The C13 military wireless set.

keywords:  C13 wireless set, station radio, military radio, Larkspur, manual and schematics here
author: Ralph Klimek 2005
copyright:  my notes and observations and designs are free to all. HOWEVER, the manual and manual images are still copyright.

I had acquired one as a boy. It was a delight to behold. The insides appeared  miraculous. I had never encountered a truly complex electronic object before. Although I had no manual, I reverse engineered sufficient of it to biuld a control unit and power supply.

This device was to become the operational core of my ham radio setup, it become a stable source of carrier, a variable IF, and a source of frequency callibration as time when my hobby were financed through a bit of pocket money.   It taught me enough practical electronics to get me a job and see me through life.

I have searched for 30 years for a manual and schematic for this amazing piece of military history and I finally found one. It is scanned in its entirety and the images manually cleaned up.  

These images are low resolution thumbnails. Click on each to get the high resolution page  or download the entire manual tarball.

Given the extraordinary biuld quality of this set, if you are fortuneate enough to aquire one, it will probably just work without further ado.
If you are using the original vibratory supply, your 24VDC source must be clean because this voltage source is used for some low power requirement  biasing voltages internally.  A 24V vehicle battery supply was assumed.  Complete sets with all external harness and the elusive external ATU are extremely rare.  The ATUs were removed by surplus dealers for their Silver (Ag) content and very few ATUs made it into the hands of hams.   It is not difficult to replicate the basic functions of the external harness. You will require an external microphone amplifier should you wish to put it on air.

Here it is !

click here to download a tarball of all images including schematics.

This link takes you to the next  page of schematics


there were user servicable parts inside!

C13-N-manual0047.jpegC13-N-manual0048.jpeg C13-N-manual0049.jpeg
this is gorgeous! Do you think anybody ever did ? What would your adjutant have done?

This link takes you to the next page of  schematics

some internal images taken during a recent dust off, Jan 2010. I have not opened the case in twenty years. It still has the smell that is unique to the larkspur equipment... sweet rubbery  goodness !  Shown here is the reciever module swung out on its mainenance hinges. I did not have time to disconnect the front panel hardware to permit the transmitter half to swing out. Items of interest to look out for are the back of the ledex rotary relay on the sender module and some of the film strip dial and variable capacitor clockwork.  The transmitter bottle is mounted in a teflon socket and sits infront of a RF sheild that some very clever person saw to that it was finely polished and doubled as a thermal reflector, helping to passively dissipate the RF final bottles' heat against the aluminum case.  This radio was passively cooled unlike other larkspurs ( like the C42, C45 , C11 et al) that had a small internal fan.  Purists will note that the internal dessicator is missing. This vanished about 35 years ago. When I bought it ( I was only 16 at the time ) I did not recognise its function. Maybe it was a demollision charge! , or so I thought, so I quietly disposed of it.  I am still amazed at the very high component packing density.

This link takes you to the next page of  schematics

This link displays a page of my Power Supply Designs for the C13 wireless set

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this page was modified on Thu Apr 17 19:19:47 EST 2008 to improve useability and download speed
added email sig Tue Jan  5 18:29:07 EST 2010  Mon Feb  1 18:23:52 EST 2010 added pictures of C13 internals