the can at about the same distance; midpoint of clamping location. Then it is a matter of peeling out the old cap's contents, and then installing your new cap inside of the shell, and place it into the mount- the paper insulator conceals the cut, the clamp holds the unit together, and you retain the original look of the radio.

: : When you put caps in series, you should connect the positive terminals (inside foils) together. You reduce the capacity when you do this, but if both caps are of the same value, you increase the working voltage. For the sake of a safety margin, 2- 300WVDC caps connected in this manner( these would be the lowest working voltage I would consider using to replace a 450WVDC cap- which I have done). There should be no need to add any resistors provided the old resistors have not changed value over the years.

: : The design is actually quite sensitive, and the selectivity is high too.
: : I am assuming you may have checked out Chuck Schwark's Philco Pages, but if not, they are an excellent Philco source.

: : : I am working on a Philco 84. I have replaced all the bakelite block capactiors and I still have a loud hum. I am now planning on replacing the eltrolitytics but I cannot find a source for new ones with the appropriate values. (The values are 8 mfd and 4 mfd) It appears that I am going to have to put a set in series to get an approporate value.

: : : If I put these in series does it reduce the voltage rateing of the individual capacitors?

: : : Do I need to install proportioning resistors across these capactiors?

: : : It would nice to find the right value capacitors. Does anyone know where I may get the appropriate values? AES does not have these values.

: : : How close do the values need to be?

Hi Charles

Here is my comment about electrolytic capacitors in series.

In order to make a higher voltage electrolytic capacitor two of the same value and voltage may be put in series. The plus of one goes to the negative of the other. In addition it's best to add a resistor across each cap. Usually 470K will be ok. In this case voltage rating will be double.

If two capacitors are in series with positive terminals together the voltage rating will not increase however the capacitor will be non polarized.

Electrolytic caps will have some leakage. Unless resistors are installed across each one the voltage may not be divided equally between the two.

Norm

,
: You wrote:
: "When you put caps in series, you should connect the positive terminals (inside foils) together."
: I don't believe this is the correct way to put polarized capacitors in series. Two electrolytic capacitors in series still need to be polarized, so, plus to minus is appropriate. Could someone comment.
: Thanks,
: Charles

: : Hi

: : Use 2 - 10 mfd @ 450 volt caps. Slightly larger than the original will minimize hum and will not damage the radio.

: : Disconnect the originals but leave the caps mounted on the chassis. Install new caps under the chassis. They will be much smaller in size.

: : Norm

:
: :
: : : The capacitor values are not super critical, but because the Philco's use a higher than average supply voltage, the caps should be rated at no less than 450 WVDC.

: : : So if you end up using 2- 10Mfd caps, this is not a problem at all. I wound up using about that value on both of my Philco consoles.

: : : Try not to get too large a value on the cap closest to the power transformer, as it will raise the "inrush" current to point where it might burn out a filter choke.

: : : Chances are that you will not find exact looking caps new, but that is not a major problem as I will give you the procedure to "repair" the old caps.

: : : Your filter caps should be clamped into place, which makes things easy. Remove the caps one at a time, so that you do not get wires crossed. Put a small index mark on the can about midpoint of where the clamp grabs the can; the mark is for re-alignment on re-assembly. Use a tubing cutter to slice the can at about the same distance; midpoint of clamping location. Then it is a matter of peeling out the old cap's contents, and then installing your new cap inside of the shell, and place it into the mount- the paper insulator conceals the cut, the clamp holds the unit together, and you retain the original look of the radio.

: : : When you put caps in series, you should connect the positive terminals (inside foils) together. You reduce the capacity when you do this, but if both caps are of the same value, you increase the working voltage. For the sake of a safety margin, 2- 300WVDC caps connected in this manner( these would be the lowest working voltage I would consider using to replace a 450WVDC cap- which I have done). There should be no need to add any resistors provided the old resistors have not changed value over the years.

: : : The design is actually quite sensitive, and the selectivity is high too.
: : : I am assuming you may have checked out Chuck Schwark's Philco Pages, but if not, they are an excellent Philco source.

:
: : : : I am working on a Philco 84. I have replaced all the bakelite block capactiors and I still have a loud hum. I am now planning on replacing the eltrolitytics but I cannot find a source for new ones with the appropriate values. (The values are 8 mfd and 4 mfd) It appears that I am going to have to put a set in series to get an approporate value.

: : : : If I put these in series does it reduce the voltage rateing of the individual capacitors?

