Calculate Vpk and Irms for given power at complex load

Calculator input form

Power (W):
Load:
Title:
No symbols in output:
New results window for each calc:

SVN:

Overview

This calculator computes the peak voltage and RMS current a the load specified given the specified continuous power level.

The peak voltage is useful in rating the voltage withstand of components. Voltage breakdown happens in an instant, so components need to withstand the peak voltage presented. Some notes:

Transmitters are often capable of higher peak envelope power than might be indicated by a 'key down carrier' test for several reasons. Unless the PEP has been measured, it is wise to allow 20% higher than continuous carrier.

Even though a PA may be operated at less than its maximum rating (eg a 2500W capable PA operated at 1500W), a conservative position is that an amplifier may produce transients up to its rated output power.

Heating of conductors is due to the longer term RMS current. Some notes:

This calculator gives the RMS for the specified power level.

Power loss in conductors is due to I^2R, and the R of conductors and components at RF is usually much higher than at DC due to skin effect, and the current carrying capacity of conductors is reduced from their DC rating.

Though effective R is higher, longer term heating of conductors is ameliorated by the low duty cycle of some modes (eg SSB telephony).

Some components (eg current balun cores) are not heated by the differential current calculated above, but by the common mode component of current which, although proportional to differential current in a given scenario, may range from much lower to much higher than differential current.

The load impedance or admittance may be found by measurement or predicted using models or tools such as TLLC .

Results window

Results are returned in a separate window. Each instance of the calculator uses its own output window, so different scenarios can be explored in separate browser instances of the calculator and they will return results in separate results windows. The "New results window for each calc" switch on the calculator form will force new results into a new results window. If the calculator window is refreshed, results will be written to a new results window.

V1.01. Use at your own risk, not warranted for any purpose. Do not depend on any results without independent verification.