Boonton 9240 RF Voltmeter - Manual (Page 49)

Boonton 9240 Series RF Voltmeter
4.6 Temperature Effects
1. The accuracy specifications for the instrument apply over a temperature range of 0
° C to 50° C. Outside these limits,
operation of the instrument is possible, but appreciable inaccuracies can be expected; however, no permanent change in probe
characteristics will result from any reasonably high or low temperature exposure.
2. It should be noted that inaccuracies of measurement resulting from temperature effects may occur when measuring with
the probe in the vicinity of heat sources such as resistors, heat sinks and so forth.
3. When making low level measurements (below approximately 2 millivolts), it is important to make sure that the probe has
attained a uniform temperature throughout its body. A temperature gradient between the inside and outside of the probe can
generate a small thermal voltage that may add to the DC output of the detector diodes.
4.7 Hum, Noise and Spurious Pickup
When measuring low level signals, precautions should always be taken to avoid the possibility of measurement errors
resulting from hum, noise or stray RF pickup. Although all low frequency hum and noise are attenuated at the input,
unwanted high level signals could still possibly cause error. In some cases it may be necessary to provide extra shielding
around the probe connection to reduce stray pickup. Some typical sources of spurious radiation are dielectric heating units,
diathermic machines and transmitters.
4.8 Recorder Output
The DC output provided at the rear panel RECORDER connector may be used to drive an XY recorder for swept
measurements, or a strip chart recorder for monitoring applications. Refer to Section 2.3.
4.9 Correction Curve for Model 952003 50 Ohm Type N Tee Adapter
When using the optional Model 952003 Tee Adapter, the input voltage to the adapter is indicated directly on the instrument.
To obtain the correct output voltage from the adapter, subtract the correction shown in Figure 4-2 from the input voltage, in
dB, indicated on the instrument. Corrections are not required if the Model 952003 is terminated with 50
Ω .
4.10 Correction Curve for Model 952007 75 Ohm Type N Tee Adapter
When using the optional Model 952007 Tee Adapter, the input voltage to the adapter is indicated directly on the instrument.
To obtain the correct output voltage from the adapter, subtract the correction shown in Figure 4-2 from the input voltage, in
dB, indicated on the instrument. Corrections are not required if the Model 952007 is terminated with 75
Ω .
Operation
4-3