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......
b.
Set the
SELECTOR switch at
the
SWEEP position.
2.
Perforrn
steps
2.
through
7
of
the broadband
calibration
procedure
given
f
o
r
ope
ra ti
on in the
X
band.
These instru
c
tions n1ay be found
under
Calibration
{100%
Reflection,
Broadband}.
above.
Controls on
the Model 670HM
and the Model
67
OSM
are similar
in designation
and
function.
Beam Voltage and
Current, Model670
SHF
Oscillators
~-
Beam
Beam (Cathode)
Model
Volts
Current
67
0H
J.
, .
000
20 ma.
670HM
1,0
00
20 ma.
I
670S
80
0
-
900
14
-
16 ma.
670SM
800
-
900
14
-
16 rna.
Factors Which Affect
Accur
acy
of
Refl~ctometer
M_easurements --
G
e
ne
ra
l
-
In any measu
re
rnent systern operated at
micro
wave
frequencies
,
there
are a
number
of places w
he
re err
ors
may
be introduced into the
system.
Differences
in character
i
stics
b
e
t
w
ee
n
co
rresponding
components
i
n
the
incident
and reflected
c
h
a
nne
l
s
,
l
oss
e
s
, a
nd
spur
i
ous signals all contribute to
po
ss
i
ble
inaccuracy of the
ratio
indi
c
ate
d
by
the
M
odel
416A meter.
In
practice
, probable
er
ror generally i
s
not a total of
th
ese
possible
er-
rors because
all
e
rro
r
s
a
r
e
no
t
in
th
e
same direction and are
independent,
and,
therefore, the probability
of
err
o
rs
canceling
is
large.
However, in
a
ny
m
icr
o-
-
wave
measure1nent system some
er
ror
will
be present.
The essence
of
good practic
e
in
using any systern is to ernploy
te chn
iques
(and utili
ze
available
acces
so
rie
s
)
to
n1inin1ize
o
r
remove the
effec
t
of
the
error
inherent
in the
system.
F
o
r tuna
t
eLy
t
he
reflec
to
rneter
l
ends itse
lf
admirab
ly
t:o
techniques
w
hich
minimize
er2r
ors considei·ably.
The
SET
TO FULL SCALE
control
on the
Mode
l
4
1
6.A
,
f
o
r
exan1ple,
provides a
me
a
ns by
w
hich loss
e
s
i
n
the system may be overc
ome in
general at the tirne
of
calibration,
by
i
ns
erLon
o
f
sufficie
nt
:::;
aini
.c
~:_::.e
::ceflec
t
e
d
cha
nnel
to
bring the reflecte
d v
o
l
tag
e
up to th
e
level
it
would
h
ave in
a l
oss
le
ss
syste
rn.
Anoth
er
technique
that rnay be us
e
d
,
which
includes
the use of
a
vailab
le
a
u
xilia
ry equipment
(a
slide
scre
w tune
r
a
nd
moving
loa
d)
,
v..rill
canc
el
out th
e
e
rror
signal which is due
to
finite
d
i
rectivity
oi
the
re
fl
ected
d
irecL
on
;;i_
;_
c
oup-e
r.
·r
h
e
s
e
a
nd
other
a
pp
li
ca
b
l
e
techni
ques h
ave
been :ind icat
ed
as p
e rt:me
nt
t
h
r
oughout the ope
rabng
inst
r
uctions.
T
he
rnagnitude
of
e
~r.ror
in
the
syste
rn
,
as indicated
i
n Fig.
10,
is
r-
e -
l
a
ted
to
the rn
E .gni
tude
o:t
th
e
reflE:
:
c
t
i
on
co·~
ffi
c
i
ent
and
i
s
much
_e
s s
w
hen
n1eas
-
uring reflection
coeffi cie
nts
of
a
l
ow magnitude than when
me
a
suring high
re
-
fle ction
coefficients.
-
Z9-
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