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Model P-20B

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12 GHz RF Probe

DESCRIPTION

The P-20B 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-20B makes it possible to conveniently and accurately monitor or inject signals up to 12 GHz into RF circuits without significantly loading or detuning them. The P-20B comes with Interchangeable Ground Clips that adapt to a wide range of applications.

THEORY OF OPERATION

A frequency compensated 450 ohm resistive element is utilized in the probe’s design to reduce circuit loading and to give the P-20B a 10:1 VOLTAGE RATIO when connected to a 50 ohm instrument and probing a 50 ohm source. Special construction techniques of the P-20B produce low stray capacitance to minimize the capacitive loading effects on RF circuits.

RF instruments require low inductance grounding to make consistent and accurate measurements. TheP-20B’s Interchangeable Ground Clips provide low inductance grounding and the ability to make contact with the circuit’s 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.

RF GROUNDING

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

Measurements from 100 kHz to 12 GHz can be accurately measured by directly grounding the P-20B’s grounding barrel or by using the Short Ground clip.

The Long Ground clip is very versatile and adapts to a wide range of circuits bur SHOULD NOT be used if RF frequencies are above 1 GHz.

See TYPICAL P-20B PR0BE RESPONSE for more details located in next section.

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 probe. To minimize inductance, it’s better to make
direct contact with the grounding barrel of the probe.

CAUTION !

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

TYPICAL P-20B RF PROBE RESPONSE

RF VOLTAGE MEASUREMENTS

RF Voltage Measurements from 100 kHz to 12 GHz can be made at 7 Volts RMS
continuously or up to 35 Volts RMS for one second.

The P-20B 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-20A’s 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 )

RF POWER MEASUREMENTS

RF Power Measurements from 100 kHz to 12 GHz can be made up to +30 dBm
( 1.0 watt ) continuously or +44 dBm ( 25 watts ) for one second.

The P-20B 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 instrument’s 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.

Whn an RF source needs to be measured accurately refer to the "corrective Factor for Loading Effects" Chart directly below if the chart source has an impedance of 50 0hms.

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

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

RF SIGNAL INJECTION

The P-20B RF probe is a PASSIVE device with a built in DC BLOCK 50V MAX.

This means that the P-20B RF probe can be used to inject RF signals.

PERFORMANCE VERIFICATION

   The performance of the P-20B 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 typically be a 6 dB increase in the generator’s output VOLTAGE.

   Measurements of a 50 ohm RF output terminated only with the P-20B will typically appear to have a +5.2 dB increase in POWER. This is due to the light loading characteristics of the P-20b 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-20B 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.

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

SPECIFICATIONS

FREQUENCY RESPONSE:               100 kHz to 12 GHz
                                                                          Typically <  +/- 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
                                                               SMA 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.

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.