Unit 2 — Equipment and Test Setup

TM-INST-007 — Open Handout TM Chapter: Chapter 3 ELOs: Identify required equipment; understand test configuration Estimated time: 20 minutes

Step 1: Read the TM

Open TM-INST-007. Read Chapter 3 — Materials and Construction completely.

Then come back here.

Chapter 3 Content

Build a 50 ohm Load

  • Use four 200 ohm, 1% resistors in parallel.
  • Solder directly inside a BNC/SMA connector shell if possible.

  • Keep leads short to reduce inductance.

            Build a Quarter-Wave Stub

  • Choose coax with known velocity factor.

  • Cut to calculated length (see Calculations).
  • Short the far end (center to shield).

  • Label the stub with its target frequency and VF.

            Optional GPS 1PPS Interface

  • GPS module with 1PPS output.

  • LED + resistor for lock indication.
  • Optional ESP32/CYD counter (see optional code example).

Equipment Readiness

Chapter 3 lists approximately 10 equipment items.

Before beginning any calibration, verify every item on the equipment list is: - Present and in working order - Within its own calibration period (do not calibrate with an uncalibrated reference) - Set up per the configuration specified in Chapter 3

The calibration quality is the ceiling on your calibration quality. A reference with unknown accuracy produces a calibration with unknown accuracy.

Self-Check Questions

SC2-1. List the three most important pieces of equipment specified in Chapter 3.

SC2-2. What reference standard(s) does the TM specify for this calibration?

SC2-3. Does Chapter 3 specify any warm-up time or settling requirement? If so, state it.

SC2-4. What is the test configuration? (How is the equipment connected or arranged?)

SC2-5. What would be the consequence of using a reference standard that is itself out of calibration?

Answer Key

SC2-1. See Chapter 3 equipment table or list. Identify the three items that appear first or are marked most critical.

SC2-2. See Chapter 3. The reference standard is the source of known-good values used to check the instrument under test.

SC2-3. See Chapter 3. Warm-up time is often specified for instruments that use oscillators or amplifiers — they need thermal stabilization before measurements are valid.

SC2-4. See Chapter 3. Describe the connection or arrangement in your own words, then verify against the TM.

SC2-5. The calibration error of the reference propagates directly into your calibration result. If the reference is 5% off and you do not know it, your calibration will also be 5% off — and you will not know that either.

Checkpoint

Before proceeding, you must be able to: - List the required equipment from memory - State the reference standard and its specified accuracy

→ Proceed to Unit 3