Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12, 2025) x

Thread Closed

Philco 20A - Electronic Restoration Questions
#15

When this radio was made, large value capacitors were physically large and expensive. Radio manufactures tried to use the lowest value capacitors they could get by with. One of the tricks Philco used was to use a specific value capacitor in parallel with a choke to create a tuned circuit to filter the hum. The problem with that is, if the value of the capacitor is either too high or too low, it can actually increase the hum. Some may disagree, but I think it best to omit this capacitor and increase the value of the second filter to compensate. It is not a good idea to increase of the first filter because this will increase the B+ voltage.

Steve

M R Radios   C M Tubes


Messages In This Thread
RE: Philco 20A - Old cap can caps - by morzh - 08-09-2017, 08:03 PM
Capacitors for Philco Model 20 - by MrGrnEgz - 08-09-2017, 11:12 PM
RE: Capacitors for Philco Model 20 - by MrGrnEgz - 08-10-2017, 09:50 AM
RE: Capacitors for Philco Model 20 - by MrGrnEgz - 08-10-2017, 02:46 PM
RE: Capacitors for Philco Model 20 - by MrGrnEgz - 08-10-2017, 03:27 PM
RE: Capacitors for Philco Model 20 - by Steve Davis - 08-10-2017, 09:56 PM
RE: Capacitors for Philco Model 20 - by MrGrnEgz - 08-11-2017, 05:26 AM
Model 20A Frequency Indicator - by MrGrnEgz - 08-11-2017, 05:38 AM
Model 20A Power Cord - by MrGrnEgz - 08-12-2017, 01:18 PM
RE: Model 20A Power Cord - by Radioroslyn - 08-12-2017, 01:28 PM
Model 20A Speaker Cone Repair - by MrGrnEgz - 08-13-2017, 09:41 PM
AUX audio input for model 20A - by MrGrnEgz - 08-13-2017, 10:54 PM
RE: Model 20A Speaker Cone Repair - by MrGrnEgz - 08-14-2017, 08:50 AM
RE: Model 20A Speaker Cone Repair - by morzh - 08-14-2017, 04:48 PM



Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
HiFi (Chifi) tube amp build - but my own design.
It's the other forum. I'm also in DIY, but mostly read there. Honestly, I kinda jumped into this without much thought to...TV MAN — 10:43 AM
Philco 71 Code 125
Hello,  I am in need of a schematic for this radio. Mine has the three separate circular tube shields and a shadow me...dconant — 08:06 AM
Stromberg Carlson 1500 Squeal
And life just keeps getting more complicated.dconant — 07:57 AM
54C Complete Teardown/Rebuild
Hello Roy, here is this one sincerely Richardradiorich — 12:45 AM
54C Complete Teardown/Rebuild
Richard, Had grabbed it already but thank you just the same.  I find myself wanting to find some way to block out the...glyphmon — 12:03 AM
54C Complete Teardown/Rebuild
Hello roy, here is a link to the schematic . Sincerely Richardradiorich — 11:54 PM
54C Complete Teardown/Rebuild
Richard, The Silvertone 2014 also is a transformerless set, so I am incorporating a 1:1 600 ohm audio isolation transfo...glyphmon — 11:37 PM
Preliminary work on wife's Silvertone 2014
Did an alignment today which was interesting.  IF alignment went great, almost all was already spot-on.  Adjusting on th...glyphmon — 11:35 PM
54C Complete Teardown/Rebuild
The main problem with adding a Bluetooth input is that this set lacks a traditional power transformer to isolate it from...radiorich — 11:19 PM
54C Cabinet Refinish
I started stripping this cabinet before it got super chilly out because I knew I wasn't going to be able to work on ...glyphmon — 11:18 PM

[-]
Who's Online
There are currently no members online.

>