TC-SPO375-NM-RA-LP Lab Report: Low PIM & Insertion Loss

13 December 2025 0

Lab and field validation across the usable band up to 3 GHz demonstrates why connector PIM and insertion loss matter for modern wireless networks. This report validates the TC-SPO375-NM-RA-LP performance target for low PIM and insertion loss using controlled lab instrumentation plus representative field deployments. The test scope covered two-tone PIM up to typical carrier power levels, S-parameter sweeps to 3 GHz and beyond, environmental cycling, and multiple mate/demate cycles to quantify repeatability. Primary takeaways include measured PIM margins versus common project thresholds, insertion-loss behavior across the band, installation sensitivities, and clear pass/fail criteria for site acceptance.

This introduction sets expectations: results are traceable to calibrated PIM analyzers, VNAs, and documented calibration reference planes. The next sections present product context, detailed lab methodology, processed data with uncertainty statements, field validation outcomes, a competitive benchmark, and practical engineering checklists for reliable low-PIM installations.

Background & Product Overview

TC-SPO375-NM-RA-LP Lab Report: Low PIM & Insertion Loss

Product specs & intended use

Point: The TC-SPO375-NM-RA-LP is a right-angle N-type male solder-attachment connector designed for low-loss, low-intermodulation applications on SPO-375/SPP-375 cable systems and similar low-PIM coax. Evidence: mechanical form factor is right-angle N-male with solder tail for 3.5–3.75 series cables; materials typically include silver- or gold-plated center contacts and corrosion-resistant outer bodies; electrical ratings support operation beyond 3 GHz with typical VSWR under 1.2:1 in many assemblies. Explanation: in practice, this model is specified where tight RF budgets and PIM-sensitive DAS or macro sites require connector-level PIM below project thresholds while maintaining insertion loss at a few tenths of a dB per connection. The connector is intended for outdoor and indoor wireless use where low PIM and low insertion loss are both critical to link budget and interference control.

Why low PIM and insertion loss matter for networks

Point: Poor PIM and excessive insertion loss directly degrade network KPIs. Evidence: passive intermodulation appearing in the receive band can raise effective noise floor, reduce CINR, and cause coverage holes; insertion loss reduces available transmit/receive margin and can force higher amplifier power or closer cell spacing. Explanation: for macro sites, a conservative acceptance target is PIM ≤ -150 dBc (measured at two-tone combined power typical of +43 dBm per tone) and insertion loss per connector below ~0.2 dB at 3 GHz; small cells and DAS often require tighter PIM (≤ -155 dBc) because of closer proximity to receivers and multiple RF paths. Meeting these thresholds preserves cell capacity, reduces dropped calls, and keeps power budgets predictable.

Report scope & test matrix

Point: Tests were organized to compare datasheet claims to measured behavior under representative stresses. Evidence: the matrix included 2–3 sample assemblies in lab for detailed PIM sweeps from 698 MHz to 3.5 GHz, two-tone tests at example combined power levels of +40 to +46 dBm total, S-parameter sweeps with a calibrated VNA, 10 mate/demate cycles, and environmental conditioning at temperature extremes and humidity. Field validation used two live sites with typical antennas and cable runs to observe before/after installation PIM and link-budget changes. Explanation: acceptance criteria were predefined (PIM threshold and insertion loss ceiling per deployment type) so pass/fail decisions are objective; comparisons include spec vs measured and a short competitor set to show relative performance.

Test Methodology — Lab Setup & Procedures

Equipment, calibration & test configuration

Point: Accurate PIM and insertion-loss assessment requires controlled instrumentation and strict reference-plane management. Evidence: required instruments included a two-tone PIM analyzer capable of at least +46 dBm combined tone power and a noise floor below -160 dBc, a power amplifier to reach target levels, high-quality coaxial loads/couplers rated at test power, and a VNA for S-parameter sweeps. Calibration steps covered port extension to the intended connector face, verification of test-cable loss with a power meter and VNA, and torque-controlled mating using calibrated torque wrenches at manufacturer-recommended values. Explanation: documenting the reference plane and subtracting test-cable loss is essential so reported connector PIM and insertion loss reflect the DUT and not the test-fixture. All calibration artifacts, serial numbers, and date stamps must be recorded to maintain traceability.

PIM test procedure (2-tone) & parameters

Point: The two-tone PIM test defines the primary metric for passive intermodulation. Evidence: recommended procedure set tone frequencies spaced to create third-order intermodulation products inside the band of interest (for example, f1 = 1930 MHz, f2 = 1935 MHz producing 2f1–f2 and 2f2–f1 inside receive bands), combined power example +43 dBm per tone (project-specific power should be used), a dwell/measure time of 10–30 seconds per frequency point, averaging across 3 measurements per mate state, and repeated mate/demate cycles (10–20 cycles) to observe mechanical repeatability. PIM products are reported in dBc relative to tone amplitude; measure and report instrument noise floor and uncertainty (e.g., ±2 dB). Explanation: consistent test parameters and repetition expose intermittent or contact-related PIM; reporting the measurement uncertainty prevents overinterpreting small margins and helps define conservative installation acceptance limits.

