Unit 4 — Operating Procedures and Calculations
TM-TOOL-007 — Open Handout TM Chapters: Chapter 5, Appendix A ELOs: Execute operating procedure; interpret readings; compute derived quantities Estimated time: 30 minutes (includes 3–4 practice problems)
Step 1: Read the TM
Open TM-TOOL-007. Read Chapter 5 — Operating Procedures and Appendix A completely.
Then come back here.
Chapter 5 Content
- Connect transmitter to IN (N-type), antenna (or dummy load) to OUT. Select HF or VHF/UHF section. Select power range (start at highest range and reduce until needle is >30% FSD).
- Key transmitter. CYD displays forward power (W), reflected power (W), and SWR in real time. Update rate: 10 Hz.
- For digital modes (FT8, WSPR): set display to AVERAGE mode (5-second rolling average) to see mean power through the duty cycle.
- At end of session: record peak power, SWR, and band in operating log.
Appendix A — Reference Formulas
| SWR | |Γ| | Return Loss (dB) | % Power Reflected |
|---|---|---|---|
| 1.0:1 | 0.000 | ∞ | 0% |
| 1.5:1 | 0.200 | 14 dB | 4% |
| 2.0:1 | 0.333 | 9.5 dB | 11% |
| 3.0:1 | 0.500 | 6 dB | 25% |
| 5.0:1 | 0.667 | 3.5 dB | 44% |
Key Formulas Summary
Key mathematical relationships from Appendix A:
(See Appendix A in the TM)
Operating Notes
Chapter 5 specifies 4 operating steps.
Measurement discipline: - Always warm up the tool and reference sources before taking readings - Multiple readings improve accuracy — use 3–5 readings and average them - Record every reading with frequency, power level, and settings - A result that seems wrong almost always means a setup error, not a failed tool
Practice Problems
Work these before reading the answer key below.
P4-1. Using the operating procedure from Chapter 5 and the formulas from Appendix A: State the measurement steps you would take to characterize a 40m (7.150 MHz) dipole antenna using the COMPACT PORTABLE RF POWER METER. List steps in order.
P4-2. From Chapter 5: what measurement setting or configuration produces the most accurate result with the COMPACT PORTABLE RF POWER METER? What is the tradeoff if you use a less accurate setting?
P4-3. Chapter 5 specifies an operating procedure for a specific measurement scenario. State the first three steps of that procedure from memory.
P4-4. Appendix A gives a formula for computing a result from measured values. Pick one formula and compute a worked example using made-up but realistic values. Show all work.
Answer Key — Practice Problems
P4-1. Compare your list to Chapter 5. Steps should include: select range/mode → connect antenna → apply signal or enable source → adjust for null/maximum → read and record → compute result.
P4-2. See Chapter 5. The most accurate setting is usually the narrowest bandwidth or highest resolution, at the cost of longer measurement time or reduced range.
P4-3. See Chapter 5, steps 1–3. Copy exactly then close the TM and state from memory.
P4-4. See Appendix A for the formula. Your arithmetic is correct if your result has the right units and is physically plausible.
Checkpoint
Before proceeding: - [ ] You can state the operating procedure from memory (at least the first 5 steps) - [ ] You can compute the derived quantity from Chapter 5 / Appendix A without looking - [ ] You understand what "an unexpected result" tells you about setup
→ Proceed to Unit 5