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 Model 20 volume control operation
#4

The volume control should be a dual pot. One section, as Keith described pads down the antenna input and decreases the signal level. The second section adjusts the bias on the RF amplifier tubes and sets the level of signal amplification.

It sounds as if the second pot section on your radio is not working properly. This pot is connected as a voltage divider, connected as part of the large wirewound resistor on the side of the chassis. If you connect a voltmeter to the sliding contact of this pot section, you should see the voltage change by several volts as the pot is rotated. If you see no change, then either the pot is bad or there is an open section in the wirewound bias resistor.

If working properly you should have good control of volume level, even on a fairly strong signal.


Messages In This Thread
RE: Philco Model 20 volume control operation - by Mondial - 10-17-2013, 08:12 PM



Users browsing this thread: 3 Guest(s)
[-]
Recent Posts
6TPZ and 5TPO Radio Help
Quick progress report: X7 is broken. Only one leg soldered, the other missing and the diode is cracked. I've replaced...R3Sons — 05:05 PM
6TPZ and 5TPO Radio Help
Oh...and you have electrolytic caps there. All need to go and be replaced.morzh — 04:36 PM
6TPZ and 5TPO Radio Help
Thanks, will do.R3Sons — 01:25 PM
1930s Stewart-Warner Tombstone Radio need help identifying model number
UPDATE: I was able to pick up a signal generator on the cheap (amazingly enough) on feebay and I did an IF alignment fol...captainclock1988 — 09:53 AM
Philco 91 Schematic
Hi Rod, The resistor connects to pin 4 and the ungrounded side of block 9. From pin 9 of the RF tube to one side of ...dconant — 09:34 AM
Just got a 49-1613 need to know...everything!
I just found your post. I have this exact same model, and have had it since 1985 when I was 15 years old! I performed a ...MuzzcoVW — 09:11 AM
B&K 1077B no video
Hello Tim, I would if it's a leaky Capacitor So are all 3 of those B- voltages low then ? Sincerely Richardradiorich — 01:55 AM
B&K 1077B no video
I found a schematic and think I have the problem traced down to the minus power supply. I have very low voltages that go...TV MAN — 12:41 AM
RCA 15X
I'd try replacing the bulb first and if that doesn't do it, then change the 35Z5 and see if the problem goes away.NostalgiaRadioTime — 12:28 AM
B&K 1077B no video
Hello Tim, I have that exact unit in my shop too plus a Sencore unit there are times I like one or other !!. Sincerely...radiorich — 11:07 PM

[-]
Who's Online
There are currently 10438 online users. [Complete List]
» 4 Member(s) | 10434 Guest(s)
AvatarAvatarAvatarAvatar

>