Unit 4 — Operating Procedures and Calculations

TM-GEAR-009 — Open Handout TM Chapters: Chapter 5, Appendix A ELOs: Install and operate the RF HYBRID COUPLERS — QUADRATURE, WILKINSON, AND RAT-RACE correctly; interpret performance data; compute derived quantities Estimated time: 30 minutes (includes 3–4 practice problems)

Step 1: Read the TM

Open TM-GEAR-009. Read Chapter 5 — Operating Procedures and Appendix A completely.

Then come back here.

Chapter 5 Content

5-1 Circular Polarization Feed

1. Connect the transceiver to Port 1 (input) of the branch-line hybrid. Connect a horizontally polarized element to Port 2 (0°) and a vertically polarized element to Port 3 (−90°).
2. Port 4 (isolated) is terminated in a 50Ω load — do not leave it open; it must be terminated for correct operation.
3. Result: the two antenna elements receive equal power with 90° phase offset, producing circular polarization.

Appendix A — Reference Formulas

Key Formulas Summary

Key mathematical relationships from Appendix A:

(See Appendix A in the TM)

Operating Notes

Chapter 5 specifies 3 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 RF HYBRID COUPLERS — QUADRATURE, WILKINSON, AND RAT-RACE 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 RF HYBRID COUPLERS — QUADRATURE, WILKINSON, AND RAT-RACE? 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