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

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

Philco model #20
#5

Hi Rick,

Here is a link to the schematic for the Model 20. It is found in our Philco Library under Documents under early schematics.
https://philcoradio.com/library/index.ph...chematics/


Yes, definitely cut the wire and add a resistor of 970 Ohm +/- 20%. A 1K 5W or preferably 10W resistor will do fine. Having that resistor section shorted raises the voltage across the rest of the divider and puts undue strain on the other resistors in the voltage divider- the subsections of this taped resistor, and definitely the volume pot which is part of the divider. The volume control has 2 sections. One section, connected to points e and F adjust volume by varying the cathode bias. The other section of the volume pot controls the strength of the signal entering the first RF amp. This set has no AVC. Too strong a signal will saturate the 1st and 2nd RF Amp and cut off sound. This is not evidence of an issue with the set.

The filter caps in this set are not electrolytics. they are paper and foil. However, they should be replaced, along with all the other caps. Removing the caps form the can is not very easy, but is doable.

The other caps and some resistors are enclosed in Bakelite "blocks" sealed with tar. Below is a link to an excellent article by Phorum member "Morzh" on how to hollow out the blocks and replace the parts inside without having to desolder the blocks from the set:
https://philcoradio.com/library/index.ph...soldering/

Also attached is a great article on issues with the audio "interstage" transformer, how to "bridge" an interstage transformer with an open primary (a common problem) and how to rewire a good transformer to capacitively couple the primary to the 1st AF stage, removing DC from the primary, extending the life of the transformer and greatly improving fidelity:
https://philcoradio.com/library/index.ph...nsformers/

This is a "TRF" (Tuned Radio Frequency) receiver, which performs rather well. This was a seminal set, as it was introduced in the throes of the Great Depression. This set ushered in the "Cathedral" style, and sold for around $50.00, providing great value for the price.

I am about to crash and burn for the night.

Hope this helps

"Do Justly, love Mercy and walk humbly with your God"- Micah 6:8
"Let us begin to do good"- St. Francis

Best Regards, 

MrFixr55


Messages In This Thread
Philco model #20 - by onlyrick - 03-17-2025, 08:44 PM
RE: Philco model #20 - by morzh - 03-17-2025, 09:15 PM
RE: Philco model #20 - by morzh - 03-17-2025, 09:17 PM
RE: Philco model #20 - by morzh - 03-17-2025, 09:17 PM
RE: Philco model #20 - by MrFixr55 - 03-17-2025, 09:48 PM
RE: Philco model #20 - by onlyrick - 03-17-2025, 10:46 PM
RE: Philco model #20 - by onlyrick - 03-18-2025, 10:22 PM
RE: Philco model #20 - by morzh - 03-18-2025, 11:01 PM
RE: Philco model #20 - by morzh - 03-18-2025, 11:05 PM
RE: Philco model #20 - by Steve Davis - 03-19-2025, 12:17 AM
RE: Philco model #20 - by morzh - 03-19-2025, 12:26 PM
RE: Philco model #20 - by onlyrick - 03-19-2025, 10:27 PM
RE: Philco model #20 - by onlyrick - 03-21-2025, 10:00 AM
RE: Philco model #20 - by onlyrick - 03-23-2025, 05:01 PM
RE: Philco model #20 - by MrFixr55 - 03-23-2025, 08:35 PM
RE: Philco model #20 - by onlyrick - 03-23-2025, 09:53 PM
RE: Philco model #20 - by Steve Davis - 03-24-2025, 02:02 PM
RE: Philco model #20 - by morzh - 03-24-2025, 02:41 PM
RE: Philco model #20 - by onlyrick - 03-24-2025, 03:34 PM
RE: Philco model #20 - by morzh - 03-24-2025, 06:19 PM
RE: Philco model #20 - by onlyrick - 03-26-2025, 09:37 PM
RE: Philco model #20 - by morzh - 03-27-2025, 12:40 AM
RE: Philco model #20 - by onlyrick - 03-27-2025, 11:15 AM
RE: Philco model #20 - by radiorich - 03-27-2025, 12:15 PM
RE: Philco model #20 - by morzh - 03-27-2025, 01:41 PM
RE: Philco model #20 - by onlyrick - 03-27-2025, 03:55 PM
RE: Philco model #20 - by morzh - 03-27-2025, 06:03 PM
RE: Philco model #20 - by onlyrick - 03-27-2025, 09:23 PM
RE: Philco model #20 - by morzh - 03-27-2025, 11:17 PM
RE: Philco model #20 - by onlyrick - 04-04-2025, 09:34 PM
RE: Philco model #20 - by MrFixr55 - 04-04-2025, 10:30 PM
RE: Philco model #20 - by MrFixr55 - 04-05-2025, 08:22 AM
RE: Philco model #20 - by RodB - 04-05-2025, 09:46 AM
RE: Philco model #20 - by onlyrick - 04-05-2025, 02:24 PM



Users browsing this thread:
[-]
Recent Posts
5U4 vs 5Z4 tubes
The pinout is the same but the 5U4 has a 3 amp filament, verses 2 amps or less on the 5Z4. I think that the pinout of a ...Arran — 12:04 AM
Philco 42-345 Restoration/Repair
By the way. osanders0311 Take a look here: Dial cord stringing Guides May be here you can fount correct string settin...Vlad95 — 11:15 PM
5U4 vs 5Z4 tubes
5U4 and 5Z4 almost identical. I think nothing happened if you left 5U4 instedad 5Z4 long time. Just heater current 5U4 ...Vlad95 — 11:02 PM
Philco 42-345 Restoration/Repair
Hello Vlad95 , Very Funny ! Sincerely Richardradiorich — 11:01 PM
Philco 42-345 Restoration/Repair
RodB You are European yourself   :evil: I'm Canadian for the last 30 years  :snowman: But not Yankee  :lol: Vlad95 — 10:49 PM
Philco 42-345 Restoration/Repair
The band switch selects different oscillator coils for the band selected. I would look for a bad connection in the switc...RodB — 10:31 PM
Philco 42-345 Restoration/Repair
Hang in there...PaulPaul Philco322 — 09:30 PM
Philco 42-345 Restoration/Repair
The thrill is gone again, thought I was close to being done with it. Well Friday it was receiving broadcast, Saturday mo...osanders0311 — 07:47 PM
Help with Supreme 599
Iam getting closer to fixing it. I bumped Up the tranny voltage to get 5v on the 80 tube. I gan get the needle to move ...daveone23 — 03:41 PM
Philco 42-345 Restoration/Repair
Hello RodB, Checking my previous post I realized you're the one with the 42-340. I replaced the string for the tuning...osanders0311 — 03:12 PM

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

>