Elmer G. Osterhoudt
The Modern Radio Laboratories Catalog 

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MRL no. 2 front panel
Alfred P. Morgan front panel
  MRL No. 2 Morgan crystal set  Page 92  
There seems to be a clone of the No. 2 Crystal set in the book "FIRST RADIO BOOK FOR BOYS" by Alfred P. Morgan, Copyright 1941. The picture from Morgan's book is on the right. Alfred P. Morgan wrote over 15 books on radio. Would he copy Elmer's circuit into one of his own books?
  MRL No. 2   Morgan Circuit  
They certainly look similar. Which circuit works better? I tried it both ways. The fact is, the Morgan circuit doesn't work at all. The problem is the variable capacitor in series with the coil tap selector. A person named Hue Miller emailed and wrote that there is a mistake in the Alfred P. Morgan circuit.

BS detector
All modern AM radios need a "BS" detector and switch!
The term "BS" or "Bullsh*t" didn't become popular till after WWII. Morgan's book is copyright 1941.


MRL radio coil
MRL No. 2 coil
Here are two examples of the MRL No. 2 coil. The one with the fiber rings at the ends is the oldest, but they both show signs of the celluloid shrinking from age.
Modern Radio Labs No. 2 coil
An unused No. 2 coil from the 1980s.
The coil form is 2" in diameter by 4.5" long. The coil is 90 turns of #22 cotton covered wire, tapped at turns 5, 10, 16, 23, 40, 50, 61 and 73.

What formula did Elmer use to determine the taps? Did he calculate the inductance of each tap and determine the frequency the coil will resonate at depending on the position of the variable capacitor?
coil taps
It seems he used a ruler! The coil is tapped at 1/4, 1/2, 5/8, 3/4, 1½, 1¾, 2, and 2½ inches.

Another MRL Advertisement

Electronics Illustrated Dec 1958
In November of 1958, "Electronics Illustrated" magazine announced they were accepting classified ads. This MRL advertisement appeared in the very next issue.


MRL 2XM coil form
If you saw this in the catalog, what do you think it would actually look like?
MRL coil form
It's a beautiful, hand-made, low loss, high-Q, transparent celluloid coil form. 2" in diameter x 4.5" long.
According to an advertisement in Radio magazine, the first 2" celluloid coil forms were sold in July of 1934.
MRL catalog page F4
The 2XM coil form is the heart of many of the crystal set kits and plans in Elmer's literature. The cost in 1972 was 45¢. In 1985 it was a dollar. An MRL-made mounting bracket was included. This bracket was not sold separately in the catalog.

MRL No. 18 Diode-Transistor Set

MRL #18
MRL #18
Catalog entry for the No. 18 and an actual No. 18 built in 1980.

MRL No. 26 Diode-Transistor All Wave Set

MRL #26
MRL #26
Catalog entry for the No. 26 and an actual No. 26 built in 1978 by Sloane Freeman.
MRL no. 26
Another MRL No. 26, this one built by Don Holdaway. That brass switch looks new!

MRL No. 10  All-wave Diode-Transistor Set

MRL #10
MRL #10
Catalog drawing for the #10 and an actual #10 built over 50 years ago.
The kit came with all the parts, a 4.3 volt battery and a copy of DP-34. It sold for $8.50.
MRL no. 10 All Wave
Rear view of the MRL Number 10 shown above. This was built in 1971.
On the left is the battery holder, but the battery and connecting wires are missing.
MRL #10 All Wave Crystal Set
Notice the 2 gang variable capacitor.
MRL #10 All Wave Crystal Set
This address dates the radio to 1971 - 1972
MRL no. 10 circuit
mercury battery

The 4.3 volt Mercury battery is so rare I can't find a picture of one.
According to the catalog, the battery holder will fit an AA or a 4.3V mercury.
MRL trivia: Elmer sold Burgess batteries because you could solder to the negative side, unlike other brands.



MRL Variometer
MRL Variometer
  1973   1986  
Here's another drawing that is ambiguous, as is the statement "has never been listed in CAT." How can it not be listed in the catalog if you're looking at it in the catalog? Obviously, it was only intended for the first catalog to list the variometer but the line stayed in for all the other catalogs.

What is it? What does it look like in real life?
The catalog hints we should get DP-44. Here is the variometer in DP-44, drawn actual size in the publication. Unfortunately, Elmer's drawing shows it as viewed perfectly down from the top. It looks like two rectangles in a square inside a circle.

MRL Variometer
The square and the circle are cylinders!
MRL Variometer
MRL Variometer
The rectangles are coils!
MRL Variometer
Two different sizes.
MRL Variometer
MRL Variometer
The coupling between the coils is varied by turning the inside coil.

MRL Variometer
MRL Variometer
Another MRL masterpiece! How many of these would he have sold if he had put a picture of one in the catalog? If you scroll back up and look at DP-44 again, you'll see he has a picture of a "1920 - 1930 Low - Loss Variometer" next to his drawing. Why didn't he use a photo of his own variometer??



MRL #16 Amplifier
MRL #16 Amplifier
Radio Builder and Hobbyist No. 48 states this became available on May 1. 1959, but in a round plastic box.
MRL #16 Amplifier
MRL #16 Amplifier
This is an unassembled kit from 1986. If you purchased it already wired, a 9V battery was included.
MRL amplifier box
MRL amplifier box
MRL amplifier box
The most interesting aspect of the kit is the box! Elmer made a wooden box, then covered it with wood grain Contact Paper. How long did that take? Why didn't he paint it with the same paint as the front panel?
Transistor Amplifier changes
An explanation of the box, from MRL Data Sheets Vol. 6

Look at the underside of the front panel in the middle picture. We've just solved the mystery of what Elmer calls "Compo." It's Masonite!

Note: In HB-5, Crystal Set Construction, page 3, Elmer stated that "Compo." is Masonite. However, HB-5 wasn't published till 1956 and he had been calling it "Compo." for two decades prior.


MRL RF choke
MRL RF choke
MRL RF choke
Catalog picture. Envelope from MRL. Choke contained in envelope.

Misprint in the February 1959 edition of Popular Electronics. Fortunately it only ran for one month.

411 Capitol Hill Avenue Reno, Nevada
In 1951 Elmer and Mabel moved 250 miles from San Carlos California to this house at 411 Capitol Hill Avenue in Reno, Nevada. The house was built in 1941. A year later they moved to Redwood City, California. San Carlos and Redwood City are only 2.5 miles apart.
                             In 1971 Elmer and Mabel moved from Sacramento, California to this house in Reno, Nevada.  

Why would they move to Reno, Nevada? Twice. In 1984 Elmer wrote that years previous Mabel would sometimes go to Reno for a week. During that week he'd go into the shop at 6AM and write a handbook. Apparently there was something about Reno that appealed to Mabel. Elmer said they didn't gamble, that was for the tourists.

A year later they moved to Garden Grove, California. It was only a two hour drive from Sacramento to Reno in 1971, but the trip from Reno to Garden Grove is over 500 miles and would have taken all day. Every time they moved, they moved seven and a half tons of MRL with them.