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

Thread Closed

model 20 radio tubes.
#1

What is the purpose of the 71A tubes. One of mine burnt out but, the radio still works. The sound is staticy(sp?)
Could this be because of the burnt tube? I did ground one of the capasitors with my finger to the ground on the chassis and the sound came clear.
But, the volume would reach a certain point then not go any higher. Any ideas?
I look forward to the answers. I'm definately puzzled. Icon_confused:
#2

I can't vouch for the static part but the Model 20 uses a pair of 71As in a push-pull configuration for the audio output. What that means is that each tube works individually on each half of the audio cycle. So yes, with one removed (or defective) the audio will not reach maximum power and is likely to sound a bit distorted.

-Bill




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Philco P45-6365 Universal Transformer Instruction Manual
Can anyone guide me to where this may be found?GRG — 03:00 PM
54C Complete Teardown/Rebuild
I don't think that I have encountered a 12Z3 before, curious how it uses one of those but includes a #43, which is a 25 ...Arran — 02:17 PM
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

[-]
Who's Online
There are currently 1947 online users. [Complete List]
» 1 Member(s) | 1946 Guest(s)
Avatar

>