Magnetron tuning arrangement features a means of moving a tuning ring axially within an anode cavity by a system of reduction gears engaging a threaded tuning shaft of lead screw. The shaft positions the tuning ring for the desired magnetron output frequency, and a washer prevents backlash

Martucci, V. J.

English

NASA Technical Reports Server

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April 1969	 Brief 69-10119 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Magnetron Tuner Has Locking Feature 
Belleville Washer 
t2 
Use of a tuning element to control frequency in an 
electron discharge device, such as a magnetron, is well 
known. Tuning is usually achieved by selectively con-
trolling the positions of metallic or dielectric elements 
within cavities, formed by electrodes. If the frequency 
is not critical or the magnetron is easily accessible for 
frequent tuning, a relatively simple arrangement may 
be used. If, however, a very precise frequency is re-
quired and the magnetron is not readily accessible for 
frequent maintenance, it is necessary to finely tune the
elements and insure that they remain so positioned 
regardless of environmental conditions of vibration, 
shock, or the range of temperature encountered in a 
given application. For example, in one application, a 
dielectric tuning ring has been used to adjust the mag-
netron frequency at a rate of 18 megacycles per 
0.001-inch of ring travel. In this application, it is nec-
essary to move the tuning ring at a very slow travel 
rate and, when once set at the desired frequency, to 
maintain the setting in the presence of the anticipated 
(continued overleal( 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States 	 will be free from privately owned rights.
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adverse environmental conditions, to hold the magne-
tron output frequency to within ± 1 megacycle. 
Existing tuning arrangements have proven inade-
quate to meet these requirements. Therefore, a new 
arrangement has been devised that will satisfy all re-
quirements with a minimum of maintenance. 
This new arrangement features a means of moving 
a tuning ring axially within an anode cavity by a sys-
tem of reduction gears engaging a threaded tuning 
shaft or lead screw. The shaft is moved up or down at 
an extremely slow rate to position the tuning ring 
within the anode cavity so that the desired magnetron 
output frequency is achieved. A Belleville washer in 
the upper assembly exerts a constant biasing pressure 
on the tuning shaft to prevent backlash during the 
tuning operation. A bellows within a bellows housing 
encloses the tuning shaft to permit axial motion of the 
tuning sleeve without disturbing the pressure balance 
within the device. The bellows retainer terminates in 
hardened fingers that produce interfering tolerances 
on a minimum circumferential surface between the
i.d. of the bellows retainer and the o.d. of the tuning 
sleeve. 
Notes: 
Documentation is available from: 
Clearinghouse for Federal Scientific 
and Technical Information 
Springfield, Virginia 22151 
Price $3.00 
Reference: TSP69-101 19 
Patent status: 
This invention is owned by NASA, and a patent 
application has been filed. Royalty-free, non-ec1usive 
licenses for its commercial use will be granted by 
NASA. Inquiries concerning license rights, should be 
made to NASA, code GP, Washington, D.C. 20546. 
Source: Vincent J. Martucci
of Metcom, Inc.
under contract to
NASA Pasadena Office
(XNP-09771)
. 
S 
Brief 69-10119	 Category 05


Magnetron tuner has locking feature

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