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

Re: Model 20 Modification
#1

I am in the process of restoring a Model 20. This radio works, but has an odd modification which am trying to un-modify. The radio as built should have had a 27 af tube feeding two 71A's in a push-pull configuration, through an interstage transformer. This was modified in the following ways: the 27 was replaced by a 47 and feeds the speaker directly. The 71A's were removed, as was the interstage transformer. I am wondering if anyone has seen this type of mod? Looks like it was done some time ago. The radio does function this way. Unfortunately the tube sockets for the 71A's have been removed and the tubes physically replaced with metal can caps. I haven't traced all the wiring yet, but I suppose these are being used to bypass the original filter caps. The speaker was also replaced - with an old Jensen field coil speaker. Has anyone else seen such a modification?
Thanks
#2

Certainly NOT a factory mod. Your radio has lost a stage of audio amplification by using a 47 in place of the 27 audio amp and not using the push pull 71As at all.

You could always convert it back by adding two 4 pin tube sockets where the hole covers are now at...as well as an interstage transformer, push-pull output transformer, 71A tubes, a 27 tube, undoing the modified wiring, etc.

--
Ron Ramirez
Ferdinand IN




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Philco 91 Restore Code ??
No, that cannot be the 47. The 47 is a regular backelite block cap. Look at the chassis picture, it is shown there. Rig...morzh — 01:45 PM
Philco 91 Restore Code ??
I have changed the title of this thread from Philco 91 Schematic. I have gone through most of the cap replacements. I...dconant — 01:26 PM
462ron
Here is an online transistor substitution site… Ron462ron — 08:44 AM
1930s Stewart-Warner Tombstone Radio need help identifying model number
One way to repair a broken wire on a coil is to take a copper strand out of some 18 gauge electrical cord, make a &quo...captainclock1988 — 12:55 AM
B&K 1077B no video
Hello Tim, I once had a Jcpenny 13inch tv /monitor built by NEC come into my repairshop it would start acting up at tim...radiorich — 10:59 PM
Restoring Philco 96
Mike; The last time I took a potted condenser can apart, and it was maybe 1/4 the size of the one in the model 96, I ...Arran — 10:56 PM
Compatible crts
Bob Andersen — 08:58 PM
1930s Stewart-Warner Tombstone Radio need help identifying model number
One way to repair a broken wire on a coil is to take a copper strand out of some 18 gauge electrical cord, make a "...Arran — 08:41 PM
Restoring Philco 96
Have just aligned it. Surprisingly, it was not that much off at all. Barely. Aligning TRF sets is pure pleasue, as ther...morzh — 07:52 PM
6TPZ and 5TPO Radio Help
1 - 0v - correct 2 - 0v - correct 3 - 0v - --------------------- both 3 and 4 should be the same. Check L2 for being ope...morzh — 05:15 PM

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

>