Instrument Description
Coaxial RF Power Standards Instruction and Service Manual
1-7
Coaxial RF Power Standards with an “A” & “B” Suffix in the Model
Number
Some of these Coaxial RF Power Standards have a model number with “No” letter suffix at the
end and some have an “A” or “B” suffix. There is no fit, form, or function difference between the
“A” versions and the “No” letter suffix. On the “B” version the internal workings and external
electrical connections are identical and the case is the only difference. Therefore, the information
contained in this manual applies to all three. If in the text of this manual a model number is used
without the letter suffix, the information also applies to the same model with a letter “A” and “B”
suffix.
It was discovered that a small amount of the RF signal could leak through the thermistor mounts
into the DC Substitution circuit (see Chapter IV Theory of Operation). This leakage only occurs at
specific frequencies (100 kHz for the F&M1125 and F&M1130 and 10 MHz for the F&M1135) and
could cause errors in the DC substitution measurement (typically less than 1%). In order to
reduce this leakage, a common mode choke was added in the models with an “A” and “B” suffix.
An external common mode choke assembly (P/N 1000027) can be used with models without the
“A” or “B” suffix to reduce the RF leakage. Contact TEGAM for more information
.
Additional Equipment
Table 1.5 lists the additional equipment required to operate RF Power Standards. The description
for each piece of equipment listed states the minimum recommended requirements for that piece
of equipment. There may be many models that meet the minimum requirements; it is up to the
operator to select the specific model. Measurement uncertainty will vary depending on the
additional equipment used. Please refer to the specifications for the particular model number to
get that information.
Table 1.5 Additional Equipment Required
RF Level Controller
TEGAM Model 1805B
Type IV Power Meter
1806 (A), 1804/1820
DVM
DC Volts, 6½-digit minimum resolution.
Power meter
1830A
Applications
The TEGAM RF Power Transfer Standards are an element of a system and are not “stand-alone”
instruments. The TEGAM RF Power Transfer Standards are designed to be employed as the fourth
arm of a bridge configuration. This unit is designed as the sensing element in RF power calibration
and measurement systems.
Figure 1.4 shows a power sensor calibration setup using a TEGAM Model 1805B RF Level
Controller and a Working RF Power Standard to form a Precision Power Source to perform power
sensor calibrations at 1 to 10 mW (0 to +10 dBm).
Figure 1.5 shows a Terminating RF Power Standard being used to measure the power of a 50 MHz
reference output on a power meter. The Terminating RF Power Standard can be used in many
applications requiring direct measurement of RF power.
Figure 1.6 shows the calibration of a Working RF Power Standard using a Reference RF Power
Standard. The Reference RF Power Standard can be calibrated by TEGAM or a national standards
agency, such as NIST, and that calibration can be transferred to a Working RF Power Standard.