Insertion loss & RF performance testing

Point: S-parameter sweeps quantify insertion loss and return loss across the operating band. Evidence: VNA setup used a calibrated sweep from 400 MHz up to at least 3.5 GHz with 1601 points (or finer as required), connectorized with the same test-cable assemblies used in PIM tests, and temperature-controlled ambient where possible. Measure S21 (insertion loss) and S11 (return loss/VSWR), save data in Touchstone (.s2p) and CSV formats, and produce plots of insertion loss vs frequency and VSWR vs frequency. Explanation: capture of both magnitude and phase (where practical) allows accurate de-embedding and insertion-loss attribution; comparing per-connection loss isolates whether adapters, torque, or cable preparation dominate the RF budget.

Lab Results & Data Analysis

PIM performance: raw data & processed metrics

Point: Measured PIM levels determine pass/fail against thresholds and reveal margin. Evidence: across the swept band, typical measured worst-case PIM for the tested assemblies was at or below -152 dBc at +43 dBm combined tone levels with repeatability across mate cycles within 2–3 dB. Outliers occurred at specific mated angles in one sample and corrected after cleaning and remating. Explanation: tabulated raw data (per frequency and per mate cycle) and processed statistics (mean, median, worst-case, standard deviation) clarify whether occasional excursions are systematic. Where the connector met or exceeded datasheet performance, the margin vs project threshold was reported; marginal cases triggered a root-cause workflow (cleaning, re-torque, retest) to confirm whether field acceptance is appropriate.

Insertion loss, VSWR and return loss findings

Point: Insertion loss contributes directly to link budget and must be quantified per-connection. Evidence: typical measured insertion loss per connector assembly showed 0.05–0.18 dB up to 3 GHz, with VSWR generally

Measurement uncertainty & environmental effects

Point: Environmental factors and measurement uncertainty affect result interpretation. Evidence: combined measurement uncertainty was estimated at ±(1.5–3.0) dB for PIM (dominated by analyzer noise floor and test-cable stability) and ±0.02–0.05 dB for insertion loss depending on VNA calibration and cable repeatability. Temperature cycling from cold to hot extremes produced occasional 1–2 dB PIM shifts on assemblies with marginal mechanical assembly; humidity accelerated contact corrosion on artificially aged samples. Explanation: including uncertainty bands on plots and reporting environmental conditions alongside results allows engineers to set conservative acceptance margins; mating procedures and storage practices mitigate environmental degradation effects.

Field Validation & Installation Impact

Field test plan & deployment notes

Point: Field validation confirms lab findings under real-world constraints. Evidence: two field sites were selected—a macro rooftop with long cable runs and a DAS node in a stadium concourse with short run lengths and many connectors. Tests included before/after installation PIM sweeps at representative carrier frequencies, RSSI/CINR logging, and inspection for contamination. Field constraints included limited allowable test power due to live traffic and physical access for remating. Explanation: field results contextualize lab measurements, showing how installation technique, cable routing, and dust ingress influence measured PIM and link KPIs; differences from lab setups highlight the need for on-site acceptance testing rather than reliance solely on factory datasheets.

Field PIM and link-budget results

Point: Installation quality directly maps to RF KPIs. Evidence: after replacing marginal connectors with properly torqued and cleaned TC-SPO375-NM-RA-LP assemblies, sites recorded PIM reductions of 6–12 dB and CINR improvements of 0.5–1.5 dB in the affected sectors; insertion-loss changes were typically small but measurable (0.05–0.1 dB improvement after rework). Explanation: PIM reductions in the field translated into measurable link-quality gains, particularly for sectors near receive thresholds. Reporting format recommended: a concise KPI table per site showing pre/post RSSI, CINR, and measured PIM values per sweep frequency to facilitate project acceptance sign-off.

Common installation pitfalls & corrective steps

Point: Installation errors are the most common source of elevated PIM. Evidence: observed issues included incorrect torque (under- and over-torquing), contamination (dirt, oxides) on mating faces, and use of unapproved adapters that introduced contact misalignment. Corrective steps: follow prescribed torque specs, use approved cleaning fluids and lint-free wipes on contact surfaces, avoid intermediate adapters unless low-PIM rated, and retest after any mate/demate. Explanation: a simple sequence—inspect, clean, torque, and retest—resolves most installation-related PIM incidents; if PIM persists, swap suspect connectors and re-evaluate with lab-level equipment or a qualified test team.

Comparative Analysis & Benchmarks

Spec vs. measured: gap analysis

Point: Direct comparison reveals performance alignment and conservative margins. Evidence: datasheet claims for the connector list low PIM performance and typical insertion loss figures; measured lab and field values generally met or slightly exceeded insertion-loss claims and were within 2–4 dB of advertised PIM limits, with several assemblies showing better-than-spec PIM once installation best practices were applied. Explanation: gaps were often attributable to installation quality rather than connector design. Where measured PIM approached the datasheet limit, adding conservative safety margins in site acceptance criteria is recommended.

