Bird Model 43 Wattmeter
13
4. Compare the attenuation with published data for line type and
length (remember to halve N
db
or double the line length to account
for the measurement technique).
Note:
This measurement should be supplemented by either
time domain reflectometry or DC continuity and leakage
checks, since the attenuation measurement alone cannot
account for faults such as open or short circuits partway down
the line.
Note:
Tery small attenuations require allowance for normal
instrument errors. Make sure to note exact readings, or their dif-
ference, on the initial equality check, and correct for this.
Frequency Response
Bird Plug-In Elements have a flat frequency response over their speci-
fied operating range. A sample set of curves is shown in Figure 6.
Notice that for the low power element, the rolloff outside its frequency
band is more pronounced than for the high power elements.
Example -
At 40 MHz the 10C element will have a loss of 4 dB,
giving a reading of about 40% of the true value For the 100C,
the loss will only be about 1 dB, for a reading at 80% of the true
value, and the 500C should be within the normal 5% of full
scale tolerance.
Содержание Thruline 43
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