Unit 5 — Calibration and Verification

TM-GEAR-007 — Open Handout TM Chapters: Chapter 6, Chapter 7 ELOs: Calibrate the COMMON-MODE CHOKES — RFI SUPPRESSION ON FEEDLINES; verify performance against acceptance criteria; complete calibration log Estimated time: 45 minutes (actual lab work required)

Step 1: Read the TM

Open TM-GEAR-007. Read Chapter 6 — Calibration and Chapter 7 — Verification and Acceptance completely.

Then come back here.

Chapter 6 — Calibration Content

1. Measure choking impedance |Z_choke| with a NanoVNA: connect port 1 to the coax shield at one end; port 2 to the coax shield at the other end (center conductor floating). Measure |Z| across the band.
2. Target: |Z_choke| ≥2000Ω at all frequencies in the operating range. For type #31 stacked pair: Z should exceed 5000Ω from 7–30 MHz.
3. Verify that differential-mode insertion loss is −0.1 dB at all HF frequencies.

Chapter 7 — Verification Content

1. Z_choke ≥2000Ω at all operating frequencies.
2. Differential-mode insertion loss <0.1 dB.
3. After installation: receive noise floor on the antenna must not increase (some CMC failure modes add noise; verify with SDR noise scan before/after).
4. Log: date, core type, design (toroid/bead/sleeve/ugly), measured Z_choke at 7 and 14 MHz, differential insertion loss, operator.

Calibration vs. Verification — Distinction

Calibration (Chapter 6): active adjustments to bring the component within specification. You are permitted to adjust, tweak, and repeat until the criterion is met.

Verification (Chapter 7): independent confirmation that the calibration succeeded. No adjustments are permitted during verification. If a verification check fails, you return to Chapter 6, not to Chapter 7.

Acceptance Criterion

A criterion found in Chapter 6: 0.1 dB. Confirm the exact criterion in the TM.

Write the exact criterion from the TM here before you start the lab:

Lab Checklist

Work through each item in sequence. Do not skip steps.

• [ ] All required equipment gathered and ready
• [ ] Equipment warmed up per TM requirements
• [ ] All Chapter 4 setup steps verified complete
• [ ] Chapter 6 calibration performed (all steps)
• [ ] Calibration criterion met (recorded below)
• [ ] Chapter 7 verification performed (all steps, no adjustments)
• [ ] All verification criteria passed
• [ ] Calibration log entry completed

Calibration Log Entry

• [ ] Date
• [ ] Equipment used
• [ ] Measurements taken
• [ ] Results vs. criteria
• [ ] Operator name

Record your results:

Self-Check Questions

SC5-1. What is the acceptance criterion for this calibration (from Chapter 7)?

SC5-2. During verification, one reading fails. What is the correct action per the TM?

SC5-3. List the items required in a calibration log entry per Chapter 7.

SC5-4. What is the difference between calibration and verification in this context?

SC5-5. If the component passes all Chapter 7 checks, what does that tell you about its current state?

Answer Key

SC5-1. See Chapter 7. The criterion is stated as a specific value with units.

SC5-2. Stop verification. Return to Chapter 6 and re-calibrate. Diagnose the cause before re-adjusting.

SC5-3. See Chapter 7, last numbered step. The log items are listed there.

SC5-4. Calibration allows adjustments; verification does not. Verification is independent confirmation.

SC5-5. It tells you the component is performing within its specified parameters at this time. It does not tell you how long it will remain in calibration — periodic re-verification is required.

Checkpoint

You are ready for the final assessment when you can: - [ ] State the acceptance criterion from memory - [ ] State the difference between calibration and verification - [ ] State the required log items from memory

→ Proceed to Final Assessment