ARN-52 unit in Starfighter F104 format

Only the modulator and power supply are solid state, all other units have only tubes.

The  regular  ARN-52 is built in a square box with a standard 45-pin connector like the ARN21.

The Starfighter version shown here  has a slightly different shape to fit in the F104G Starfighter avionics bay and has two 34-pin M-series connectors. The unit was made by Standard Electric Lorenz (SEL)


Circuit diagrams are here:

 - RF  module ( PA,  oscillator/multiplier, IF amplifier and modulator)

 - Range circuits   (Decoder, A , B and mech. module, SelfTest and Limited Search option)

Azimuth circuits ( Decoder, A, B and mech. module, magnetic amplifier)

Power supply , backplane relays, main connectors.

In 1963, the ARN-21 was followed up by the ARN-52, supporting the A-A mode, built-in indicator couplers,  a bidirectional azimuth search, and fast short-range search. Except for the modulator and power supply, all units still have  tubes..



TACAN sets





A tribute to its inventor, Sven H. Dodington.



The two black modules on the top row contain the mechanical servo/synchro systems for range and azimuth. These  indicator couplers match with specific indicators like the Course Deviation Indicator (ID-249 ) and Radio Magnetic Indicator ( ID-250) . The Starfighter version matches with the PHI-4 indicator.  The bearing module has a synchro output to drive the CDI and  RMI instruments, while the Range module has two potmeters  for the autopilot and  PHI-4 indicator.


The other modules on the top row are the Bearing ( -decoder , -“A” and -“B” ) modules,  and the Range (-decoder, -“A” and -“B”) modules, on the lower row are the RF module, magnetic amplifier and the power supply .  The large module (lower left)  contains all the RF parts. The backbone of this module is the gold-plated cavities block with  four 2C39A type disc triodes as drivers and final amplifier . ( Shown below in upside-down position)  The cavities are pressurized and tuned with a long shaft, which also rotates  1) a  turret with 126 crystals, one for each channel , 2) the  multiplier tuned circuits , 3) at the far end the Preselector cavities for reception, and 4) the position feedback potmeters.  Also attached to the RF module frame are on the frontside  the oscillator / multiplier, and the IF amplifier, and on the rear side  the (solid state) modulator and the channel motor controller.