Unit 5 — Calibration and Verification

TM-GEAR-003 — Open Handout TM Chapters: Chapter 6, Chapter 7 ELOs: Calibrate the BALUNS AND UN-UNS — CURRENT AND VOLTAGE TYPES; verify performance against acceptance criteria; complete calibration log Estimated time: 45 minutes (actual lab work required)

Step 1: Read the TM

Open TM-GEAR-003. Read Chapter 6 — Calibration and Chapter 7 — Verification and Acceptance completely.

Then come back here.

Chapter 6 — Calibration Content

1. Measure impedance transformation ratio: connect a known resistive load (e.g., 200Ω for a 4:1 balun) to the balanced port; measure impedance at the unbalanced port with a NanoVNA. Target: 50Ω ±10%.
2. Measure common-mode impedance (choke action): connect NanoVNA port 1 to coax shield at input; port 2 to coax shield at output. Z_CM should exceed 2000Ω across 1.8–30 MHz for type #31 core.
3. Measure insertion loss: S21 through the balun into a matched load. Target: <0.3 dB at all HF frequencies.

Chapter 7 — Verification Content

1. Impedance ratio correct to within ±10% at center frequency.
2. Common-mode impedance ≥1000Ω at all specified frequencies.
3. Insertion loss <0.3 dB at 1.8–30 MHz.
4. SWR <1.2:1 at all test frequencies with correct load.
5. Power test: key a 100W transmitter into a dummy load through the balun for 30 seconds. No smoke, no temperature rise exceeding 40°C above ambient.
6. Log: date, design type, core material, turns, ratio test result, CM impedance, 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: 10%. 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