Element Design Factors in Moderate Wave Broadcasting
Technical staff need to know appropriate design factors to apply in selecting components for broadcast RF systems. When there are no set in place standards in this area, there are general industry best practices in place at many companies that contain worked for a long time. high frequency capacitor
All of the antenna system aspect computations are based on RMS Carrier voltage and current. These computations are adjusted for modulation highs and related to the specific labeling system used on mica and vacuum pressure capacitors, which are different! A mica capacitor (292, G3, etc. ) with a voltage rating of 20 KV is about corresponding to a rating of 35 KV in a vacuum capacitor. Current evaluations do not require such an adjustment.
Vacuum Capacitors margin is based off Peak Test Volts Score.
(Built-in 40% Safety Element to Peak Modulation)
Briciola Capacitor margin is established off Peak Working V Rating.
(Built-in 40% Basic safety Factor to Peak Modulation)
Capacitors & Inductors perimeter relies off RMS Recent Ratings.
(Built-in 20% Security Factor to Average Modulation)
Be aware that these ratings are based on safety factors appropriate to a design based on “solid” details. In the absence of design limits, if guidelines (i. e. – antenna impedance, and so on ) are estimated or uncertain, higher design factors must be applied, which are an issue of engineering judgment. However, lower design factors may be justified where special concerns of component cooling, location or procedure prevail.
The industry preferred practice in this case is to use the above factors at the worst-case design operating values representing the bounds of the eq and impedances for which the equipment is made. This kind of practice will usually bring about even more conservative design factors nearby the center of the designed range. Yet , in simple low ability systems, increasing the above values 10 – 15% and applying that to the estimated antenna impedance may be satisfactory to accommodate variations encountered in the field.
When systems are designed based after estimated data, it is critical to verify the adequacy of component selection by measurement or calculations based on measured guidelines before applying rated system power!
Bear in head that components shared with multiple frequencies, such as in filters for diplexers or triplexers, have a special set of guidelines. Basically, voltages add vectorially, and currents add on an RSS basis. Analysis of the circuits is best left to the experienced RF design engineer.