Product Information Page

Description

Theory of Operation

RF Grounding

Typical P-20A RF probe response

RF Voltage measurements

RF Power measurements

Correction factor for loading effects

Power level conversion

RF Signal injection

Performance verification

Cross reference level chart

Specifications

Limited warranty

Auburn Technology  
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DESCRIPTION

 

DESCRIPTION


   The P-20A is a PASSIVE 10:1 RF VOLTAGE RF PROBE with a 50 Volt  DC BLOCK built in. It has been designed to allow users of RF test equipment to use standard signal tracing techniques. The P-20A makes it possible to conveniently and accurately monitor or inject signals up to 3 GHz into RF circuits without significantly loading or detuning them. The P-20A comes with Interchangeable Ground Clips that adapt to a wide range of applications.

 

 

 

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THEORY OF OPERATION

 

THEORY OF OPERATION


   A frequency compensated 450 ohm resistive element is utilized in the RF probeís
design to reduce circuit loading and to give the P-20A a 10:1 VOLTAGE RATIO when connected to a 50 ohm instrument and probing a 50 ohm source. Special construction techniques of the P-20A produce less than 1 pf of stray capacitance at 1 Mhz to minimize the capacitive loading affects on RF circuits. RF instruments require low inductance grounding to make consistent and accurate measurements. TheP-20Aís Interchangeable Ground Clips provide low inductance grounding and the ability to make contact with the circuitís active RF ground. To prevent false readings or damage to test equipment, an internal DC blocking capacitor ( 50 volts MAX. ) is provided to decouple in-circuit supply voltages.

   

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RF GROUNDING

 

RF GROUNDING


   To obtain consistent and accurate RF amplitude measurements PROPER  
 RF grounding
is 
REQUIRED

    Measurements from 100 kHz to 1 GHz can be accurately measured by directly grounding the P-20Aís grounding barrel or by using the short pin or flexible ground clip. Frequencies from 1 to 2 GHz will require  direct grounding of the P-20Aís grounding barrel or the use of the short pin ground clip. Frequencies from 2 to 3 GHz will require direct grounding of the P-20Aís grounding barrel. See Typical P-20A RF probe response for more information.

   Ground clips can be changed by grasping the ring portion of the clip and twisting it,
while pulling to remove or pushing to assemble. Moderate force may be required.

   If a good RF ground is out of reach, a 6 inch metal ruler or similar item can often be 
used to extend the ground to the RF probe. To minimize inductance, itís better to make 
direct contact with the grounding barrel of the RF probe. 

    Verification of a low inductance RF ground can be accomplished by slightly changing the P-20A ground contact position  while observing that there are no significant changes in readings.

CAUTION ! 

The P-20Aís grounding barrel is a low impedance ground. 
   Avoid Contact with Supply Voltages and Personal 
Contact if 50 Volts or Higher are present !

 

 

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TYPICAL P-20A PROBE RESPONSE

 

TYPICAL P-20A RF PROBE RESPONSE

 

              DIRECT BARREL GROUNDING RESPONSE

 

 

                       SHORT PIN GND CLIP RESPONSE

 

 

FLEXIBLE GND CLIP RESPONSE

 

 

 

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RF VOLTAGE MEASUREMENTS

 

RF VOLTAGE MEASUREMENTS


   RF Voltage Measurements from 100 kHz to 3 GHz can be made at 7 Volts RMS 
continuously or up to 35 Volts RMS for one second.

     The P-20A produces a 10:1 VOLTAGE RATIO when used with instruments, 
such as RF Volt Meters and RF Detectors while probing a 50 ohm source. 
RF circuits commonly have or nearly have a 50 ohm impedance and because of this, measurement errors will typically be insignificant for standard signal tracing techniques.

   Accurate RF Voltage Measurements can be obtained by MULTIPLYING the 
instrument's reading by 10.05. ( The .05 is the correction factor for the P-20Aís loading 
characteristics for a 50 ohm source. )  


    When a source with an impedance other than 50 ohms needs to be accurately 
measured, use the following equation to obtain the correction factor.

TRUE VOLTAGE = ( MEASURED V * 10 ) * L RATIO

  L RATIO = 1 + ( CIRCUIT IMPEDANCE / 1000 )

 

 

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RF POWER MEASUREMENTS

 

RF POWER MEASUREMENTS


   RF Power Measurements from 100 kHz to 3 GHz can be made up to +30 dBm 
( 1.0 watt ) continuously or +44 dBm ( 25 watts ) for one second.

   The P-20A when used with a Spectrum Analyzer or RF Power Meter can effectively
 make in-circuit RF Power Measurements with out the need for Complex Calculations.  ADD +20 dB to the instrumentís reading if in dBm or MULTIPLY by 100 if using Watts 
to get the Power Measurement for a 50 ohm source. RF circuits commonly have or 
nearly have a 50 ohm impedance and because of this, measurement errors will typically 
be insignificant for standard signal tracing techniques.

