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

640b e-cap values
#1

Morning guys -

Found this nice looking Philco at an antique shop last month and decided to bring it home as a birthday present to myself.   

https://philcoradio.com/library/download...l.%201.pdf

After rebuilding the bakelite blocks, checking resistors, tubes, etc, this set has hum that does not change with volume.  As I was about to swap out tubes one by one I noticed part #68, a 3 part electrolytic can on top comprising 2mfd, 2mfd and 1mfd e-caps.  I missed this and suspect it could be the hum source.  Been unable to locate these value electrolytics so far.  Are there alternatives for 1mfd and 2 mfd, 450v caps?  AES has these but only at 50v rating.  

Looking for guidance.  
Thanks very much fellas,
Paul


Attached Files Image(s)
   
#2

Good morning Paul,

Yes, that will be the source of the hum issue. Because of their low value and where they are used in the circuit, you could use non-electrolytic caps. But JustRadios and Sals Capacitors both carry 450v electrolytic caps in 1 and 2 uF sizes.
#3

Paul,

I have always been able to rebuild the multy-section electrolytics.
And, as Brad noticed, because of where they used and their values, you do not have to worry about the ripple rating and the temps, so use any reputabe mfr electrolytic caps, and they should all fit nicely inside this cap, and they have the common GND lead, so easy to do.

People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
#4

Finally. Hum is so hard to troubleshoot for me.
Thanks very much Brad and Mike.

Paul




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Need Help to ID this radio 11 tube Philco
It is a 16B tombstone.morzh — 06:13 PM
Zenith H725
David - sorry, I reread your post and finally saw THD - now the % figures make sense. Thanks for explaining. The PSU...EdHolland — 06:06 PM
Need Help to ID this radio 11 tube Philco
Hi Everyone, New member but have been reading this for awhile for tips! Vaccum tubes were before my time so bear with ...Ken D. — 06:03 PM
My Philco 37-116 Restore
Thank you MrFixR55, I appreciate your comments very much. I do not detect much hum if any so I will be staying with the ...dconant — 05:15 PM
My Philco 37-116 Restore
Hi DConant Yes, you can replace chokes with resistors.  You do stand the risk of increased hum.  the solution is to inc...MrFixr55 — 04:23 PM
Zenith H725
1.7-3.9 %, a modified Sine wave inverter is around 25%. Most generators from big box stores run 10% at a 50% load. What ...David — 04:06 PM
My Philco 37-116 Restore
I am having a heck of a time doing the alignment on the AM band. I can't seem to dial in the 1500 KC oscillator. I can h...dconant — 03:35 PM
Zenith H725
David - I think I understand but what units are you discussing (Low of 1.7, high of 3.9)? Budget constraints for Ham ...EdHolland — 01:43 PM
My Philco 37-116 Restore
You're doing great. I wish I could be more involved, but my mind is right now preoccupied with the reason I am here in ...morzh — 12:21 PM
My Philco 37-116 Restore
Hope you guys are still with me. I have moved on to the alignment. I completed the IF alignment which was pretty muc...dconant — 10:47 AM

[-]
Who's Online
There are currently 711 online users. [Complete List]
» 1 Member(s) | 710 Guest(s)
Avatar

>