Elmer G. Osterhoudt
The Modern Radio Laboratories Catalog 

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Below is a list of Modern Radio Laboratories® literature (incomplete.)
Note: Many of the following MRL publications can be found here.
Handbooks, Data Sheets and Detail Prints can be found here.
          Missing publications will be added (if found) here.

MRL Handbooks:

HB-1 Headphones: Operations and Repair   ©1948
HB-2 No. 2 and 2-A Long Distance Crystal Sets   ©1945
HB-3 Crystal Detectors   ©1938, 1954
HB-4 1-Tube D.C. All Wave Receiver   ©1953
HB-5 Crystal Set Construction   ©1956
HB-6 How to Make Coils   ©1957
HB-7 Experiments with Magnetism and Coils   ©1957
HB-8 Radio Kinks and Quips   ©1958
HB-9 Radio Notes No. 1   ©1959
HB-10 Facts for Crystal Experimenters   ©1960
HB-11 Radio Operating as a Career   ©1961
HB-12 Radio Workbench Tips   ©1962
HB-13 Radio Notes No. 2   ©1964
HB-17 MRL 20 Crystal Set Circuits   ©1951
HB-25 MRL 18 Crystal Set Circuits   ©1947

MRL BLUE PRINTS No known copies. Unknown number of issues.

These early documents were designated "BP" or "Blue Print." The mimeograph stencils for the BP series wore out, or in some cases, disintegrated.

BP-1 -  Published in 1932. May have described the MRL No. 1 crystal set. (Not verified.)

BP-2 -  Written in 1940, six pages long. (1 Tube D.C. All-Wave Receiver)
            Replaced with HB-4 in 1953.

BP-3(?) - "Crystal Detectors." Copyright October 12, 1938.  Replaced with HB-3 in 1954.

BP-17 - "18 Crystal Set Circuits." Published in 1934.
             Replaced with HB-17 "20 Crystal Set Circuits" according to "Radio Notes No. 2"

BP-25 - Replaced with HB-25 "18 Crystal Set Circuits."
             Note: Both BP-17 and HB-25 were both titled "18 Crystal Set Circuits."

     There were 7 Blue prints in 1934, according to a 1934 "Radio World" ad.

MRL OSCILLATOR No known copies. Unknown number of issues.
MRL OSCILLATOR #1 Published 1933.
MRL OSCILLATOR #2 Published 1934.
MRL OSCILLATOR #3 Published 1934.

MRL Radio Builder & Hobbyist (called "Radiobuilder" in MRL ads)
RB&H-9 was printed prior to 1937, so we may assume Elmer began RB&H-1 soon after
          ending publication of the "MRL OSCILLATOR"

RB&H-1 to 25 - No known copies. All that is known is that number 19 was published in 1941.
RB&H-26, 30, 31 & 32 - No known copies. All replaced with HB-13
RB&H-33  No known copies
RB&H-34  All unsold copies lost in 1959 while relocating. Replaced with HB-9
RB&H-35  Published in 1953
RB&H-36  Published in 1953 or '54
RB&H-37  Published in 1954
RB&H-38  Published in 1954
RB&H-39  Published in 1954
RB&H-40  Published in 1955
RB&H-41  Published in 1955
RB&H-42  Published in 1955
RB&H-43  Published in 1956
RB&H-44  Never published
RB&H-45  Never published
RB&H-46  Never published, HB-7 given to subscribers in lieu of. (1957)
RB&H-47  Never published

RB&H-48  Dated "Spring 1959."
RB&H-49  Last issue, dated "Summer 1959."

Note: RB&H-25 to 40 were still available from MRL in 1970 for 15¢ each.
          Issues 41, 42, 43, 48 and 49 were 25¢. Elmer stated that no new ones were
          being printed and supply was low.

          Circulation of RB&H was over 3500 customers per issue.

MRL Experimenter’s Electronics and Science
Very similar to RB&H but with a more polished look. In  booklet form.
Covers a variety of topics in addition to radio.

ES-2 Published 1961.

MRL Data Sheets
These  are similar to RB&H in content but lack the "Editorial Noise Level" section.

DS-6 Published in 1966.

