# Title: Picotest J2121A High Power Line Injector - 400V/20A ## Description: Professional High-Power PSRR Testing for Military and Satellite Applications The Picotest J2121A High Power Line Injector represents the pinnacle of power supply rejection ratio (PSRR) testing capability, engineered specifically for high-voltage, high-current applications in military and satellite power systems. This advanced test instrument enables engineers to inject precise modulation signals into DC power lines whilst maintaining electrical isolation and measurement accuracy across a wide frequency spectrum. How PSRR Measurement Works Power Supply Rejection Ratio testing quantifies how effectively a power supply or regulator attenuates unwanted AC signals on its input from appearing at the output. The J2121A modulates the input DC supply voltage using a network analyser source signal, creating controlled disturbances that simulate real-world noise conditions. Engineers measure both input and output signals to calculate the rejection ratio as 20×log(Vinput/Voutput). What Makes Line Injectors Essential: Unlike current probes or injection transformers, line injectors can handle significant DC currents whilst providing galvanic isolation between measurement equipment and high-voltage systems. Wiring Quick-Start J2121A connection diagram showing VNA, power supply, and DUT connections Basic PSRR Measurement Setup: Power Connections: Connect J2171A power supply to J2121A proprietary power connector Input Power: Connect DC supply positive to red banana jack (+), negative to black banana jack (-) Signal Injection: Connect VNA source output to BNC modulation input DUT Connection: Connect J2121A output banana jacks to device under test input Current Monitoring: Connect current monitor BNC output to VNA channel 1 Voltage Measurement: Connect high-impedance probe to DUT output for VNA channel 2 Connection Point Connector Type Function DC Input +/- 4mm Banana Jacks (Female) 400VDC @ 20A Maximum Modulation Input 50Ω BNC 6dBm Recommended Signal Level Current Monitor BNC 100mV/A Scale Factor Power Input Proprietary (J2171A) 200mA Low-Noise Supply DC-DC Converter Input Impedance Testing Beyond PSRR measurements, the J2121A excels at characterising DC-DC converter input impedance—a critical parameter for avoiding negative resistance instabilities in power distribution networks. The integrated current monitor eliminates the need for external current probes, streamlining the measurement process whilst maintaining accuracy. // Example calculation for input impedance Z_input = V_modulation / I_monitor // Where I_monitor = V_current_out / 100mV/A // Frequency sweep from 100Hz to 1MHz Professional Tip: Always use the included 1Ω calibration fixture to verify measurement accuracy before conducting critical tests. This ensures traceability and validates the complete measurement chain. Comparison with J2120A Line Injector The J2121A addresses applications where the popular J2120A's 50V/5A limits prove insufficient. Key advantages include 8× higher voltage capability, 4× higher current rating, active regulation maintaining constant 750mV voltage drop, and integrated Hall-effect current monitoring that eliminates external probe requirements. ## Product type: Injector ## Vendor: Picotest ## Tags: Injector, picotest-corp, Voltage Injector ## Price range: 2420.0 - 2420.0 GBP ## Link: https://thedebugstore.com/products/picotest-j2121a-line-injector ## Options - Title: Default Title ## Collections - [New Products](https://thedebugstore.com/a/llms/collections/new-products-debug-store) - [Admin: No Inventory](https://thedebugstore.com/a/llms/collections/no-inventory) - [Signal Injectors](https://thedebugstore.com/a/llms/collections/signal-injectors-catalogue) - [Voltage Injectors](https://thedebugstore.com/a/llms/collections/voltage-injectors-catalogue) - [Picotest](https://thedebugstore.com/a/llms/collections/picotest-catalogue) - [Picotest Signal Injectors](https://thedebugstore.com/a/llms/collections/picotest-signal-injectors) ## Variants - Default Title, SKU: J2121A, Available: yes, Inventory: -1 ## Metafields - badge: - widget:

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Phil.
PicoTest J2121A kit

J2121A kit comes with high CMRR psu, mains and DC power lead, and 1ohm calibration fixture.

A much more capable version than the J2120A, able to handle 400v DC at up to 20amps, so allowing testing of mains powered SMPS with included PFC converters and measurement of PSRR and input impedance.

This is an excellent and compact kit with everything needed already included so no extras to buy. The extra capacity makes direct testing of the DC portions of power systems being designed for mains power very simple and it is easy to set up and use and there is plenty of information and videos online to help. Overall, a very effective piece of kit.

Hi Phil

We are pleased you are satisfied with your choice, and thank you for leaving a review. This will bew helpful for future customers.

John Legg

- title_tag: Picotest J2121A High Power Line Injector - 400V/20A PSRR & Impedance Tester - description_tag: The Picotest J2121A High Power Line Injector enables precise PSRR, input impedance, and DC-biased inductor measurements for high-power applications up to 400V/20A. Ideal for military and satellite power systems. - manufacturer: Picotest Corp - warranty: 12 months - mpn: J2121A - backorder_label: If no stock is shown above, order now and we'll ship within 7 working days. - condition: new - custom_product: false - mpn: J2121A - google_product_category: Electronics - warranty: 12 months - brand: Picotest - target_keyword: Picotest J2121A - manufacturer: PicoTest Corp - breadcrumbs: ["gid://shopify/Collection/267180835005"] - brands: gid://shopify/Metaobject/56256102623 - customhs_code: 903090 - summary:

The Picotest J2121A High Power Line Injector enables precise power supply rejection ratio (PSRR) and input impedance measurements for high-voltage applications up to 400VDC and 20A continuous current. Designed specifically for military and satellite power systems, this advanced test instrument features regulated DC output with fixed 750mV voltage drop and integrated current monitoring for streamlined measurements.

