Hello Everyone,
Well it happen after around 20 years of faithly listening to my Philco 601b that I restored in about 2004-2005 ,
One Sprague Atom electrolytics finally went bad .
This time I have Decided to go with using Film Capacitors and chose these Panasonic capacitors either the 3.9ufd or 4.7ufd at 630volts I can use . here is the link to mouser showing the capacitors .
Since this set uses two 8ufd electrolytics and one 16ufd electrolytic capacitor I will use two 3.9 ufd or 4.7ufd in parallel to come up with 8ufd's and four in parallel for the 16ufd .
if I use to 4.7ufd will 9.4ufd cause any issues ? far as I figure I am good .
read this Following information and where it talks about a Fuse will that cause any issue ?
Quote:Designed for DC applications that don't require sisnificant amount of pulse current .The built- in fuse function for use for DC linkage and have low hum .
One thing that glad about is I stuffed the original cans so they are very easy to open up and replace the capacitors the other Idea I using crossover coupling capacitors like Solen or Audyn brand .
So if you had your choose which route would you go ?
Sincerely Richard
First of, 630ufd - did you mean "Volts"?
I habitually use 11uF in place of 8uF. With no ill effects. I serialize two 22uF Panasonic electrolytics to achbieve this. Each of them is 450V, so it becomes 900V WV cap.
Speaking of. If you used Hi-ripple Panasonics, and not Atoms your electrolytic cap would likely outlive you.
But fim is good.
PS. todays caps tolerance is 20% meaning when you think you have 10uF, you might have 8uF or 12uF. Which means any half-decently made schematic should allow for a standard tolerance. Which means, your 9.4uF should not cause issues.
Hello morzh ,
yes I meant 630 volts and yes I know those Panasonic film capacitors will most likely out live the rest of the set !
I used a lot of those Sprague Atom capacitors thou out the years back in the 80s and 90s at my Repairshop I used them more then any other next to Nichicon PC mount .
Sincerely Richard
If memory serves me correctly, tolerance for old school 'lytics were something like +80 / -20%, so the cap could be 20% low or almost double the rated capacity.
I don't know why capacity of filters was so low back in the day. Go forward a few years and instead of 8 or 16uF caps, you see more like 20, 33, 47uF and still saw a field coil doubling as a choke. Did cap tech improve, causing manufacturers to raise capacity of what was installed?
Granted, if increasing capacity, this may raise B+ but may improve hum. However, if it works well with the originals, then leaving well enough alone would be a good idea.
80 / 5Y3 are rated for up to 40uF cap from cathode to center tap, but that may be for later versions; that spec is not in the RC10 (1932?) version of the RCA Receiving Tube Manual but is in the RC14 (1940) version of the manual. This may be because by then, the 5Y3 had come out and the 80 and 5Y3 have the same specs but with the 5Y3s improved filament
Large value capacitors were expensive, and even after electrolytics came about the values seem to have been limited. It's not unusual to see a mid 1930s radio with a 4 uf input cap, and an 8 or 10 uf on the output. I've sometimes wondered if the small values they had available were the reason they would have another filter cap added in the B+ to the front end of the radio? The reason they continued using field coil speakers may have been the lack of decent permanent magnets, or in the case of the pre war sets, a lack of materials to manufacture aluminum-nickel-cobalt P.M magnets, or just that it was the convention so long that they had a large inventory of field coil speakers available. I recently picked up a post war Stromberg and it has a P.M dynamic, with a pi filter in the power supply with a power resistor in place of a choke (not really a good idea given that the set had a pair of 6L6Gs in push pull) but have seen other makes and models with the field coil speakers. I think that Stromberg manufactured their own speakers, at least for their upper end models, so they didn't have to worry about parts shortages, whereas Electrohome did not make their own so they used field coil speakers made elsewhere.
Regards
Arran
Hello Arran
Yes I believe it is like in the hardrive Business look at how small hard drives were in the early days and their price .
Mr fixr, "Did cap tech improve, causing manufacturers to raise capacity of what was installed?"
This also opens up another question what Arran was talking about the Speakers and better magnets .
As you know these sets were being made at price break and with better capacitors and speakers they could do away with the field coil .
Sincerely Richard
Richard, I’m thinking capacitor technology in the early days was limited as you find single digit capacitors that were huge compared to today. I am amazed at my Majestic 50 where there are only a couple of 1mfd caps, a 2mfd right off the rectifier and a 3mfd and yet even with a 10” speaker I need to put my ear right up to the speaker to hear the faintest hum with the volume all the way down. But then this set has a filter choke and also uses the field coil for filtering. Even my Philco 37-116 only uses a few 8mfd caps but has 2 filter chokes and a field coil and the amount of hum I hear from its 15” speaker is negligible. Those early sets really depended on the chokes for the bulk of the filtering!
Ron
Hello Guys,
One thing I was reading was the max capacitance for a 80 rectifier is 20ufd
so if I put four of those 4.7ufd film in parrallel it is roughly 18.8 ufd is that going to push that tube to hard ?
See the other set that I am going to start restoration of is my Philco 38-10t it uses a 5y4
Sincerely Richard
+1, 462 Ron.
I am not sure when AlNiCo was invented, but I think it was likely perfected for WWII. The only pre-WWII PM dynamic speakers that I have ever run into were in battery powered sets and in earlier sets like my 1935 / 36 RCA 5BT and 6BT and Coronado 650 Farm Sets, these magnets were pretty big. I have twin 1933 4 tube lunchboxes, an RCA R-17M and GE BX (Actually the same radio, RCA Made GE and Westinghouse radios from 1930 - 1935. GE and Westinghouse made RCA Radios from 1922 till 1930 till RCA bought Victor Talking Machine who had just starting manufacturing radios), and for a little 5" speaker, the magnet is quite large. The horseshoe magnet in my Radiola 100A magnetic speaker is similar to the type used in the generator of the old hand crank telephones prior to central station phone systems.
Alnico was "invented" in Japan in the 1930s.Alnico speakers started to sow up in the 1950s. Jensen Alnico speakers are prized by many audiophiles, they can be quite expensive due to the Cobalt. Paul
Hello Paul,
Yes I have some Jensen woofers from the 1950s just waiting for a Project .
I got some plans to build a pair of speakers .
Sincerely Richard