TELE-TECH & - AmericanRadioHistory.Com

=
Why HARTFORD
are
specified
in
AIRCRAFT RADIO CORPORATION'S
R -30 ADF RECEIVER
The Hartford Pyrex Glass Balls you see
in the capacitor assembly gang diagram have
important multiple functions that could provide
the answers to similar problems with your
product. Hartford Pyrex Balls are specified for
the following reasons -
Dielectric constant of 4.9 at 60 cycles
Ability to withstand shock
Surface smoothness of balls within 8.0,tc
In. R.M.S. important to both mechanical
and electrical operation
Dimensional uniformity of balls within
.0005" important to critical air space in
function of receiver
Coefficient of thermal expansion of
0.00000184 In./In./°F
If your product requires precision balls, retainers,
or bearings made to your specifications
- consult Hartford Engineers - and
specify Hartford qualify.
-- `4 szvr -tford
PRECISION BALLS
BEARINGS
HARTFORD STEEL BALL CO., INC.
23 Jefferson Avenue, \Vest Hartford 6, Connecticut
rg {
is
r -t- jx. The actual input power
Verr
(rg +r)2 +x2
The assumed input power is
vez
(2)
(3)
4 re
The experimentally measured variation
of input impedance with frequency
of junction transistors of
either grounded -base or grounded
emitter with a resistive load shows a
phase angle which attains a maximum
value about 50 °. Hence for
junction transistors the observed
maximum value of X relative to r
will be about L2 r, or
X2 = L44 r° (4)
Let re = I z; ß/r2
I
+ x2 = 1.56 r (5)
The actual input power will then be
Vet r Vet V5'
(6)
6.55 r' +1.44r 2 7.99 r 5.13 r,
The possible error is about
A G, = - 1.08 db or less
Therefore, under worst conditions,
the input power is 1.08 db or less
than the assumed value.
3. The error introduced due to the
discontinuity of rg can be studied by
investigating the largest possible
percentage deviation of the input
impedance value from rg. It is clear
that the largest percentage deviation
will occur when the input switch is
in position 1 or 2 and when the input
impedance is 75 ohms. The deviation
will be 33.3 %. The actual input
power will be:
V5' 1.333 V52
(7)
(1 + 1.333)2ra 4.1 ra
Therefore the possible error in this
case is
AG,= -0.11db
The actual input power is 0.11 db
less than the assumed value.
4. The error due to change of r1,
in steps is important at low frequency
because at these frequencies
the output impedance of a junction
transistor is fairly large. If the output
impedance is larger than the
range of resistance provided in this
equipment, then the error can be
fairly high. However if the output
impedance is within the resistance
range provided, the maximum possible
error will be, the same as for
case 3, that is,
Ga=- 0.11db
when switch 2 is at position 1 or 2.
Under this condition, the output
power is 0.11 db less than the actual
value.
(Continued on page 358)
When You Buy a "Do -It- Yourself"
Speaker Enclosure Kit
Your speaker enclosure is not just a box. Its
an important component of your Hi -Fi system.
A "build -it- yourself" enclosure should be as
good as the finest factory- assembled enclosure.
When you "build your own" don't end up with
a cheesebox ... make sure that the kit you buy
has all these features:
1. Select 3/4" Hardwood Cabinet Plywood
Heavy -!a" thick v, 00(1 uxd throu__h,rul. Principal
sections of enclosure arc of Select Grade
Birch. Same quality a, tt ed in finest furniture.
2. All Wood Pre -Shaped
Providing locked and mitred joints for extreme
rigidity and buzz -free performance. Almost all
assembly donc with a screwdriver.
3. Speaker Mounting Board Flexibility
Interchangeable adapter boards for countless
P.S.E. combinations of multispeaker systems
with provision for future speaker expansion.
4. "Decor-Coustic" Design
A perfect union of the most advanced principles
of acoustic baffling and interior decoration. No
screws or other hardware visible on surface of
enclosure. Self -contained...functions independently
of walls and floors. Truly ... a cornerlesscorner
enclosure.
Only University "KwiKits" have all these important
features. Don't forget, the difference
between mediocre kits and the finest is only
a matter of a few dollars. Don't jeopardize the
quality of your whole system by a false economy.
sca.0
Model KEN- 15- Similar to EN enclosure
series In every respect except that -Kul-
Kit" employa simplified front frame design.
Unique mounting board is pre -cut
for 15" speakers and supplied with adapter
for 12" speakers. Abo for most of the popular
2 or 3 way P.S.E. Speaker Systems.
nclosure complete: 37" H, 28" W, 19r4"
D. Model KEN- 15-Net Price $49.75.
Model KENl2- Similar to Model KEN -
15 except that mounting board Is pre -cut
for all 12" speakers. Alm for most of the
popular 2 or 3 way P.S.E. combinations.
Completed enclosure measures 30" II x
21/2" W x 15 %" D. Model KEN -12-
Net Price $39.75.
(Instruction manual supplied
free with each kit)
If you're interested in a lifetime of musical enjeymeni.
learn more about magnificent University "KwiKits."
O) -1
LOUDSPEAKERS, INC.
80 So. Kensico Ave. White Plains, N.Y. Desk 1115
Please send me valuable "KwiKit" information.
Name
Address
City Zone State
Tele -Tech & ELECTRONIC INDUSTRIES June 1956
For product information, use inquiry card on pages 209 -210. 357