Unit 2 — Equipment and Test Setup
TM-CAL-014 — Open Handout TM Chapter: Chapter 3 ELOs: Identify required equipment; understand test configuration Estimated time: 20 minutes
Step 1: Read the TM
Open TM-CAL-014. Read Chapter 3 — Materials and Construction completely.
Then come back here.
Chapter 3 Content
3-1. DRY LOAD (UP TO 25 W)
| Qty | Item | Specification |
|---|---|---|
| 10 | Non-inductive resistor | 500 Ω 5 W each, carbon film or metal oxide |
| 1 | BNC or PL-259 chassis connector | For RF connection |
| 1 | Copper-clad PCB or ground plane | For resistor mounting |
| 1 | Aluminum enclosure | With ventilation or heatsink |
3-2. CONSTRUCTION NOTES
Ten 500 Ω resistors in parallel = 50 Ω total. Each carries 1/10 of total power. For 25 W load, each resistor handles 2.5 W (rated 5 W). Mount resistors radially from center BNC connector with leads NOTE: Carbon composition resistors have good non-inductance but poor power stability. Metal oxide film is preferred: non-inductive and stable. Avoid wirewound at RF frequencies due to inductance.
Equipment Readiness
Review the equipment list in Chapter 3 carefully.
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 reference 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