MRL Detail Print File

Vol-1 ©1958
Index (plus article on Static)
DP-1 MRL No.37 Push Button Crystal Set
DP-2 MRL No.33 Selective Crystal Set
DP-4 15 One-Tube DC circuits
DP-11 MRL Type D Antenna Coupler
DP-12 MRL 2 Stage Transistor Amp
DP-13 MRL All-wave Vario-Coupler
DP-14 MRL Transistor Small Set Amplifier
DP-22 MRL No. 2 Long Distance Crystal Set
DP-22A MRL No. 2-A (variation of above)
DP-23 MRL No.8 Crystal Set
DP-26 MRL No.1 DX Crystal Set
DP-28 Radio and Electrical Symbols
DP-30 Proper Aerial & Ground Construction
DP-34 MRL No.10 All Wave Crystal Set
DP-41 Code Short Cuts

Vol-2 ©1961
Index (plus Regen info)
DP-16 MRL Portable Transistor Amplifier
DP-21 10 Tested Crystal Set Circuits
DP-24 MRL No.9 Selective Crystal Set
DP-25 The Flextal Crystal Set
DP-29 MRL 1-Tube Triode DC Short Wave Receiver
DP-31 MRL 2 Tube AC All Wave Receiver
DP-33 MRL Pocket Radios No's. 7-19-32
DP-38 MRL 6 Watt Class B Power Amplifier
DP-39 16 Tested Transistor Circuits
DP-43 MRL No.26 Single Dial All-Wave Crystal Set
DP-47 MRL No.28 All Wave Plug-in Coil Crystal Set
DP-57 MRL 1 Tube Shortwave Converter
DP-63 MRL 2 Tube All Wave DX Receiver
DP-64 MRL No.3 Selecto-dyne Crystal Set
DP-69 MRL No.12 Improved Slider Crystal Set

Vol-3 No copyright listed.
Index (plus long wave article)
DP-6 MRL No.39 Selective Crystal Set
DP-18 MRL QRM Coil Transistor Set
DP-19 & 19A Navy Type Loose Coupler
DP-27 MRL No.15 Crystal Set
DP-35 MRL 2 Tube Long Wave Receiver
DP-36 MRL 2 Tube "EC" Long Wave Receiver
DP-44 MRL No.29 Variometer Crystal Set
DP-48 MRL No.35 Prize Selector Crystal Set
DP-49 MRL Heavy Duty "No Hum" Power Supply
DP-56 MRL No.11 DX All-Wave Crystal Set
DP-58 MRL No.4 Telefunken Crystal Set
DP-59 MRL All-Wave Crystal HiFi Adaptor
DP-61 MRL "50 in 1" Antenna Tuner
DP-73 Supplement to HB-4
DP-74 MI “Original Radio” Crystal Set. Described a crystal set published in "Mechanics Illustrated."
          Written sometime around 1970, it seems to be the last MRL publication.

In addition to the annual MRL catalog, the "Radio Flyer" was published, which included revisions to the catalog and "Random notes from Modern Radio Labs." Only Radio Flyer No. 1, 3, 6 and 23 have been found.

Where are the missing publications, especially the first 33 editions of "Radio Builder & Hobbyist?" After Elmer's death over 100 wet and corroded printing plates were found with his printing press. How they got wet is not known, but what was on them is lost to us. Some documents have been found and are published on Page 11 here.

MRL Mystery: What was Elmer's method of numbering? If there were 7 BP's in 1934, why is BP-2 dated 1940? In 1955 Elmer wrote that he had six handbooks. They were # 1, 2, 3, 4, 17 and 25. Why did the volume number jump from 4 to 17?


A mimeograph machine made by the A. B. Dick company. Elmer may have used a similar one in the 1930 and '40s.

The MRL "business plan" was simple. Elmer placed vaguely worded advertisements in various magazines, such as the one above from a 1938 copy of "Popular Mechanics." If you were interested, you sent your 25¢ to "Laboratories."
You would then get HB-25, "18 Crystal Set Circuits," and a copy of "Radio Builder and Hobbyist" in the mail, along with a catalog. Three more "Radio Builder" booklets would follow during the year.
Contents of HB-25
Here is where Elmer's knack for business comes in. All of the crystal sets in the handbooks and "Radio Builder" used MRL parts! Though Elmer gave detailed instructions on how to make the various coils and gadgets, he also sold them. If you wanted to wind the coils yourself, MRL sold the coil forms and wire. MRL sold every part needed to make the radios listed above, and also sold the kits so you didn't have to order each part separately. Of course, you'd need a nice pair of headphones, too.

