Unit 4 — Operating Procedures and Calculations
TM-TOOL-010 — 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-010. Read Chapter 5 — Operating Procedures and Appendix A completely.
Then come back here.
Chapter 5 Content
- Select HF or VHF section switch. Select power range (start high; reduce until FWD needle is at 50–80% FSD for best accuracy).
- Connect transmitter to IN (SO-239 or N-type); antenna to OUT.
- Key transmitter briefly (1–2 seconds). Read FWD and REF needles.
- Compute SWR: set the FWD meter scale to its reference mark; read SWR directly from the ratio scale, or compute from the formula in §2-3.
- For antenna tuning: adjust tuner while watching REF needle. Minimum REF deflection = maximum power transfer = lowest SWR.
Appendix A — Reference Formulas
| Core | Material | Al (nH/turn²) | Best range |
|---|---|---|---|
| BN-43-202 | #43 ferrite | 189 | 1.8–50 MHz |
| FT-50-43 | #43 ferrite | 523 | 1.8–50 MHz (higher impedance) |
| FT-50-61 | #61 ferrite | 69 | 10–200 MHz |
| FT-50-67 | #67 ferrite | 40 | 50–500 MHz |
Key Formulas Summary
Key mathematical relationships from Appendix A:
(See Appendix A in the TM)
Operating Notes
Chapter 5 specifies 5 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 SWR METER — CONSTRUCTION AND USE. List steps in order.
P4-2. From Chapter 5: what measurement setting or configuration produces the most accurate result with the SWR METER — CONSTRUCTION AND USE? 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