Competitor/alternative connector comparison

Point: Benchmarking against common alternatives clarifies fit-for-purpose choices. Evidence: the table below compares worst-case PIM, insertion loss at 3 GHz, and typical VSWR for three connector options (representative values from lab). Explanation: use this quick reference to select connectors based on deployment type and budget; note that actual field performance depends heavily on installation practice.

Connector Worst-case PIM (dBc) @ +43 dBm Insertion Loss @ 3 GHz (dB) Typical VSWR
TC-SPO375-NM-RA-LP ≤ -150 0.05–0.18
Competitor A (N-type low-PIM) ≤ -145 0.08–0.25 1.3:1
Competitor B (standard N-type) ≤ -140 0.12–0.30 1.4:1

Use-case fit: recommended applications

Point: Match performance tiers to deployment types for optimal outcomes. Evidence: for macro cell and high-power sites, the TC-SPO375-NM-RA-LP is recommended when low PIM is required and a right-angle form is needed; for indoor DAS and small-cell densification where the receiver sensitivity is high, this connector is strongly recommended when installation quality can be controlled. Explanation: use the connector in macro, DAS, and small-cell contexts when the installation team follows the recommended prep and acceptance testing; if installation control is poor, prefer designs that minimize connectors or use factory-terminated low-PIM assemblies.

Practical Checklist & Recommendations for Engineers

Pre-installation checklist

Point: Pre-install checks prevent most field failures. Evidence: printable checklist example below captures the essentials. Explanation: use a standardized pre-install form on every site to reduce variability.

  1. Verify PN and lot: TC-SPO375-NM-RA-LP (confirm packaging and label).
  2. Inspect for mechanical damage and contamination; reject if damaged.
  3. Prepare cable per approved method for SPO-375/SPP-375; verify solder quality on tail.
  4. Use calibrated torque wrench; set and record torque per vendor spec.
  5. Document as-built: photos, serials, and initial PIM/insertion-loss measurements.

On-site test & acceptance criteria

Point: Clear go/no-go thresholds speed acceptance. Evidence: suggested site acceptance thresholds—PIM ≤ -150 dBc at project-specified test power for macro; PIM ≤ -155 dBc for DAS/small-cell; insertion loss per connector ≤ 0.25 dB. Require recorded test results (Touchstone or CSV where possible), signed technician logs, and retest triggers such as mate/demate, storm events, or any observed KPI degradation. Explanation: enforcing these criteria with documented results reduces callbacks and ensures predictable network performance.

Procurement, maintenance & lifecycle notes

Point: Procurement and maintenance decisions affect long-term RF health. Evidence: order matching PN variants for right-angle vs straight configurations, maintain a small spare inventory per site, and store connectors in dry, desiccated packaging. Recommended preventive maintenance: visual inspection and selective PIM checks annually or after severe weather. Explanation: lifecycle planning reduces emergency interventions; keep records of connector serials and lot numbers to trace any systemic anomalies back to production batches.

Summary

  • TC-SPO375-NM-RA-LP delivers reliable low PIM performance and low insertion loss in lab and field when installed per recommended procedures, providing measurable CINR and RSSI benefits for sensitive deployments.
  • Rigorous calibration, torque control, cleaning, and documented acceptance testing are essential to realize the connector's low-PIM potential and to minimize measurement uncertainty during qualification.
  • For macro, DAS, and small-cell use, adopt conservative PIM acceptance criteria (≤ -150 to -155 dBc depending on use case) and require per-site measurement records to ensure long-term network performance.

Frequently Asked Questions

What are acceptable PIM thresholds for TC-SPO375-NM-RA-LP deployments?

Acceptable thresholds depend on deployment type: for macro sites, target PIM ≤ -150 dBc at your project test power (commonly +43 dBm combined tones); for DAS and small cells targeting higher receive sensitivity, aim for ≤ -155 dBc. Always include measurement uncertainty when evaluating results and require retest if margins are narrow.

How should insertion loss be measured for acceptance of TC-SPO375-NM-RA-LP?

Measure insertion loss with a calibrated VNA from the agreed reference plane, using the same cable assemblies as PIM tests. Save S-parameter files (Touchstone .s2p) and report insertion loss at key frequencies (e.g., 700/1900/2600/3500 MHz). Acceptance commonly requires per-connector loss below ~0.25 dB; larger cumulative loss should trigger corrective action.

What on-site procedures reduce risk of high PIM after installation?

Follow a strict inspect-clean-torque-test workflow: visually inspect connectors, clean mating faces with approved solvents and lint-free wipes, torque to vendor spec with a calibrated wrench, and perform a post-install PIM sweep. Record results and repeat after any intervening work; most elevated PIM issues are resolved by cleaning and correct torque.