: : : : Do I need to install proportioning resistors across these capactiors?

: : : : It would nice to find the right value capacitors. Does anyone know where I may get the appropriate values? AES does not have these values.

: : : : How close do the values need to be?

It has been my own experience, that you do have a higher effective Working Voltage rating, but not exactly double the working voltage, and half the capacity. The positive terminals attached together give you a non-polarized capacitor, and there is some physics involved as to why the Positives are slightly better a choice than the negatives; a minor point in this application which I ommitted in this particular application. I have done this in a number of high current application where the voltage was AC, with little difficulties.

I don't think there is any need to discuss the matter any further, unless we break out the college physics books to be absolutely certain.

I am, and I was relating what my own experiences have been, and one of the things that I had done in one of my own Philcos with no problem to date.

: Hi Charles

: Here is my comment about electrolytic capacitors in series.

: In order to make a higher voltage electrolytic capacitor two of the same value and voltage may be put in series. The plus of one goes to the negative of the other. In addition it's best to add a resistor across each cap. Usually 470K will be ok. In this case voltage rating will be double.

: If two capacitors are in series with positive terminals together the voltage rating will not increase however the capacitor will be non polarized.

: Electrolytic caps will have some leakage. Unless resistors are installed across each one the voltage may not be divided equally between the two.

: Norm

: ,
: : You wrote:
: : "When you put caps in series, you should connect the positive terminals (inside foils) together."
: : I don't believe this is the correct way to put polarized capacitors in series. Two electrolytic capacitors in series still need to be polarized, so, plus to minus is appropriate. Could someone comment.
: : Thanks,
: : Charles

: : : Hi

: : : Use 2 - 10 mfd @ 450 volt caps. Slightly larger than the original will minimize hum and will not damage the radio.

: : : Disconnect the originals but leave the caps mounted on the chassis. Install new caps under the chassis. They will be much smaller in size.

: : : Norm

: :
: : :
: : : : The capacitor values are not super critical, but because the Philco's use a higher than average supply voltage, the caps should be rated at no less than 450 WVDC.

: : : : So if you end up using 2- 10Mfd caps, this is not a problem at all. I wound up using about that value on both of my Philco consoles.

: : : : Try not to get too large a value on the cap closest to the power transformer, as it will raise the "inrush" current to point where it might burn out a filter choke.

: : : : Chances are that you will not find exact looking caps new, but that is not a major problem as I will give you the procedure to "repair" the old caps.

: : : : Your filter caps should be clamped into place, which makes things easy. Remove the caps one at a time, so that you do not get wires crossed. Put a small index mark on the can about midpoint of where the clamp grabs the can; the mark is for re-alignment on re-assembly. Use a tubing cutter to slice the can at about the same distance; midpoint of clamping location. Then it is a matter of peeling out the old cap's contents, and then installing your new cap inside of the shell, and place it into the mount- the paper insulator conceals the cut, the clamp holds the unit together, and you retain the original look of the radio.

: : : : When you put caps in series, you should connect the positive terminals (inside foils) together. You reduce the capacity when you do this, but if both caps are of the same value, you increase the working voltage. For the sake of a safety margin, 2- 300WVDC caps connected in this manner( these would be the lowest working voltage I would consider using to replace a 450WVDC cap- which I have done). There should be no need to add any resistors provided the old resistors have not changed value over the years.

: : : : The design is actually quite sensitive, and the selectivity is high too.
: : : : I am assuming you may have checked out Chuck Schwark's Philco Pages, but if not, they are an excellent Philco source.

: :
: : : : : I am working on a Philco 84. I have replaced all the bakelite block capactiors and I still have a loud hum. I am now planning on replacing the eltrolitytics but I cannot find a source for new ones with the appropriate values. (The values are 8 mfd and 4 mfd) It appears that I am going to have to put a set in series to get an approporate value.

: : : : : If I put these in series does it reduce the voltage rateing of the individual capacitors?

: : : : : Do I need to install proportioning resistors across these capactiors?

: : : : : It would nice to find the right value capacitors. Does anyone know where I may get the appropriate values? AES does not have these values.

: : : : : How close do the values need to be?

what size cap or sizes would i need to convert about 18volts into about 200 volts? is there a away i could bridge caps together or do they make caps that will do that i need some help plz e mail me thanx
Boardlikehell52@hotmail.com

: I am working on a Philco 84. I have replaced all the bakelite block capactiors and I still have a loud hum. I am now planning on replacing the eltrolitytics but I cannot find a source for new ones with the appropriate values. (The values are 8 mfd and 4 mfd) It appears that I am going to have to put a set in series to get an approporate value.

