Unit 4 — Operating Procedures and Calculations
TM-GEAR-018 — Open Handout TM Chapters: Chapter 5, Appendix A ELOs: Install and operate the TRANSMATCH — PORTABLE ANTENNA TUNER correctly; interpret performance data; compute derived quantities Estimated time: 30 minutes (includes 3–4 practice problems)
Step 1: Read the TM
Open TM-GEAR-018. Read Chapter 5 — Operating Procedures and Appendix A completely.
Then come back here.
Chapter 5 Content
5-1 Initial Tuning on a New Band
- Set C1 and C2 to midscale. Set L to minimum (roller at bottom).
- Key the transmitter at 5 W (reduced power protects transistors during tuning on a badly mismatched antenna).
- Watch the SWR indicator. Adjust L for minimum reflected LED; then adjust C1 and C2 alternately for minimum reflected, returning to L adjustment if a new minimum appears.
- Iterate until reflected indicator is at minimum and forward indicator shows full power. Typical tuning time: 30–60 seconds.
- Increase to full operating power. Verify SWR indicator does not change.
5-2 Band-to-Band Switching
- Record successful L, C1, C2 positions for each band on the band card (laminated chart in the lid of the tuner).
- On band change: set L, C1, C2 to the recorded positions; tune briefly at 5W to confirm the antenna has not changed.
Appendix A — Reference Formulas
| Band | Typical C1, C2 range (pF) | Typical L range (µH) |
|---|---|---|
| 160M (1.8 MHz) | 200–365 pF | 15–28 µH |
| 80M (3.75 MHz) | 100–300 pF | 8–20 µH |
| 40M (7.15 MHz) | 50–200 pF | 4–12 µH |
| 20M (14.175 MHz) | 20–100 pF | 2–6 µH |
| 10M (28.5 MHz) | 10–50 pF | 0.5–3 µH |
Key Formulas Summary
Key mathematical relationships from Appendix A:
(See Appendix A in the TM)
Operating Notes
Chapter 5 specifies 7 operating steps.
Installation and operating discipline: - Always verify polarity and orientation before making connections — RF transformers and baluns are phase-sensitive - Route feedlines away from parallel conductors — parallel runs create mutual coupling that degrades isolation - Ground all exposed metalwork at a single chassis point — multiple grounds create loops - Record settings, frequencies, and power levels for every test — you need baseline data for comparisons
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 installation steps you would take to put the TRANSMATCH — PORTABLE ANTENNA TUNER in service on a 40m (7.150 MHz) station. List steps in order.
P4-2. From Chapter 5: what installation or setup detail produces the best RF performance with the TRANSMATCH — PORTABLE ANTENNA TUNER? What is the tradeoff if you omit or shortcut that step?
P4-3. Chapter 5 specifies an operating procedure for a specific use case. 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 mounting location → connect to feedline/antenna → verify polarity/orientation → apply power or signal → verify operation → record baseline.
P4-2. See Chapter 5. The most important installation detail is usually physical orientation, lead length, or ground bonding — the tradeoff if omitted is degraded isolation, increased SWR, or common-mode current leakage.
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 a degraded or unexpected result tells you about the installation
→ Proceed to Unit 5