A L I G N ME N T I N S T R U C T I O N S M A S T E R P I E C E VI
R.F. ALIGNMENT
At the left of the photo all trimmers are labeled for bands A, B, C, D and E, and for first and
second R.F. stages, first detector and oscillator. All high frequency trimmers should be aligned upon test
signals at frequencies specified below with the main tuning dial set to these frequencies:
A. 350 kc.
B. 1400 kc.
C. 5000 kc.
D. 16,000 kc
After the above high frequency alignment, the low frequency oscillator trimmers must be set.
This is done on the following test frequencies:
A. 175 kc.
B. 600 kc.
C. 2000 kc.
D. 6000 kc.
In this low frequency oscillator alignment, ONLY the oscillator low frequency trimmers are
adjusted. The method involves, for an example applicable to all four bands, tuning in on band B a 600 kc.
Signal with the tuning dial set at 600 kc. And then adjusting the B low frequency oscillator trimmer at the
same time that the tuning dial is rocked very slightly around its 600 kc. Setting in order to obtain the
maximum output meter deflection. In this low frequency alignment, dial calibration is of secondary
importance, and the alignment is intended to permit of accurate tracking between the UNTOUCHED r.f. and
the varied oscillator circuit by means of the low frequency oscillator trimmer adjustment in conjunction with
dial rocking to bring all four circuits into track. After the above low frequency oscillator alignment, high
frequency alignments should be rechecked for the above bands.
Band E has no trimmers and should never need alignment.
All above alignment instruction will require the use of an insulated screw driver or one having a
very short metal shank, particularly in D band alignment where the insulated screw driver is practically
essential.
Voltage check data is found in sufficient amount to indicate voltages to be anticipated at
different points in the circuit directly upon the diagram herewith. All voltage measurements must be made
with a high resistance voltmeter and should be plus or minus 10% of specified values.