   Pulse Power Measurements up to +56 dBm ( 400 Watts ) can be made, provided the 
average power level is less than +30 dBm and the Pulse Duration is less than 100
ĶS.

WARNING!

   An external attenuator should be used between the RF probe and the instrument to prevent the possibility of instrument damage due to excessive peak power. An external DC BLOCK with a adequate voltage rating is also between the RF probe and attenuator to prevent possible damage to measurement equipment if voltages greater than 50 volts are present.

   When an RF source needs to be measured accurately refer to the "Correction Factor for
Loading Effects" chart and the "Power Level Conversion" chart if the source has a 
impedance other than 50 ohms.

 

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CORRECTION FACTOR FOR LOADING EFFECTS

 

CORRECTION FACTOR FOR LOADING EFFECTS

 

 

Circuit Impedance in OHMS:   Readings in WATTS  MULTIPLY BY:  Readings in dBm  ADD:
 25  1.05     .21
50 1.10    .42
75   1.16 .63
100  1.21   .83
200  1.44    1.58
 500   2.24   3.52
  1000 4.00   6.00

 

To calculate loading effects for other impedances:

VOLTAGE RATIO = 1 + ( IMPEDANCE / 1000 )

POWER RATIO = VOLTAGE RATIO SQUARED

 

 

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POWER LEVEL CONVERSION 

 

POWER LEVEL CONVERSION 

 
Circuit Impedance in OHMS   Readings in WATTS Readings  in dBm
2 25.0 14.0
5 10.0 10.0
10 5.0 7.0
20 2.5 4.0
25 2.0 3.0
50 1.0 0.0
75 .67  -1.8
100 .50  -3.0
200 .25  -6.0

 

 

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RF SIGNAL INJECTION

 

RF SIGNAL INJECTION

  

   The P-20A RF probe is a PASSIVE device. This means that RF signals can flow through 
the RF probe in either direction. Because of this characteristic and the P-20A’s 500 ohm 
impedance, RF signals can be injected with out excessively loading the circuit being 
tested or the signal source.

   The INSERTION LOSS of the P-20A RF probe is approximately 20 dB when connected 
to a 50 ohm source and injecting the signal into a 50 ohm circuit.

   NOTE!   The Insertion Loss will change depending on the impedance of the circuit 
being injected.


 

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PERFORMANCE VERIFICATION 

 

PERFORMANCE VERIFICATION


  
The performance of the P-20A can be verified by removing the ground clip and properly
 probing the output of a known RF source such as a RF Signal Generator.

   PLEASE NOTE!   RF Signal Generators are designed and calibrated to drive a 50 ohm 
load. If the generator’s output is not terminated there will be a 6 dB increase in the 
generator’s output VOLTAGE.

   Measurements of a 50 ohm RF output terminated only with the P-20A will appear to have a +5.2 dB increase in POWER. This is due to the light loading characteristics of 
the P-20A RF probe, resulting in a measured INSERTION LOSS of 14.8 dB instead of the 
normal 20 dB.

   Normalization of frequency response errors when using the P-20A RF probe with a spectrum analyzer and tracking generator can be done the same way as the above verification. Be aware that frequency response ripple is a function of the RF probe and analyzer input impedance, and will be constant as long as the analyzer input attenuator is not changed. Be sure and allow for the +5.2 dB error if the signal source is NOT  terminated into 50 ohms. If the signal source IS terminated into 50 ohms, the measurement error is due to the P-20A -.2 dB loading.

 

 

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CROSS REFERENCE LEVEL CHART

 

