SKY CHAMPION MODEL S-20R
OPERATING INSTRUCTIONS
The Hallicrafters Co. believes that, without exception, the model S-20R receiver represents the best
value in the communications field. This instruction booklet, when studied and carefully followed will
help you to better understand and appreciate your Sky Champion so that you then will be able to obtain
all of the characteristics of excellent performance for which this model is noted.
It is recommended that, upon receipt, the owner of the S-20R receiver carefully inspect the carton and
then the receiver for any damage which might have occurred in transit. Should any signs of damage be
apparent immediately file claim with the carrier accurately stating the extent of the damage.
ANTENNA
The Sky Champion has an antenna input circuit which will allow the use of either a doublet or Marconi
(inverted "L") antenna. The approximate antenna input impedance of the S-20R is 400 ohms.
A very serviceable antenna will be the inverted "L", or Marconi type. This antenna should be
approximately 75 feet long overall, including the lead-in to the set. Satisfactory operation of the
Sky Champion is obtained throughout its tuning range with this type of antenna and because of that
fact as well as its ease of construction it is highly recommended.
With the inverted "L" type of antenna terminal A2 must remain connected to terminal G for best
operation. While a ground connection is usually not necessary it might prove to be helpful in
reducing noise. A cold water pipe or 6' foot rod driven in moist soil will be a very satisfactory
ground when connected to the G terminal on the receiver. Connections to a radiator or gas piping are
not recommended.
Should a doublet antenna be used it is suggested that a 400 ohm transmission line be constructed so
that a most efficient transfer of energy is obtained. The commercially available all wave doublet
antennas are usually provided with a coupling transformer which matches the transmission line to the
receiver. This transformer connects to the AI and A2 terminals on the antenna terminal strip. The
half-wave length-doublet antenna cut for a particular frequency can be computed by the following
formula.
Length in feet = 463 / Frequency in megacycles
or for example, a half wave 20 meter or 14
megacycle antenna would be
463/14 or 33.7 feet long overall
This type of antenna is broken in the center with an insulator and has the transmission line connected
to each resulting quarter wave section at that point. This antenna is a very good performer, in a
direction broadside to its length, only on the relatively narrow group of frequencies for which it was
cut. It does not function well on harmonic frequencies.
When using either type of doublet antennas the transmission line should be connected to binding posts
A1 and A2. The wire connecting the terminal A2 to ground or G can be left connected if the performance
of the receiver is improved.
FREQUENCY RANGE
The Sky Champion tunes from 550 kilocycles to 44 megacycles in four bands. The frequencies covered per
band are as follows:
Band
Coverage
1
550 KC to 1,780 KC
2
1.74 MC to 5.4 MC
3
5.3 MC to 15.8 MC
4
15.5 MC to 44. MC
