The service manual for the VHF-Wattmeter and Matching Indicator by Rohde & Schwarz covers the setup and operation of measuring forward and reflected VHF power in a coaxial line, including the use of a measurement head connected to a display unit with switching and instrument controls. It also provides troubleshooting guidance for calibration and adjustment of the reflection factor and relay control, ensuring proper integration into the automatic switching system of the associated transmitter.
Manual Overview
The service manual for the Rohde & Schwarz VHF-Wattmeter and Anpassungszeiger (Type NAK) provides comprehensive guidance on troubleshooting, diagnostics, calibration, and board-level adjustments. The manual emphasizes the importance of correctly identifying error codes and performing systematic troubleshooting to resolve issues. It includes detailed instructions for calibrating the forward and reflected power measurements using specific potentiometers (R17 for forward and R19 for reflected power). The manual outlines the use of the switch S162 for calibration, reflection, and direct measurement modes, and describes the path of measurement signals through various components. For board-level guidance, the manual details the role of Thyratron switch stages in controlling relay contacts and their integration into the transmitter’s automatic switching system. It specifies the need for a minimum burn-in time of 200 hours for Thyratron tubes to ensure stable ignition points, highlighting the importance of aging new tubes to maintain accuracy. The manual also notes that the device is maintenance-free and provides instructions for connecting the measurement head and operating the device.
Quick Issues Covered
- Diagnose VHF power reflection using error codes.
- Calibrate forward/reflected power with R17 and R19 adjustments.
- Power-up failures linked to Thyratron tube aging.
Overview
Refer to the PDF for details.
Specifications
- VHF-Wattmeter und Anpassungszeiger
- Frequenzbereich: 87.5…108 MHz
- Messbereich Vorlaufleistung: 0…12 kW
- Messbereich Rücklaufleistung grob: 0…12 kW
- Messbereich Rücklaufleistung fein: 0..01.2 kW
- Reflexionsfaktor: 0…100 %
- Benötigte Mindest-Vorlaufleistung für die Eichung der Reflexionsfaktoranzeige: 6 kW
- Fehlergrenzen der Leistungsanzeige (bei Sinusspannung): ±10% v. E.
- Fehlergrenzen der Reflexionsfaktoranzeige: ±5% v. E.
- Wellenwiderstand: 60 Ω
- Benötigte Mindestleistung für die Strahlungsüberwachung: 0.3 kW
- Reflexionsabschaltung einstellbar
- Belastbarkeit der Meldekontakte: 60 V, 0-5 A max.
- Netzanschluss: 220 V, 50 Hz/5
Controls & Indicators
Refer to the PDF for details.
Installation / Setup
Refer to the PDF for details.
Operation
Refer to the PDF for details.
Troubleshooting & Error Codes
Refer to the PDF for details.
Safety & Warnings
Refer to the PDF for details.
Download GERMAN Service manual (PDF – 3.5 MB)
Service manual for Rohde-Schwarz NAK 1/3/5/10kW VHF Wattmeter. Guide for troubleshooting and calibration. PDF size: 3.5 MB.
- Brand: Rohde-schwarz-nak-1-3-5-10kw-vhf-wattmeter-service-manual
- Model: GERMAN
- Type: Service manual
- File size: 3.5 MB
Overview
Brief overview of the product.
Specifications
- Key spec 1
- Key spec 2
Controls & Indicators
Control panel/button layout.
Installation / Setup
- Step 1…
- Step 2…
Operation
Basic usage, modes, cycles.
Troubleshooting & Error Codes
| Issue / Code | Fix |
|---|---|
| Example | How to fix… |
Safety & Warnings
- Important warning…
Downloads
Download GERMAN service manual (PDF)
Overview
The Rohde-Schwarz NAK-1-3-5-10kW VHF Wattmeter is a precision instrument designed for measuring radio frequency power output in the VHF range. It is widely used in broadcasting, telecommunications, and laboratory environments to ensure accurate power readings from transmitters and amplifiers. This service manual provides detailed instructions for maintenance, calibration, and repair of the device.
Main Features & Specifications
- Power measurement range: 1 kW, 3 kW, 5 kW, and 10 kW models available
- Frequency range: VHF band (30 MHz to 300 MHz)
- High accuracy and stability for reliable readings
- Robust construction suitable for industrial and field use
- Clear analog or digital display options depending on model
- Low insertion loss to minimize signal disturbance
- Calibration and adjustment procedures included in the manual
Basic Usage & Operation Tips
Before connecting the wattmeter, ensure the device is properly calibrated according to the manual. Connect the wattmeter in line with the transmitter output and antenna system, observing correct polarity and impedance matching. Allow the device to warm up for a few minutes to stabilize readings. Regularly check the display for consistent values and avoid sudden power surges that could damage the instrument.
Troubleshooting & Maintenance
If the wattmeter readings become erratic or inconsistent, verify all cable connections and inspect for any visible damage. Refer to the manual's troubleshooting section to diagnose common issues such as zero offset errors or display malfunctions. Periodic cleaning of connectors and internal components is recommended to maintain optimal performance. Calibration should be performed annually or after any repair work.
Safety Reminder
Always disconnect the wattmeter from the power source before performing any maintenance or repairs. Use caution when working with high power RF signals to prevent electrical shock or burns. Follow all safety guidelines outlined in the service manual and wear appropriate personal protective equipment when handling the device.