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2 2 2
HARTREY AYE
EVANSTON. ILL. ( 6 0 2 0 4 ) U.S.A.
HONES AND ELECTRONIC COMPONENTS
DATA
SHEET
MODELS 710A,
AREA CODE 3 1 2 / 3 2 8 - 9 0 0 0
CABLE SHUREMICRO
AND 710s "REX"
Low-Cost Crystal Microphones
General:
Model "7 10" series microphones are pres-
sure operated diaphram type c stal microphones. The
crystal used is a Bimorph, Roche
7
le salt unit. The micro-
phones have high impedance, high output, smooth re-
sponse, and a semi-directional pickup characteristic. The
Model "710" Series microphones have a sturdy dietast
case.
The models 7 10A and 7105 are suitable for place-
ment on the table top, desk top, or other flat surfaces;
they
fit
conveniently in the palm of the hand for use as
a hand microphone; the microphones are provided with
a stand adapter having a %"-27 thread which
f i t s
the
convential floor stand. The adapter attaches t o the base
of the microphone by using the #8-32 machine screw
provided. Model 710s has a built in switch t o control
the microphone circuit. Model 710A has no switch.
Each of the microphones in the "710" series is pro-
vided with a
7
foot (2.lm) single-conductor shielded
cable.
Applications:
Model "710" series microphones are
designed for voice and music reproduction and are ideal
for amateur communications, home recording on disc,
tape or wire, fixed and mobile public address systems,
call systems, language lab system and similar applica-
tions. The "710" series microphones are rugged units,
are designed for dependability and are recommended
for use where good quality i s required at low cost.
Connections:
The inner or "hot" conductor of the
cable should be connected t o the grid of the first tube in
the amplifier across a load resistance of 5 megohms. In-
put resistances as low as
I
megohm may be used
if
necec
sary, but higher values are recommended because of
better low-frequency response obtained.
The shield
should be connected t o the amplifier chassis or ground.
The shield, chassis or amplifier ground should be
securely grounded t o a water pipe or similar ground t o
prevent shock hazard during operation of the amplifying
system.
The cable may be lengthened
if
desired; low capacity
shielded microphone cable should be used for
this
purpose. Added lengths of connecting cable will be ac-
companied by a decrease in output level.
Operation:
N o polarizing voltage is required for
crystal microphones.
Crystal microphones may be seriously damaged
if
accidentally connected t o loud speaker or power supply
outlets carrying high voltage. Check your connections
carefully.
Crystal microphones should not be used or kept in
places where the temperature exceeds 125°F. They should
not be exposed t o the rays of the sun in ve
hot weather
7
for any considerable length of time -or
eft in closed
automobiles parked in the sun during hot weather, as the
temperature inside the automobile may easily build up to
over 125O and
ermanently damage the crystal.
When use cf' near a radio transmitter, use the mini-
mum length of cable consistent with placement require-
ments. Careful grounding of the cable shield is advisable.
SPECIFICATIONS
Voltage Sensitivity:
3.15
millivolts r.m.s.
p
e r
microbar a t the end of a 7-foot (2.lm) cable across
I
t o
5 megohms at 1000 c.p.s.
This is equivalent t o 50
db
below
I
volt per microbar at the terminals of the 7-foot
(2.
l
m) cable.
Length
. . . . . . .
. .
. .
.
. .
.
Width
. . .
. .
.
.
. . . .
.
. . .
Thickness (body)
. . . .
. . . .
Finish
. . . . . . .
. . . .
. . . .
.
Net Weight
(with 7' (2.lm) cable).
. .
Shipping Weight
.
.
.
. .
.
. .
Frequency Response:
60 t o 9000 c.p.s.
MODELS
710 and 7105
33% (81.8mm)
2fB
(68.3mm)
I
&
(36.5mm)
Metallic Red
'
'Ib
(340g)
1
v4
Ib. (5679)
Internal Output Impedance:
Equivalent t o a
900 micro-microfarad condenser.
Recommended Load Impedance:
1
to
6
megohmL
Guarantee:
Each microphone
is
guaranteed to be free from
electrical and mechanical defects for a period of one year from
date of shipment from the factory, provided all instructions
are
complied with fully. In case of damage, return the microphone
to
the factory for repairs. Our guarantee is voided
if
the microphone
case is opened.
License Notice:
Shure patents pending.
Copyright 1949,
Shure Brothera,
Inc.
271147 (1-67)
Printed in
U.S.A.
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