Heathkit SG-6 User Manual

For accurate calibration of home built receivers or equipment proceed as follows: make a rough
calibration with the signal generator. Then, with a receiver, tune in WWV (Bureau of Standards)
at 2. 5, 5, or 10 Mc. Set the signal generator to a suitable sub harmonic such as for instance 500
Kc, and adjust the generator for zero beat. Now the harmonics of the signal generator occur
very accurately every 500 Kc and these harmonics may be used to give accurate calibration
points at 500 Kc intervals such as 2,500'Kc, 3,000 Kc, 3,500 Kc, 4,000 Kc, etc. These known
frequency points can be marked on the dial of the equipment being calibrated. The object of the
rough calib:t'ation is merely to furnish a means of identifying for example the 3,000 Kc point
from the 2,500 Kc or 3,500 Kc points. For calibration of higher frequency equipment, a choice
of a higher sub harmonic will reduce confusion between the multitude of harmonics and will also
insure adequate signal strength.
When checking the calibration accuracy of the Heathkit Generator, the most convenient standards
of comparison, of sufficient accuracy, are broadcast stations of knownfrequency. Crystal oscil-
lators of standard frequencies, when zero beat against WWV, are also convenient to use, if avail-
able. The use of receiver dial calibrations is frequently not of sufficient accuracy to warrant
consideration.
USE OF R.F. SIGNAL GENERATOR
This Signal Generator can be used to align radio receivers. It furnishes a source of radio fre-
quency or modulated radio frequency by means of signal generator fundamental frequencies be-
tween 160 Kilocycles and 52 Megacycles (1 Megacycle=l ,000 Kilocycles) and useful calibrated har-
monics of the signal generator furnish output to over 150 Megacycles.
Wherever possible, the recommendations of the manufacturer of the radio being aligned should
be used. When this is not available, the following procedure can be followed.
Output Indication. With the new types of receivers, especially those using AVC (automatic vol-
ume control), a visual means of indicating resonance is desirable. If convenient, in all receiver
alignments, the A VC should be disabled during the process of alignment. Otherwise a signal
weak enough to not operate the A VC should be used .
IF Alignment. Connect the signal generator shield to chassis and clip the shielded wire to the
signal grid terminal on the converter tube socket. Set the signal generator to the IF frequency
required. RMA standard is 455 Kc, but other frequencies like 262 and 175 Kc are sometimes
used. Adjust generator output for minimum readable output indication. Adjust IF transformers
starting with the one nearest the second detector and working forward. The adjustment mecha-
nism consists generally of two screws which operate trimmer condensers, or iron cores inside
the coils. They may be located on top, on the side, or on the top and bottom of the IF transfor-
mer. Turn the adjusting screw for maximum output, reducing the signal generator output if nec-
essary to keep the output indicator from going off scale.
Oscillator Alignment. With the generator connected as above, set the generator dial to the high-
est frequency marked on the receiver dial (1,600 or 1,720 Kc). Set the receiver dial to this
same frequency. Adjust the receiver oscillator trimmer to bring in the signal. An additional
adjustment is often provided in the form of a padding condenser or an iron core. This is gen-
erally adjusted at 600 Kc and its final adjustment is made later.
RF Alignment. Using a 200 MMF condenser between generator and antenna post, set receiver
and generator to 1,400 Kc. Adjust antenna (and RF, if used) trimmer (frequently located on the
tuning condenser) for maximum output. Set generator to 600 Kc and "rock" tuning condenser
through the signal while adjusting the oscillator padder for maximum output at resonance.
For receivers with a loop antenna, couple the signal through a single turn loop connected to the
generator output.
Tuned radio frequency receivers are aligned as shown under RF Alignment.
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Heathkit SG-6 Specifications

General

Brand	Heathkit
Model	SG-6
Category	Measuring Instruments
Language	English