High-power RF amplifier temperature monitoring proves effective

German company, BONN Elektronik is a designer and manufacturer of RF power and microwave systems with a reputation for exceptional quality and reliability. The company produces standard and customised power amplifiers using solid state, TWT and pulsed amplifier technologies for communications applications that span low frequency subsea to broadband, GPS and satellite - with frequency ranges from the low kHz up to 50 GHz, and power ratings from a few Watts to over 30kW.

Especially at very high power levels, maintaining amplifier temperature and heating levels is a critical part of the amplifier´s monitoring system - ensuring reliability and preventatively maintaining the long service life required for BONN Elektronik´s customer-oriented specifications.

Convenient mounting for the probe is an important consideration and the Variohm ETP-RT ring terminal mounted temperature probe perfectly suits the open chassis design of these power stages. In addition the ring terminal design lends itself to straightforward adaptation for EMC shielding in the very direct vicinity of the potentially high levels of electromagnetic radiation from the power amplifier module.

Variohm adds EMC shielding to the temperature sensor and wiring by adding a coaxial screened cable which is extended circumferentially over and around the encapsulated sensor element and soldered to the actual ring terminal which is then bolted to the chassis´ earth, The complete assembly is then insulated and protected with heat-shrink sleeving.

The Variohm ETP series probes are part of a range available as ring terminal, hexagonal bolt, and PTFE, stainless steel or brass tube designs. They are all available as PTC and NTC versions with a wide selection of standard options for general industrial or scientific precision temperature measurement applications.

They are designed for convenient mounting and precision temperature measurement performance in applications from HVAC to industrial or scientific processes. All the various ETP designs include IP67 sealed thermistors with improved encapsulation techniques for best thermal conductivity to ensure fast response times.

The typical temperature range is -40 to 125°C for the 10K3A1B version and -40 to 250°C for the PT version. As illustrated by this application, they are also available as custom modified temperature probes with higher temperature ranges, modified mounting, connection options and electrical characteristics.