Unlike passive injection transformers, the J2121A accommodates significant DC bias currents whilst maintaining measurement accuracy from 100Hz to 1MHz. The device includes an isolated current sense monitor output that connects directly to vector network analysers, eliminating external current probe requirements and reducing measurement uncertainty.

Complete package includes the J2171A 200mA low-noise power supply, 1Ω calibration fixture for measurement verification, and comprehensive user documentation. The fan-cooled design ensures reliable operation during extended test sessions, making it ideal for production environments and research laboratories requiring high-power PSRR characterisation.

- key_feature_1: Professional-grade line injector for PSRR and impedance measurements in high-power military and satellite applications up to 400V/20A. - key_feature_2: 400VDC/20A maximum power handling capability - key_feature_2_tooltip: {"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Supports high-voltage military and satellite bus applications up to 400 volts and 20 amperes continuous"}]}]} - key_feature_3: 100Hz to 1MHz measurement bandwidth - key_feature_3_tooltip: {"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Covers full frequency range for power supply and DC-DC converter characterisation"}]}]} - key_feature_4: Regulated 750mV voltage drop - key_feature_4_tooltip: {"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Active regulation maintains constant voltage drop regardless of load current for accurate measurements"}]}]} - key_feature_5: Integrated current monitor output - key_feature_5_tooltip: {"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Built-in Hall-effect current sensor provides 100mV/A output eliminating external current probes"}]}]} - key_feature_6: Fan-cooled thermal management - key_feature_6_tooltip: {"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Active cooling ensures stable operation during extended high-power measurements"}]}]} - key_feature_7: Complete measurement package - key_feature_7_tooltip: {"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Includes J2171A power supply, 1Ω calibration fixture, and comprehensive documentation"}]}]} - key_feature_8_tooltip: {"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Modulation signal passes through with unity gain maintaining measurement accuracy across frequency range"}]}]} - key_feature_8: Unity gain signal transfer - why_people_choose_3_title: Complete Solution - why_people_choose_2_title: Measurement Accuracy - why_people_choose_1_title: High-Power Capability - why_people_choose_1: Enables PSRR testing of military and satellite power systems beyond conventional equipment limits - why_people_choose_3: Includes power supply, calibration fixture and documentation for immediate operational capability - why_people_choose_2: Integrated current monitoring and regulated voltage drop ensure precise, repeatable results - 1571619: What is the maximum voltage and current the J2121A can handle?***SIMP***The J2121A supports up to 400VDC input voltage and 20A continuous current, making it suitable for high-power military and satellite bus applications up to 270V operational voltage. - 1571620: How does the J2121A differ from the J2120A Line Injector?***SIMP***The J2121A provides 8× higher voltage capacity (400V vs 50V), 4× higher current rating (20A vs 5A), active voltage regulation with fixed 750mV drop, and integrated current monitoring. The J2120A offers ultra-low noise for sensitive low-power applications. - 1571621: What equipment is needed to perform PSRR measurements with the J2121A?***SIMP***You need a vector network analyser or frequency response analyser, such as the Bode-100,  the included J2171A power supply, a DC voltage source for your test voltage, and the device under test. High-impedance voltage probes are recommended for output measurements. - 1571622: Can the J2121A measure DC-DC converter input impedance?***SIMP***Yes, the J2121A excels at input impedance measurements using the integrated current monitor output. This capability is essential for characterising negative resistance effects and ensuring power distribution network stability. - 1571623: What is the voltage drop through the J2121A?***SIMP***The J2121A maintains a regulated 750mV voltage drop from input to output across the full current range. This active regulation ensures measurement accuracy regardless of load conditions. - 1571624: What frequency range does the J2121A cover?***SIMP***The measurement bandwidth extends from 100Hz to 1MHz, covering the full frequency range needed for power supply PSRR characterisation and DC-DC converter analysis. - 1571625: Is calibration required before measurements?***SIMP***Use the included 1Ω calibration fixture to verify measurement accuracy. This practice ensures traceability and validates the complete measurement chain before conducting critical tests. - 1571626: Can the J2121A work with oscilloscopes for PSRR measurements?***SIMP***The current monitor output is optimised for vector network analysers and may not provide sufficient sensitivity for oscilloscope-based measurements. VNAs offer superior dynamic range and accuracy for PSRR testing. - 1571627: What safety precautions are necessary when using the J2121A?***SIMP***Always observe the 400VDC maximum rating. Ensure proper grounding, use appropriate personal protective equipment, and verify all connections before applying power. The device includes internal protection but safe operating procedures are essential. - 1571628: Does the J2121A require external cooling?***SIMP***The J2121A includes integral fan cooling for reliable high-power operation. Ensure adequate ventilation around the unit and avoid blocking cooling vents during operation. - rating: {"scale_min":"1.0","scale_max":"5.0","value":"5.0"} - rating_count: 1