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Model 435 Β
2. MATH
A
SS UMPTI ONS:
ADJUSTMENTS
5-6.
P
O WER REFEREN C E OSCI LLATO R LEVEL ADJU ST MENT (Cont'd)
TYPICAL
1. ACC U RA C Y
CALCULATIONS:
DVM M easurements:
(HP 3455Α -90
d
ays, 23°C ±5°C)
Math Assumptions:
±0.01%ο
EFFE CTIVE EFFICIENCY
C
AL (NBS):
±0.5% ο
MISMATCH UNCERTAINTY :
(Source & Mount SWR <_1.05)
±0.1%ο
<±ρ .7%ο
ΡRF =
2Vc οΜΡ (V 1- μο) + V ο 2- μ 1 2
(4R) (EFFECTIVE EFFI CIENCY)
Assume: V ο 2- μ 1 2=-( μ 1 - μο)2
S in ce: -(V 1 -V ο ) 2 = V1 2 +2V1Vο -Vο 2, and
we wa n t: Vο 2 - V 1 2, then
t
heerroris: (- V 1 2 +2V , V ο - Vο 2)-(Vο 2 - V 1 2 )=-2Vο 2 +2V ,V ο =2Vο(V1 -Vο)
if 2 Vο (V 1- Vο) < < 2μCΟΜΡ (V1 - Vο)
i .e.,
Vο < < V c οΜΡ, error is
n
eg ligible
VcοΜΡ - 4
v
olts. If Vο < 400 μ V, er r or is <0.01%ο.
(typi cally Vo can
b
e set to <50 μV.)
3. Derivation
o
f Formula for V1- Vο
ΡRF =
2 VςΟ ΜΡ (V1- Vο)+ Vο 2- μl2
(4R) (EFFECTIVE EFFI CIENCY)
Desired Ρ RF = 1 MW =10-3
:.1ρ -3 = 2μςΟΜΡ (μ1-
μ o) + μο 2-- μ l2
(4R) (EFFECTIVE EFFI CIENCY)
(V comp)
±0.018% ο
(V 1 - V o)
±0.023% ο
(R)
±0.03%ο
Adjustm e n ts
L
et (4R) (EFFECTIVE EFFICIEN C Y) (10 -3) = Κ
S
ubstitute - (V1 - V ο)2 for Vo 2 - V 1 2 (see math A ssumptions under Accur acy)
Then 0 = (V1- Vο) 2 -2V ςοΜΡ (Vi - Vο)+ Κ
o
r V 1 - Vο = Vc οΜΡ -
(
μ c οΜΡ) 2- Κ
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