Adams-Morgan Paragon Type Two

© Copyright Alexander D. Schapira, 2011-2014, All rights reserved

With thanks to all who provided suggestions, I am providing this account of how I repaired an
Adams-Morgan Paragon Type Two receiver.
I hope this will be of some interest to other Adams-Morgan afficionados.

I acquired this Adams-Morgan Paragon Type Two receiver because in the 1920's the Adams-Morgan company was located in Montclair, New Jersey, where I live. I thought it would be neat to have a hometown radio, even though this one was not in very good condition.

The set was extremely dirty, so my first task was a cleanup.

The amplifier tube socket was cracked, and virtually every screw terminal was loose and every soldered joint crumbled apart when touched.

There is remarkedly little information on this set available anywhere. Steve Rosenfeld amazingly dug up some hand drawn schematics, sans component values. Here are the values of the components in my set: Al Klase kindly provided me with a copy of an article about the Adams-Morgan Company.

My Type Two came with a Wizard X-201-A in the detector socket and a Cunningham CX-300-A in the amp socket. This does not make sense, as the 201-A is a better amplifier than detector, and the 300-A is described as a detector. (The 300-A turned out to be bad.) Also, the interstage audio transformer was clearly not an original Adams-Morgan unit.

When I finally got to work on it, as I expected, the secondary of the interstage transformer appeared open, as was the glass tube grid-leak resistor.

I rebuilt the 4 meg grid-leak resistor by replacing the carbon-paper element inside the glass tube with a modern discrete resistor.

The grid-leak resistor
Opened up

There are a number of differences between my set and various pictures of the Type Two floating around here. The two biggest differences are
  1. My set has six binding posts out the back of the cabinet connected inside to various points, whereas in the on-line pictures there are no binding posts, but rather an internal row of six terminals on a bakelite strip.
  2. My set has the detector tube near the back rear corner of the set and the grid leak is between it and the tuning capacitor, whereas in the pictures, the grid-leak is in the corner and the detector tube is to its side.

The coil, tuning capacitor, rheostat, grid leak assembly, and front panel all look like the ones in the on-line pictures. Amazingly, the grid-leak capacitor, an early Dubilier unit, was still within spec!

The grid-leak capacitor

There was probably a lot variation in the manufacture of these sets near the end of their production, but it is also possible that the set was modified when the original interstage audio transformer was replaced. To check this, I removed the detector tube socket and underneath found screw holes that match the grid-leak assembly. So its entirely possible that the detector tube and grid-leak were moved (interchanged) to make room for the replacement transformer. I did not remove the transformer to see if there are holes underneath it for a tube socket. There is no sign of a bakelite bracket for an internal terminal strip. I decided to rebuild the set configured as I found it.

I found that almost every soldered connection virtually fell apart when barely touched. Also, every screwed terminal was loose and corroded. It took a while to repair all the bad wiring and connections.

I repaired the cracked tube socket, cleaned the hardware, and repainted the engravings on the knobs and front panel.

Cleaned up hardware
Repainted engravings

I also replaced the cracked center knob of the main tuning dial with one on hand, although it is slightly larger than the original.

Here is the chassis cleaned and repaired.

ITS ALIVE!!

After I rebuilt the grid-leak resistor, repaired all of the bad and corroded connections, fixed loose terminals on the tube sockets, and replaced a bad tube, I got it to work with three outboard power supplies. I used about 35V B+ on the detector, 70V B+ on the amplifier, and 5V for the filaments. I hooked up an outboard audio output transformer and speaker. The Type Two receives the standard AM band even with a short antenna and drives an 8" speaker through a small audio output transformer to a reasonable volume.

The inter-stage transformer secondary originally appeared open because the inner set of nuts on its terminals were loose and corroded, apparently not making contact with the winding. Once these were cleaned and tightened, the secondary showed 7.5 K. So, I don't need to replace the transformer for functionality, but I may do so for originality's sake.

The circuit is a regenerative detector in which one varies the positive feedback to act as the volume control. You adjust it for maximum volume just short of oscillation. Its the first time I worked on a set of this type.

The bad 300-A tube was weird. It has an intermittent internal short that continually makes/breaks/makes/breaks... as long as the filament is energized.

My next task was to complete the restoration of the cabinet.

The Cabinet

First, I removed ninety years of dirt and grime. I did not attempt to repair the nicks and other defects in the cabinet.

Then I brushed on a couple of coats of lacquer, lightly sanding with 600 grit paper in between coats. This was followed by a vigorous rubdown with nothing but a paper towel.

Refinished Cabinet
Reassembled

Then the chassis was reinstalled and the binding posts connected up.

There was an extra hole in the front panel. A small black snap-in hole cover doesn't look too bad filling the hole.

I had a lot of fun bringing this set back to life and restoring a piece of Montclair history. I hope you enjoyed the story.

    -Al Schapira, W2ADS

Please feel free to contact me at w2ads@arrl.net

Page last modified 04/17/2014