Elmer G. Osterhoudt
The Modern Radio Laboratories Catalog 

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MRL 1 Tube
MRL 1 Tube with Cabinet
On the left, MRL 1 Tube Radio rendering from the inside cover of MRL Detail Print File Number 2. Original drawing from MRL Radio Builder # 19 dated 1941. According to HB-5, Crystal Set Construction ( 1956), MRL used to sell the cabinet shown in the drawing. Reproduction of the radio in a similar cabinet made in 2021.

Cover of HB-4. This is one of the very few drawings Elmer made that has any perspective.
My perspective is that this doesn't have real perspective. The front panel is just a rectangle.

MRL 1 tube radio
Left knob controls the antenna tuning; the knob on the right is the regeneration control.

MRL 1 tube in catalog
MRL 1 tube in catalog
Catalog entry for the MRL 1 Tube DX radio.
Click on picture for the full catalog page.
In 1940 Elmer developed the MRL 1 Tube regen radio. The circuit is a typical regen but Elmer claimed he perfected the layout of the parts. He made a six page mimeographed "blueprint" named BP-2 which described the radio. After selling thousands of these the stencils disintegrated.

In 1954 he published HB-4, "MRL 1-TUBE D.C. ALL WAVE RECEIVER." The handbook describes every aspect of the radio and how to make every part of it. All data is included for making the plug-in coils.
Radio and Television News Jan 1954
This is an ad in Radio and Television News for plans to build the MRL 1 Tube radio.
The ad ran in January and March of 1954. Since the audience of the magazine was
mainly television repairmen and technicians, it probably didn't generate many sales.

Why gather all the parts and make the coils when you can just buy the kit from MRL? The kit came with two coils for the AM broadcast band but you had to buy the tube separately. Most tubes were $1. If you didn't want to build the kit, Elmer would build it for you for $3.

MRL 1 tube radio
At the time HB-4 was published, the price of the kit was $6.50. In 1946 the price was $4.95.
$4.95 in 1946 is equivalent to about $78.00 in 2024

MRL 1 Tube Schematic
The first 1000 copies of the handbook had the tube type omitted. After some inquiries by customers, Elmer made a rubber stamp and stamped the remaining copies. The later printings included the tube type, but he changed the value of C-5 from .0001 to .00048. This change was written in ink.

If you have a copy of HB-4 with no tube type listed on page 4, or a copy with the type stamped onto the page, it is quite a collectors edition (but nobody knows it).

MRL One Tube Radio
Oddly, this circuit was obsolete at the time Elmer printed the Blueprint in 1940. As a matter of fact, the manufacture of this type of radio had been banned sometime before 1924 and they were only obtainable as a kit. One tubers (sometimes called "Bloopers") can oscillate through the antenna and wreak havoc with other radios.

Crops from typical ads in 1934 for a 1 tube radio. Elmer never included a picture in any advertisement.
Notice the left one only picks up shortwave. It has a "blueprint," like Elmer's early radio plans.

So why did Elmer create this kit in 1940? This is purely conjecture, but 1930s radio magazines had many advertisements for one tube radio kits. By 1940 the ads had practically disappeared. That would make competition for MRL's one tube set almost non-existent.

The MRL 1 Tube radio works well, but requires patience to tune. Like a crystal set, it requires a set of high impedance headphones, also available from MRL.

MRL 1 Tube radio rear
Other MRL 1 Tube examples are here

Here you can see one of the changes made during the years. In 1952 Elmer could no longer obtain 140 pF variable capacitors, so he used a trimmer in series with a 350 pF cap. Notice the trimmer on the left is also shown in the drawing at the top of the page.

Later, he obtained two-section capacitors. He added an MRL-made switch to switch one of the sections in or out. The switch is closed for the AM broadcast band and open for shortwave.

MRL 1 tube Radio Kit
An unassembled MRL 1 Tube kit from 1980.
MRL variable capacitor
MRL switch
  MRL antenna tune capacitor. MRL switch.  
MRL OneTube Radio
"Compo." base with parts mounted by Elmer Osterhoudt.
MRL 1 tube radio base
Elmer mounted the sockets because people were putting them in backwards.

Elmer (or Mabel) wrapped the front panel in waxed paper. Something has gone through the paper and scratched the panel. No worries; in the instructions Elmer says to sand it and paint it.

Doug Wilson
This set was built by Doug Wilson in 1982. The vacuum tube is a 1C5-G.


MRL #18
Photo Thanks to Graeme Zimmer. Click for larger version.
Sorry, no photo of the assembled kit. You'll have to assemble it in your mind, like Nikola Tesla would do.
A picture of the completed front panel of a No.18 set can be seen on Page 7.
MRL #18
Here's another MRL No.18 kit. It dates from 1982.
Coils MRL no.18
Coils to the No.18. The one on the left looks like typical MRL QRM coil, however the secondary has 30 turns instead of 15. On the right is a QRM coil without the second winding. In operation, the left-hand coil slides in a track. As it comes into proximity with the right-hand coil the selectivity of the receiver changes.

The transistor seems to be a General Electric 2N1098 audio amplifier. They were sold in the 1973 through 1986 MRL catalogs for 99.

  In the May / June 1979 issue of "The Mother Earth News," Copthorne MacDonald wrote an article on crystal sets and listed MRL as a source for parts, and more specifically, the MRL No.2 Crystal Set.

In a letter from Elmer Osterhoudt to MRL customer Sloan Freeman, dated July 12, 1979, Elmer wrote that because of the article he sent out over 500 catalogs, and he had never sold so many crystal sets. Some people wanted the assembled kit, and he still had 19 sets waiting to be wired up at the time he wrote the letter.

It is interesting to see that the address for MRL begins with "DEPT TMEN." Of course, that would be short for The Mother Earth News, so EO seems to have been consulted before the article was published. He could then track how many orders resulted from the article.

Elmer was 80 years old at the time.

                             Click on the article to open a readable version


MRL mounting block


MRL Antenna Eliminator
MRL Antenna Eliminator
The factory-made Antenna Eliminator was once incorporated into a plug. It worked by plugging it into an AC outlet, which allowed you to use the house wiring as an antenna. The MRL version did away with the plug and just used a single spade. This is found in section G of the catalog, which listed antennas and accessories. By 1983 most of the items on this page were reduced to blank spaces. By 1986 section G no longer existed, though the index still referenced it. At that point, the antenna eliminator was only found only in the MRL Radio Flyer.


Two wooden blocks and screws (socket not included). 20 cents!
"MIP" means "Molded In Plate." The socket is molded into the mounting plate.

In 1970 Elmer and Mabel moved to 2612 Butano Drive, Sacramento, CA
Many of the Osterhoudt residences were one story with a garage. MRL was in the garage.