Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12) x

Thread Closed
Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

0.00011 mf caps in bakelite blocks
#1

I'm working on my model 116.  What is the concensus?  Are these 0.00011 mf capacitors replaced during restoration?  On one hand, that value suggests they're mica, which is usually left alone.  But on the other hand, why would these capacitors be potted in tar?  This suggests they are subject to degradation over time.
#2

Inside backelites these are not mica.
Even if they are safe they have likely drifted, they are typically replaced.
#3

I've always used dipped mica 110pF caps here; they are cheap and perfectly suitable for the purpose. I buy at least 20 at a time. These are the caps that look like dark caramel candy.

Pete AI2V
#4

From all of the Philcos that have crossed my bench...and they number in the hundreds, I never bothered to count them...out of those that have 110 pF caps in bakelite block shells, the majority were small paper caps. I have encountered a few that had mica caps encapsulated in the tar, though...but as I said, the majority were paper.

As Pete (AI2V) said, dipped micas are excellent replacements for these. And, yes, I replace them as a matter of course in the Philco sets that use them.

--
Ron Ramirez
Ferdinand IN
#5

[Image: http://www.talonix.com/images/caps4/39pfDSM.jpg]

Looks like this.  Some are larger or smaller, depending 
on the capacitance and working voltage.
#6

I just pulled 4 of those out of bakelite block shells last week and all 4 were paper. I used the dipped micas like in Chuck's photo.
#7

Another question, about the voltage rating on these caps; what were they originally? I would assume 500V micas would be fine?
#8

Yes 500 volt micas will be OK.
#9

Can you double check that? The bakelite block I'm restoring is pn 8035-DG. Philco Service Bulletin No. 289 suggests these capacitors have a working voltage of 1200v.
#10

The maximum voltage these are going to see in the 2nd Detector circuit will be so low as to not be consequential, really.

You can use 1200 VDC caps if you wish. H**l, you can use 12,000 volt caps if you want to. But Codefox is correct, 500 WVDC caps are fine. Even 300 WVDC micas are fine. I use the 500 WVDC micas all of the time to replace these and I haven't had a single failure yet...and I do not expect to since they will only be exposed to somewhere between 0 and 10 volts in this circuit.

--
Ron Ramirez
Ferdinand IN
#11

(12-09-2014, 05:19 PM)Kestas Wrote:  I'm working on my model 116.  What is the concensus?  Are these 0.00011 mf capacitors replaced during restoration?  On one hand, that value suggests they're mica, which is usually left alone.  But on the other hand, why would these capacitors be potted in tar?  This suggests they are subject to degradation over time.

Hi guys, I have run into the same bakelite block in my 38-2 as Kestas.Just a question would 0.0002 @ 630V be to much to use in place of the 0.00011? I have these on hand,but if I have to I will order the correct replacements.
Thanks 
#12

Quote:Just a question would 0.0002 @ 630V be to much to use in place of the 0.00011?
You should stay within a 10 to 20 percent tolerance.
#13

Just ordered up some 110pf caps so i should be good until I tackle THE BEAST my 38-116. After the 38-2, i
would hope things will be easier,still will be a challenge I know. Icon_thumbup but I'm up for it.
#14

Oh...it's just a bunch of wires, glass an metal....nothing a man with a scredriver couldn't take on.
#15

FIRE UP that soldering iron an lemme at it.Wait, I still have to finish the 38-2. Icon_biggrin




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Need to purchase some accessories for restoration of my Old Philco Radio
Here is a list of resources found in our online library that you might find useful. Mike's Gobs of Knobs email addres...klondike98 — 01:46 PM
First Radio restoration
Hi Tubeman, Welcome to the Philco Phorum.  Phamily Phriendly Pfun with Phine Pholks Phull of Philco Phacts. (See a p...MrFixr55 — 12:33 PM
First Radio restoration
You could post in the WANTED ADs section here on the Phorum and see if anyone has an RF generator that they want to sell...klondike98 — 11:55 AM
Zenith H725
Good ideas, thank you Arrange and Rich. I have the adhesive aluminum foil already and can try that immediately. More ...EdHolland — 10:18 AM
Graphics for majestic 1050 dial glass.
Murf; I found this thread on the ARF, the first photo has a pretty good view of the dial glass. Regards ArranArran — 01:12 AM
Zenith H725
hello Ed, how about that speacial tape used for ducting it's like foil or how about thin piece of aluminum roof flash...radiorich — 12:19 AM
Zenith H725
Ed; One material that I have seen, but never tried for this was material for making exhaust gaskets, it's similar to ...Arran — 11:42 PM
Zenith H725
I just remembered, I have some hi temp silicone rubber material which could do the trick. Or a piece of FR4 laminate. Th...EdHolland — 08:39 PM
Zenith H725
The PSU filter cap arrived today (thank you USPS!) so I will work on that later. Meanwhile, I have the dial, speaker...EdHolland — 06:42 PM
Philco 610B oscillator wiring
Thanks Terry. After checking my notes I think I recorded about -10v at the 6A7 G4/control grid. The screen grid (G3 &...Tubester — 05:59 PM

[-]
Who's Online
There are currently 1539 online users. [Complete List]
» 3 Member(s) | 1536 Guest(s)
AvatarAvatarAvatar

>