TELE-TECH & - AmericanRadioHistory.Com

CUES for BROADCASTERS
Practical ways of improving station operation and efficiency
4 GANG
ROTARY SWITCH
e
Ilp
I 73 -
110 V.
(FOR AEU
USED FIOR PILOT CN ÚTS
TO INDICATE SPEED
45 MOTOR
4
*AUTOMATIC
SWITCM
MANUAL
Ly110V. FROM SWITCH
(33-76) ON 64-A TT.
110V
3- position, 4 -gang rotary switch chooses
speed and correct pickup simultaneously
Converting Electrically
Switched Turntables To 45 RPM
GEORGE ROUNTREE, Ch. Engr.
KVLH, Pauls Valley, Okla.
PROVIDING for 45 rpm records
has been a problem for many
small stations, and possibly some
are still using a sort of haywire
setup. KVLH has Presto 64 A
turntables. Converting such turntables
to three -speed is expensive,
since separate electrically -switched
motors must be used for each speed.
The problem was solved at
KVLH, and the present means
seems handier than the usual three -
speed tables methods. The station
has always started the 64 A's with
6 v. relays operated by spare contacts
on the console turntable
switches, and has used one pick -up
to play records, another for transcriptions.
Both the Prestos and
45's ($17.50 RCA's) are now started
with the same relay, and use one
3- position rotary switch to choose
the speed and pickup. The three
motors are connected through a
section of the switch one in. or so
from the pick -up section to prevent
hum. There are times when a different
pick -up speed combination is
desired. A 3 - pole double - throw
switch gives the choice of auto-
i
matie operation, with the motors
being connected at the same time as
the pick -ups, or manual operation,
with all three motors being turned
on with their individual switches.
One transformer for matching both
45 and 33 pick -up to console is used.
If separate transformers are used
on input, two sections of the rotary
switch may be skipped and console
input connected at points A and B.
Battery Powered
Remote Amplifiers
EDGAR T. CARTER, Studio Engr.
KUJ, Walla Walla, Wash.
APIECE of remote equipment
which "hews to the line," and
is designed to serve as a pre- amplifier
capable of delivering an adequate
voice -quality signal to the
control room from a remote point,
works with a minimum of trouble,
weighs only about a lb., and costs
less than $20.
The entire equipment is mounted
in a utility box measuring 4 x 5 x 6
in. in which the A and B batteries
take up half the space. Binding
posts on the front panel provide
connections to a telephone line or
other gear such as a recorder or
P.A. amplifier. The front panel
headphone jack serves two purposes,
providing both an "off-on"
switch and a means of monitoring
the outgoing program. With this
arrangement the equipment turns
on automatically when the headphones
are plugged in. A crystal
microphone is used. The micro-
XTAL
MICROPHONE
R1
12 MEG
149 1.2 MEG
R3..5 MEG
phone jack is the RCA type commonly
found on much home equipment.
Perhaps a loop of the microphone
cord around the carrying
handle is a wise precaution when
the equipment is in use.
For long broadcasts, such as ball
games, larger batteries with greater
capacity should be used; but for
an ordinary "man on the street,"
store opening, or spot news broadcast,
the small size Burgess N6 and
2F are adequate.
The circuit shown is self- explanatory,
being simple and straightforward.
The pad is for 10db,
smoothing the bumps in the output
somewhat. The output transformer
was found in the "surplus" market.
Converting Tape Machines
to Half Track Playbcch
GLEN .SOUTH WORTH
Moscow, Idaho
WITH the increasing number of
home type tape machines in
the public's hands, it may be very
worthwhile occasionally to have a
means of playing back "homemade"
tapes on dual track machines.
A very inexpensive, temporary
conversion can be made of the Magnecord
tape equipment by slipping
out the normal single track pole
piece from the playback head and
replacing it with a half track Pen -
tron pole piece, costing approximately
$2.00.
As only half the width of the
(Continued on page 154)
Pre -amp is turned on automatically when the headphones are plugged in
CI
lu4
R4 I MEG C1 = .005
R5R6R7R8.130 OHMS C2=.03
R9. 350 OHMS C3..01
R4
_ 4 BIAS
- +CELAS
3V4
ort2
"A" I 112
VOLTS_ T
OFF-ON SWITCH
(PART OF PHONE JACK)
T-
VOLTS
"B" B
BURGESATTERY S
N6
"A" BATTERY
BURGESS 2F
UT
PHONES
112
Tele -Tech & ELECTRONIC INDUSTRIES June 1956