CROSS REFERENCE LEVEL CHART


dBm   VOLTS   POWER
+ 30 7.07 V 1.00 W
+ 29 6.30 V  794 mW
+ 28 5.62 V  631 mW
+ 27 5.01 V 501 mW
+ 26 4.46 V 398 mW
+ 25 3.98 V  316 mW
+ 24 3.54 V 251 mW
+ 23  3.16 V 200 mW
+ 22 2.82 V  158 mW
+ 21 2.51 V 126 mW
+ 20  2.24 V  100 mW
+ 19  1.99 V 79.4 mW
+ 18  1.78 V  63.1 mW
+ 17 1.58 V  50.1 mW
+ 16  1.41 V  39.8 mW
+ 15  1.26 V 31.6 mW
+ 14 1.12 V  25.1 mW
+ 13  999 mV 20.0 mW
+ 12 890 mV 15.8 mW
+ 11 793 mV 12.6 mW
+ 10  707 mV 10.0 mW
+ 9  630 mV  7.94 mW
+ 8 562 mV 6.31 mW
+ 7 501 mV 5.01 mW
+ 6  446 mV 3.98 mW
+ 5 398 mV  3.16 mW
+ 4  354 mV 2.51 mW
+ 3  316 mV 2.00 mW
+ 2 282 mV 1.58 mW
+ 1 251 mV  1.26 mW
0 224 mV 1.00 mW
- 1  199 mV  .794 mW
- 2 178 mV  .631 mW
- 3 158 mV .501 mW
 - 4   141 mV .398 mW
 - 5  126 mV  316 mW
- 6  112 mV  .251 mW
 - 7  99.9 mV .200 mW
 - 8  89.0 mV  .158 mW
- 9 79.3 mV .126 mW
- 10 70.7 mV .100 mW
- 11 63.0 mV  79.4 uW
- 12 56.2 mV  63.1 uW
- 13  50.1 mV 50.1 uW
 - 14  44.6 mV 39.8 uW
 - 15 39.8 mV  31.6 uW
- 16 35.4 mV 25.1 uW
 - 17 31.6 mV 20.0 uW
- 18 28.2 mV 15.8 uW
- 19 25.1 mV  12.6 uW
- 20 22.4 mV 10.0 uW
- 21  19.9 mV 7.94 uW
- 22 17.8 mV 6.31 uW
 - 23 15.8 mV 5.01 uW
 - 24 14.1 mV 3.98 uW
- 25 12.6 mV 3.16 uW
- 26  11.2 mV 2.51 uW
- 27  9.99 mV  2.00 uW
 - 28  8.90 mV  1.58 uW
- 29 7.93 mV  1.26 uW
- 30 7.07 mV  1.00 uW
- 31 6.30 mV  .794 uW
- 32 5.62 mV .631 uW
 - 33  5.01 mV  .501 uW
 - 34 4.46 mV .398 uW
- 35 3.98 mV .316 uW
- 36  3.54 mV .251 uW
- 37  3.16 mV .200 uW
- 38 2.82 mV .158 uW
- 39 2.51 mV .126 uW
- 40 2.24 mV  .100 uW
- 41 1.99 mV  79.4 nW
- 42  1.78 mV 63.1 nW
- 43  1.58 mV  50.1 nW
- 44 1.41 mV 39.8 nW
- 45  1.26 mV 31.6 nW
- 46 1.12 mV 25.1 nW
- 47  999 uV   20.0 nW
- 48  890 uV  15.8 nW
- 49 793 uV 12.6 nW
- 50  707 uV 10.0 nW
- 51 630 uV  7.94 nW
- 52 562 uV 6.31 nW
- 53 501 uV  5.01 nW
- 54  446 uV 3.98 nW
- 55 398 uV 3.16 nW
 - 56 354 uV  2.51 nW
 - 57  316 uV  2.00 nW
- 58  282 uV 1.58 nW
- 59  251 uV 1.26 nW
- 60 224 uV  1.00 nW

                                              

 

 

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SPECIFICATIONS

 

SPECIFICATIONS

 

FREQUENCY RESPONSE:                100 kHz to 3 GHz
                                                                       +/-  3dB

VOLTAGE ATTENUATION:             10:1 ( Nominal )
                                                               For 50 Ohm sources

RF ATTENUATION:                           20 dB ( Nominal )
                                                               For 50 Ohm sources

RF LOADING EFFECTS:                   500 Ohms +/- 10%
                                                               < 1 pF at 1 Mhz

RF VOLTAGE RANGE:                     7 Vrms ( Continuous )
                                                                35 Vrms ( MAX. 1 Sec. )

DC VOLTAGE BLOCK:                     50 Volts Maximum

PROBE CABLE:                                  1 Meter in Length
                                                               BNC Connector

The continuous improvement of its products is the intent of Auburn Technology Corporation, who reserves the right to make design or specification changes without notice.

 

 

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LIMITED WARRANTY

 

LIMITED WARRANTY


   Auburn Technology Corporation, warrants this product against defects in materials 
and workmanship for a period of one year from date of purchase by the original 
consumer purchaser.

   The product shall not have been altered, repaired, or serviced by anyone other than a 
service facility authorized by Auburn Technology Corporation, or have been subject 
to accident, misuse, abuse, or operated contrary to the instructions.

   Auburn Technology Corporation, shall not be liable for direct, incidental, consequential, 
or other types of damages resulting from the use of this product. This warranty is in 
lieu of all other warranties, express or implied; including, but not limited to, the implied 
warranties of merchantability or fitness for a particular purpose. Some states do not 
permit limitation or exclusion of implied warranties; therefore, the above limitations 
and exclusions may not apply to you.

 

 

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Last modified: 05-21-2010