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

Philco 43 - Filter Choke
#1

The filter choke in the radio is shot.  The original choke had an inductance of 100H and a resistance of 2100 ohms.  I ordered a replacement choke from Radio Daze  part 154E which is 20H at 1666 ohms

First question - looking at the Philco Book - Condensers and More it tells me if I replace the filter choke with an lower inductance I need to increase the associated filter capacitor.  Based the attached schematic I think this would be item 47.  But how much should I increase the Electrolytic condenser   right now i have a 1 8mf.

Second question - I read another post where it said you could replace the choke with a two watt 2100 ohm resistor and also increase the mf's of the condenser.  So if i used this method again would this be item 47 and what mf should I use 

.pdf Scan.pdf Size: 1 MB  Downloads: 178
#2

I wouldn't use a resistor for a rf filter.
A choke will do a much better job. For now I'd leave 47 @ 8mf see what happens depending on what it's trying to do. It's either stopping noise from other circuits from getting into the osc or signals from the osc getting out of the osc. Common practice now days would be to use a small value cap across 47 like a .01 or .005. This most of the time will block the signals from getting out. The choke and large cap stops low frequency (audio,hum, and such) from getting in.
When you get it working and it doesn't want to settle down squealing and behaving badly add some more mfd's there.

When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!

Terry
#3

The capacitor should increase proportionally to the decreasing capacitance. This said, you probably will be OK with 20H, but you do need to increase the resistance a bit so adding 400 Ohm resistor in series with the choke will keep the DC voltages the same way they were intended to be. I would increase the capacitance. I am sure it will work with 8uF, but it is easy to put in 47uF instead so why not.

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

The new choke came in added the resistor to get to the 2100 ohm changed the two condensers to 30 mfd (didn't have a 47).  Powered up the radio and the hum is gone but no sound.  So I started to check voltages. The voltage at the rectifier checked out  -  F-F was 4.65V and voltage at each plates were 349V and 347V  .  I check the voltage across the center tap and it was reading 350V on each side.  All the filament voltage at all the tubes were good.   But I have no voltage at any of the plates.  Any thoughts what i should try next???
#5

Is the spkr plugged in? What dc voltage do you have from the 80 filament to the chassis?

When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!

Terry
#6

>>powered up the radio and the hum is gone but no sound

I assume when someone says "no sound" he has the speaker plugged in, else it would not create the question "why" Icon_lol

Just trace the B+ along the way.
See where it stops.

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.
#7

Speaker was plugged in so that was easy.  Found a loose wire and start to get B voltage readings. I attached the readings up to the 1st Det (tube 44)  .  Then a new problem the wire resistor (item 57) part # 6450 started to heat up and smoke. Unplugged and called it a night.   So can you look at the attached reading a let me know what you think and what should a do with the wire resistor.  Having a hard time giving up on this the cabinet restoration came out perfect just need the radio now 

.pdf Scan_0003.pdf Size: 478.52 KB  Downloads: 172
#8

57 smoking, you have a general overload somewhere, as this is the Negative to Chassis: almost all current goes through it.
Check 1st AF for short, socket and all.

Have you checked your tubes?

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.
#9

What is 57 smoking??  Any advice where to start looking?   Could I have shorted out a tube while testing the voltage? The reason I ask is that  the smoking started when I was testing the voltage at the grid cap
#10

I did check all the tube with the tube tester they came up good, but with that yes the tube tester is 80 years old
#11

I check the 1st audio and found the K terminal was grounded to the chassis ( it was pitched under the bakelite condenser)   While tracing this I found the 13,000 ohm resistor (item 60) should be a 3 watt resistor only had a 1/2 watt  - So I will replace this when i order a 3 watt   highest i have on hand is two watts
#12

If the 1st AF K is grounded the 57 should not smoke; in fact there will be no current through it, so whatever it was that made it smoke it was not it.

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.
#13

Could have the resistor failed and is shorting to ground Only the 245 ohm side was smoking and is still reading good at 246.3
#14

The 185 and 245 ohm resistor are grounded at one end so if you ground the other it relieves any current flow thru it. So no wouldn't cause it to burn up. I would have a look around the 1st audio stage 39/44 tube as the cathode and screen voltage are developed at that string of resistors. Try removing the tube and see if you get the same results. Check for something that maybe shorting the socket at the screen or plate pins. Use an ohm meter to chassis ground. At the plate or screen should see something around 5k-10k and not 5-10 ohms.

When my pals were reading comic books
I was down in the basement in my dad's
workshop. Perusing his Sam's Photofoacts
Vol 1-50 admiring the old set and trying to
figure out what all those squiggly meant.
Circa 1966
Now I think I've got!

Terry
#15

I replaced the 3W resistor and that fix the overheating of item 57 and no more smoking.   Radio powers up fine  very low hum, slight static as i  go up and down the dial  but that is it .




Users browsing this thread: 4 Guest(s)
[-]
Recent Posts
91H Code 126 Restore
I'm pretty sure that the dotted line I circled in an earlier post signifies that it is applicable to the 226 model which...RealRider — 08:05 AM
Philco 49-1040
Hello bob, that underside looks like it is all original ! Sincerely Richardradiorich — 02:07 AM
Philco 49-1040
Oh yes, many bumblebees and loktal tubes. The cutout is for the speaker.  Here's a photo from a different set. Bob Andersen — 12:59 AM
Philco 49-1040
Bob; Looks like another "Bumble Bee" special, like my Brand Z T.O radios. Is that section they took out of ...Arran — 12:19 AM
Philco 49-1040
Hello Bob, You are like the home for lost tv's like how people bring pets home ! Sincerely Richardradiorich — 12:00 AM
Philco 49-1040
I thought I had an arrangement to restore this set for a customer but his wife said heck no.  Instead, he gave it to me....Bob Andersen — 10:29 PM
Philco 46-480 Electronic Restoration
I kept working on reassembly this week. I wasn’t able to solder for a few days while it was too cold (single digit low t...jrblasde — 09:27 PM
Atwater-Kent 84, restoration.
Well, powering it up would be too good to be true, and I had that feeling. Before I did, I decided to check the coils...morzh — 06:02 PM
An attempt to remove the Field Coil from a G speaker
Thanks Chas, sure will give it a look!morzh — 03:39 PM
An attempt to remove the Field Coil from a G speaker
Mike, Lookup  murrayatuptown on ARF. Seems he has a dilemma with surplus field coils. Could get lucky and have what y...Chas — 01:26 PM

[-]
Who's Online
There are currently 2861 online users. [Complete List]
» 1 Member(s) | 2860 Guest(s)
Avatar

>