Evening star., 1925-12-29
FIFTEEN MINUTES OF
RADIO EACH DAY
BY JOSEPH CALCATERRA.
AL Rights Reserved. Repro. Prooio,teo'
How to Build the B-T COunterphase
Six Receiver Part i.

Any discussion Of the best in radio
receivers or circuits usually centers
about the qualities most desired in any
type of radio receiver. There are GER
tain we'll defined characteristics which
Immediately stamp any circuit or re-
ceiver as good. bad or Indifferent.
One Of the most important charac-
teriStics Of any receiver in this day OF
numberless broadcasting stations is
the ability of set to separate sta
tions. No radio set that cannot cut
through powerful local stations in
congested areas and reach out for the
distant stations will satisfy the criti-
cal radio fan who has been schooled
to accept nothing but the best
Tone Feature of Set.
The music lover must also be salts
fed. and this can only be done by
producing an instrument in which
each part has been specially designed
to function with every other part used
III the set. Good tone quality in re
cetver is the result OF careful design
OF individual parts and proper location
of those parts with respect to each
other
The days when piercing whistles
and howlS were taken as necessary
evil in the adjustment of a receiver
are over. Whistles and howls are no
more a necessary preliminary TO the
adjustment Of n receiver than violent
explosions Of days gone by are to the
starting Of the present-day motor cars.
The ability to get distant stations
and pick up programs from one cod
Of the country to another ia another
requirement that must be met by the
modern receiver. Fans are no longer
thrilled to hear music broadcast from
station 10 or 20 miles away. They
are not satisfied unless they can span
the continent and reach across the
ocean.
Must BE Simple to Tune.
With all these qualities. simplicity
of design and ease of control must
not be sacrificed. A multiplicity of
tuning controls may be desirable from
the standpoint of the individual who
likes TO play with them, but they are
certainly not desirable to those who
look upon the radio programs as a
means Of entertainment. A good re
ceiver must be simple to tune and
stable in adjustment. Stability in ad-
justment not only refers to the ability
of a circuit to stay put" after il has
been adjusted to a station; it also
means the characteristic Of "A receiver
which makes it possible to get the
same results. day after day and night
after night, without any display of
temperament"
Selectivity. the ability to separate
stations and cut through locals, and
sensitivfty. the ability to get distant
stations. are best obtained through the
use of several stages Of tuned radio
| frequency amplifcation.
Ordinary radio frequency ampli.ica-
ton. however, has certain inherent
disadvantages. which must be elimi-
mated before an efficient receiver can
he obtained. One of these is the off.
ffculty experienced in adjusting the
! receiver to the best point OF operation
over the whole wave-length range.
Another Is the tendency Of the cir.
cults to go into oscillation and cause
the production of whistles and howls.
Still another Is the difficulty in getting
good tone quality when several stages
Of tuned radio frequency are used,
and last, but not least, is the multi.
plicity Of controls usually necessary TO
provide the tuning adjustments IN
such receivers
The manner in which these disad
vantages have been eliminated nd
turned to good advantage in the BIT
counterphase circuit will be discussed
tomorrow.