Heathkit SG-8 Assembly And Operation Manual page 4

I
The power apply consists of a transformer which furnishes filament voltage to the 6C4 and
12AU7 tubet and effectively isolates the instrument from the AC line. A selenium rectifier is
connected
t<
one winding of the transformer producing half-wave rectification. An RC filter
network cha iges the pulsed output from the rectifier to fairly pure DC. The 110 volt input has
both sides bypassed to minimize the signal feeding back through the power lines.
A unique de ugn feature is the convenient AF IN-OUT control, which adjusts audio input if ex¬
ternal moduation is employed and likewise adjusts theAF output level when using the generator
as a source of audio output.
9
PRELIMINARY INSTRUCTIONS AND NOTES
TheHeathki model dG-8 Signal Generator when constructed in accordance with the instructions
in this mam al, is a high-quality piece of test equipment, capable of years of trouble-free serv¬
ice. We therefore urge you to take the necessary time to assemble and wire the kit carefully.
You will be rewarded with a neat appearing, well-built and dependable test oscillator.
This manual is supplied to assist you in every way to complete the signal generator with the
least possit le < hance for error. We suggest that you take a few minutes now and read the en¬
tire manual thr )ugh before any work is begun. This will enable you to proceed with the work
much faster wl en c instruction is started. The large, fold-in pictorials are handy to attach to
the wall above your work space. Their use will greatly simplify the construction of the kit.
These diagrams are repeated in smaller form within the manual. We suggest that you retain
the mamal in your files for future reference, both in the use of the signal generator and for its
mainten mce.
UNPACK THE KIT CAREFULLY AND CHECK EACH PART AGAINST THE PARTS LIST. In
so doing, ycu will become acquainted with each part. Refer to the charts and other information
shown on tho inside covers of the manual to help you identify any parts about which there maybe
a question. If some shortage is found in checking the parts, please notify us promptly and return
the inspection slip with your letter to us. Hardware items are counted by weight, and if a few
are missing, please obtain them locally if at all possible.
Read tho note on soldering on the inside of the back cover. Crimp all leads tightly to the termi¬
nal before soldering. Be sure both the lead and the terminal are free of wax, corrosion, or
other foreign substances. Use only the best rosin core solder, preferably a type containing the
new activated fluxes, such as Kester "Resin-Five, " Ersin "Multicore," or similar types.
NOTE:
GUARANTEES ARE VOIDED AND V/E WILL NOT REPAIR
1ENTS
USED.
DRE SOLDER OR PASTE FLUXES HAVE BEEN
SOLDER, IT IS RECOMMENDED THAT A NEW
IN DOUBT ABOUT SOLDER, IT IS REC
' MARKED "ROSIN CORE RADIO SOLDER
Resistors and condensers generally have a tolerance rating of ±20% unless otherwise stated in
the parts list. Therefore a 100 KO resistor may test anywhere from80Kft tol20Kfi. (Thelet¬
ter K is commonly used to designate a multiplier of 1100.) Tolerances on condensers are gen¬
erally even greater. Limits of +100% and -50% are common for electrolytic condensers. The
parts furnished with your Heathkit have been specified so they may not adversely affect the op¬
eration of the finished signal generator.
In order to expedite delivery to you, we are occasionally forced to make minor substitutions of
parts. Such substitutions are carefully checked before they are approved, and the parts sup¬
plied will work satisfactorily. By checking the parts list for resistors, for example, you may
find that a 2.2 megohm resistor has been supplied in place of a 2 megohm as shown in the parts
list. These changes are self-evident and are mention'd here only to prevent confusion in check¬
ing the contents of your kit.
We strongly urge that you follow the wiring and parts layout shown in the manual. The position
'age 4