Elmer once wrote, "We've been accused of pushing our own parts - (the very idea!)."

Elmer threw in a brief handwritten note and a random "Detail Print" with the order to keep your interest piqued. Then three months later the next issue of "Radio Builder and Hobbyist" would arrive in the mail, just in case life got in the way and you forgot you were supposed to be building a radio. If you already built one, "Radio Builder" would whet your appetite to build another one!

The first page of the catalog covered postal rates, followed by a small "Let's get acquainted" introduction to MRL.
The next page described the first three handbooks.
The following pages described more handbooks, after that came the Detail Prints and other publications.
This went on for eleven pages!!

After Elmer wrote a Handbook, Mabel Osterhoudt typed it on a Varitype machine. Elmer would then print them with a lithographic printer. According to the text in the picture, this is just what they needed for all those catalogs and handbooks.

In the 1930s Elmer referred to the publications as "blueprints" because they were mimeographed. All of the MRL publications are black and white (or blue and white). The cover of the handbooks were usually printed on a colored piece of paper.

Mabel also sent out orders, typed and assembled the pages of the Handbooks, turned boxes of parts into kits and kept the company on schedule. Elmer did the bookkeeping, manufactured parts, bought supplies and created the literature.

Almost all the surviving handbooks have a copyright date from the 1940s and 1950s.

Some of the handbooks say they are combinations of previous publications or that the mimeograph or lithograph plates wore out, so a new handbook was written. HB-3, "CRYSTAL DETECTORS," states, "Copyrighted 1938. Re-written and copyrighted 1954." It would be interesting to see the 1938 version of HB-3 if any still exist.

This is a "Multilith" printer model 1250, the model Elmer used. According to "Radio Builder and Hobbyist No. 35," his printer cost him $2,400 and could print 6000 pages an hour. Paul Nelson of MRL refurbished it into beautiful working condition in the 1990s.

Elmer stated that MRL used over a ton of paper per year and that it took three days to make one catalog page up from scratch before printing it. When he printed up a new batch of catalogs he sometimes did 1000 at a time. To print a 54 page catalog he had to feed 54,000 pages through the printer. The 28,000 pieces of paper then had to be stacked in proper order and stapled together into 1000 individual catalogs.

It would have taken 56 reams of paper, gallons of lithograph ink and 1000 staples IF everything worked perfectly.

As time went by you'd end up with everything Elmer printed, as in this staged photo. This MRL literature and the radios are from the 1980s.
More marketing. On the backs of these ten handbooks are descriptions of other handbooks!
From what Elmer related, all of this was typed by Mabel, but it must have been a team effort.


Here's an example. This is the back cover of "Facts For Crystal Experimenters." It describes HB-9, "MRL Radio Notes No. 1." It states that the basis of the book was Radio Builder #34, which is out of print.

The first of the "questions answered" is "Building an efficient tuned Radio frequency stage for any type of radio. All wave. Page 3."
 (What? Really? I'll take a copy!)

Looking at the rest of the index there is something that you'd want to read about, and it was only a buck in 1983. You didn't know it but that 25¢ handbook, which was now a dollar, was half price due to inflation. It should have been two dollars.

Elmer advertised MRL in MRL publications for MRL customers.

Click on it and see
what I'm sayin'.

The handbooks, Detail Prints and Data Sheets were chock full of crystal set circuits, many of which required multiple MRL coils. In "18 Crystal Set Circuits" there is an all-wave circuit requiring a complete set of MRL plug-in coils. Another uses a MRL variometer. Several use the MRL QRM coil ahead of the main circuit.

In HB-13, "RADIO NOTES NO. 2," on page 18 there is mention of an "old Experimenter" who went into business for himself after wearing out many MRL Handbooks. For more details you need to get HB-11, "RADIO OPERATING AS A CAREER." If you were interested you sent for HB-11 and since you were sending for HB-11, you might as well send for a few others and some coils and crystals and switches, etc. When your order arrived you'd get a note from Elmer which made you feel like a valued customer.