: If I put these in series does it reduce the voltage rateing of the individual capacitors?

: Do I need to install proportioning resistors across these capactiors?

: It would nice to find the right value capacitors. Does anyone know where I may get the appropriate values? AES does not have these values.

: How close do the values need to be?
There are a couple of things to watch for when placing electrolytics in series:
1. Match the values with a capacitance meter since electrolytics have a rather high capacitance variance.

2. The smaller series cap will always have the highest voltage appearing
across it - even with no leakage. In fact the voltage
will vary inversely with the square of the capacitance.

Hi Jeff,
I posted some comments on this the other day but they seem to have got lost. I agree 100% with Norm Leal. If you put the electros in series with the positive poles together they can form a psuedo non polarised capacitor, thoug I'd use one specifically designed for AC. When used on DC the reversed polarity capacitor will tend to be charged by the leakage current of the other, if resistors are placed across each capacitor in this case it will make this worse. The voltage rating will not be increased as the only way the extra voltage can be dropped across the capacitors is to exceed the voltage rating on the correctly polarised capacitor or across the other in reverse polarity. It will make no difference if the positive terminals or negative terminals are joined, in a series circuit the current flowing is the same through the whole series circuit. When the capacitors are joined positive to negative similar to torch cells, the DC voltage will devide between them in proportion to their individual leakage
resistance and their combined capacitance will be reduced by the normal formula for capacitors in series, Ctotal = (C1xC2)/(C1+C2) for two capacitors. When they are equal value the capacitance is halved. It's good practice to place a resistor across each capacitor to ensure the voltage is divided equally, then the voltage rating is almost doubled (there may be a slight imbalance in the voltage across each that will reduce the rating from double). The rsistors are typically about 470 k and need adequate voltage and power ratings, metal film 1 to 2 watt are very suitable. The normal use for electrolytics is for power supply filtering and it's not usually necessary to reduce the capacitance by series connection for this purpose, if they're too large, within reason it does more good than harm. Where they are often series connected is in high voltage power supplies to achieve adequate voltage rating. If you want to see examples of this go to the library and look in the ARRL handbook at Transmitter power supplies, they often use several in series to get the high voltage rating needed for supplies that can be several kilo volts. Joining them in opposition will probably work because the working voltage is less than the rating of each capacitor and the leakage resistance is higher in the correct direction, forcing most of the voltage to drop across the correctly polarised capacitor, however the life of the other may be shortened by this mode of operation. Don Black.
: I am working on a Philco 84. I have replaced all the bakelite block capactiors and I still have a loud hum. I am now planning on replacing the eltrolitytics but I cannot find a source for new ones with the appropriate values. (The values are 8 mfd and 4 mfd) It appears that I am going to have to put a set in series to get an approporate value.

: If I put these in series does it reduce the voltage rateing of the individual capacitors?

: Do I need to install proportioning resistors across these capactiors?

: It would nice to find the right value capacitors. Does anyone know where I may get the appropriate values? AES does not have these values.

: How close do the values need to be?

Gentlemen,

It sounds like we have had a good "discussion" but I am still humming. I think that my rectifier tube is toast. I do not have a tube tester that will test the older type tubes though I have bought one through ebay and will be receiving it within the next week or so I will be able to test the rectifier and the output. (The other two I replaced. They where cheep).

I have an old radio handbook that was published in 1941. It has a couple pages covering capacitors as they relate to radios, series and parallel connections, polarity and equalizing resistors. If anyone would like me to email a scanned copy of these pages please email.

I was really looking for input on the size of capacitor that I could get away with (On my original question) and a second opinion on how to do it.

Thanks Everyone

Jeff

: I am working on a Philco 84. I have replaced all the bakelite block capactiors and I still have a loud hum. I am now planning on replacing the eltrolitytics but I cannot find a source for new ones with the appropriate values. (The values are 8 mfd and 4 mfd) It appears that I am going to have to put a set in series to get an approporate value.

: If I put these in series does it reduce the voltage rateing of the individual capacitors?

: Do I need to install proportioning resistors across these capactiors?

: It would nice to find the right value capacitors. Does anyone know where I may get the appropriate values? AES does not have these values.

: How close do the values need to be?