My next radio project is a Philco 511. Thanks to Ron's wonderful website I was able to date this radio to 1928. It's a Spanish Brown Case, sadly no speaker.
I plan on using a pair of Circa 1915 Baldwin Type C headphones as there is a jack on the escutcheon to accept headphones. Will a pair of Type C Baldwin headphones work for this receiver??? How would I figure out if these headphones would work.
I already have the parts for restoration, but I am stumped on the main Filter block ( Part #3108 ) I am trying to discover the values within. I was not able to find this part number on the Philco Repair Bench Site. Can anybody help me?
Thanks
Jon
(This post was last modified: 08-31-2015, 06:07 PM by Philco281989.)
P.S Oops, I didn't notice that Ron already posted that link, those schematic pages are very useful in identifying parts in the early sets. For some reason Philco, like Atwater Kent, thought that actually posting part values on the schematic would violate some sort of trade secret.
(This post was last modified: 09-01-2015, 01:04 AM by Arran.)
Thank you both for the responses and the schematic. My Filter questions are answered. If the front input was for a Phonograph Connection. Could I use the speaker connections (Being two separate posts) as inputs for a set of headphones? Or is this set meant only for a speaker?
Thanks
Jon
"A Minute of Care is Worth an Hour of Repair" circa 1930.
(09-01-2015, 10:45 AM)Philco281989 Wrote: Thank you both for the responses and the schematic. My Filter questions are answered. If the front input was for a Phonograph Connection. Could I use the speaker connections (Being two separate posts) as inputs for a set of headphones? Or is this set meant only for a speaker?
Thanks
Jon
Yes you can use it for phones or a hi impedance spkr.
(09-01-2015, 10:45 AM)Philco281989 Wrote: Thank you both for the responses and the schematic. My Filter questions are answered. If the front input was for a Phonograph Connection. Could I use the speaker connections (Being two separate posts) as inputs for a set of headphones? Or is this set meant only for a speaker?
Thanks
Jon
Yes you can use it for phones or a hi impedance spkr.
Terry
Cool, thanks Terry. I just might try those Baldwin headphones when it comes time to power up this set. I might also try a PM speaker with an audio transformer. The set will not sound as loud, but this set up could work when it comes time for an alignment, right?
Jon
"A Minute of Care is Worth an Hour of Repair" circa 1930.
I have been digging deeper into the set. The filament by-pass condenser (2 sections at .5 mfd) has been replaced as you can see in the picture below. I just disconnected the old block from the circuit and replaced it with two .47 MFD caps with respect to a grounding lug coming off the tuning condenser. I have been looking at the by-pass condensers (.1 mfd with Plate Resistance winding #3114-A). They look a little tedious. I don't really know how to tackle them just yet. From my understanding the .1 MFD is within the tar and the wire wound resistor sits on top. Are these both soldered together at each lug on each end?? If so I could just disconnect the old cap and still use the wire wound resistance.
WOULD IT BE OK TO USE CERAMIC DISK CAPACITORS WITHIN THE BY-PASS SECTIONS (PART #3114-A)?????????
I am deciding on what to do with the filter block. Any ideas? I will not be re-stuffing capacitors on this set. There is a bit of room per the last picture, where a stamp resides. Anyone know anything about this chassis stamp? I was thinking of putting the new caps in this area. I don't know just yet.
Thanks
Jon
"A Minute of Care is Worth an Hour of Repair" circa 1930.
I discovered via the schematic and looking at the by-pass condenser's with their plate winding resistors that there are three lugs. The first lug that connects to the coil houses one side of the .1 MFD cap and one side of the wire wound resistor. The second lug connects only the wire wound resistor. The third lug connects only one side of the capacitor to chassis ground. With this idea in mind I was able to replace each cap with a .1 MFD ceramic capacitor rated to 500V. All wire wound resistor tested within 10 percent tolerance, success! I highly doubt the peak voltage of this set is higher than 400V. I just hope since these ceramic caps are on the DC side of the circuit that the capacitance is not lowered too much as a result of the DC current flowing through them.
Via the pictures below, this is how I replaced the condenser sections within each part.
Jon
"A Minute of Care is Worth an Hour of Repair" circa 1930.
Sorry I didn't see your post earlier. I cheated on my 87 it has the same type of cap/res setup. I just cut the ground wire off of the cap and wired a little yellow guy under it. All of mine where almost a dead short.
(09-05-2015, 01:30 PM)Radioroslyn Wrote: Sorry I didn't see your post earlier. I cheated on my 87 it has the same type of cap/res setup. I just cut the ground wire off of the cap and wired a little yellow guy under it. All of mine where almost a dead short.
Terry
One of the questions I keep finding myself asking is whether ceramic's are an ok option for the by-pass/26 plate section. Someone mentioned that the DC going through these caps will lower their capacitance. I would imagine the peak voltage would not be higher than 350V or so. These caps, while rated at .1 MFD, are reading out of the circuit as .080. Close enough. But what happens when DC is applied to them, would they go lower than .080 disrupting the capacitance that is suppose to be within this section of the circuit? The caps are rated to 500V. Maybe I am being a little over critical?
Jon
"A Minute of Care is Worth an Hour of Repair" circa 1930.
Jon, a little clarification about caps in general. DC current does not pass through a capacitor unless it is bad (leaky). A capacitor will have a DC voltage applied across it, but aside from the initial current needed to charge the cap, no further DC current will flow.
In the case of high capacitance ceramic caps, the effective capacitance is a function of both voltage applied and temperature, The capacitance may change a few percent as the applied voltage is increased, but it really won't make much of a difference when used as a bypass.
What sort of caps are you planning to use for the power supply filters? Mylar or polypropylene film would be recommended, as modern small capacitance electrolytics won't hold up in this application.
(09-05-2015, 07:49 PM)Mondial Wrote: Jon, a little clarification about caps in general. DC current does not pass through a capacitor unless it is bad (leaky). A capacitor will have a DC voltage applied across it, but aside from the initial current needed to charge the cap, no further DC current will flow.
In the case of high capacitance ceramic caps, the effective capacitance is a function of both voltage applied and temperature, The capacitance may change a few percent as the applied voltage is increased, but it really won't make much of a difference when used as a bypass.
What sort of caps are you planning to use for the power supply filters? Mylar or polypropylene film would be recommended, as modern small capacitance electrolytics won't hold up in this application.
Thank you very much for the clarification on this situation. I have decided to leave the ceramics in place as it will not make much of a difference.
You bring up a very good question on the main filter block. I was planning on using electrolytic's rated to 600V due to the limited space under the chassis. Would this be a bad idea, and for my learning benefit (Since I am still a novice) why should I not use electrolytic's for this set?
Thanks
Jon
"A Minute of Care is Worth an Hour of Repair" circa 1930.
When it comes to these older sets with small value caps I prefer mylars. My 87 I put Ecaps in it and after 6months of uses (a few hours daily) they shorted. Used two 4.7mfd @ 450v in series. It's out in the shed now.
Yes, as Terry said electrolytics will not hold up long in this application.
Small value electrolytics are not rated for the ripple current they will be subjected to in a tube power supply filter. The lower the capacitance, the lower is their ripple current rating, and a modern 2 uF electrolytic was not designed to be an input filter in a vintage tube power supply. They will overheat and eventually fail.
Back when the 511 was designed, capacitors were expensive and so they used the smallest capacitance paper caps possible. These caps could however handle the ripple with no problem.
Today, the best option for replacement is a film type cap. They are designed to handle such service and will basically last forever. These are the type I use and have been very happy with their performance.
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