(In HB-11 there is no mention of that particular "old Experimenter," much to my disappointment.)

Click for full cover page.
If you placed an order, an MRL RADIO FLYER would sometimes appear in your mailbox. Radio Flyer No. 1 was a single page. Radio Flyer No. 23 was a dozen pages of updates and additions to the catalog. Tips for making your MRL radio perform better were included, along with other small radio related articles. Cartoons and jokes were placed at various places so that it was entertaining to read.

If that wasn't enough, Elmer didn't like the Post Office to make any extra money, so if your order weighed 1.5 pounds and the postage was 2 pounds, he'd stuff a half pound of literature in the box.

No need to look for an envelope. MRL sent envelopes and order forms to you with the catalog.
On the envelope was a drawing of the MRL 1-Tube radio and the MRL No. 2 Crystal Set.

Around 2003 Paul Nelson restored Elmer's Lithograph printer and printed the entire remaining catalog of MRL documents on high quality, acid-free paper. The set sold for $34, which was quite a bargain. 
An interesting observation about the handbooks are their size. A "standard, letter size" piece of printer paper is 8½ x 11 inches in dimension. The MRL handbooks, when opened, are 8¼ by 10½ inches. To make copies of the handbooks, Paul Nelson had to cut every piece of paper to 8¼ by 10½.

Why are the handbooks this size? Another MRL mystery. To add to the enigma, they are advertised as being 5½ x 8½. This is the size of standard printer paper when folded in half! Were they printed on standard size paper at one time? Did Elmer chance upon a large supply of off-size paper that nobody wanted, and the price was right? We may never know.

Popular Science, June 1949.
This is vague even by MRL standards. Personally, I wouldn't have given this a second glance. Popular Science charged 80¢ a word in 1949, so this ad was about $12.00. That's the equivalent to $130.00 in the year 2020. Perhaps Elmer should have thrown in a few more words. By the way, 3 issues of "Radiobuilder" for 25¢ was a deal.

Here's another Varityper machine, but more sophisticated. A Varityper could type both left and right justified print.
It was a marvel of engineering but this one looks like a "creature from beyond space," eating a woman's fingers.
He must be her type! (Groan. That was awful.)

Friendly competitors: Leslie Hulet, Joe Amorose, Alva Allen

Leslie Hulet
Here's Leslie Hulet's ad from the back of RB&H No. 41, printed by MRL in 1955. What did you get if you wrote to him? In Popular Mechanics, he offered "free information," whereas Elmer requested 25¢. From 1944 to 1955 Hulet posted more ads in Popular Science and Popular Mechanics than Elmer Osterhoudt did. They are basically all the same as above.

Hulet made several contributions to "Radio Builder and Hobbyist." No.35" contains "
A NICE LETTER FROM LES HULET" followed by Elmer's response. Issues 48 and 49 contain a column titled "Les Hulet Reports."
Hulet won 3rd prize in a contest by Short Wave Craft in 1932, the same year Elmer started MRL. Page 349

Elmer and Leslie were competitors but seemed to be friends, though 3000 miles separated them.  The same relationship existed with two other competitors, Joe Amarose and Alva Allen.
Joe Amorose's ad from RB&H No. 38, printed by MRL in 1954. Amorose had been experimenting with crystal radios since 1920 and contributed articles to Science and Invention in the 1930s and Radio & Television News in the 1940s.

In RB&H #35, Elmer published a letter written by Joe Amarose boasting that a man in Richmond, VA picked up Moscow, Canada, Mexico and Cuba on an Amarose crystal set. The set used MRL coils. The radio plan was published in the October 1952 edition of Radio Electronics, page 102.

Alva Allen
Alva F. Allen ( 06/19/1900 - 01/06/1987) had been making crystal sets since the 1920s. He sold crystals and crystal sets. An edition of his newspaper, The Magic Crystal can be found on page 11 here. In it, Allen states he is a "manufacturer and distributer" and has hundreds of letters in his files reporting long distance reception.