Calculate Vpk and Irms for given power at complex load
Calculator input form
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
- 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
- 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 Guanella 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
The load impedance or admittance may be found by measurement or predicted
using models or tools such as
Results are returned in a separate window. Each instance of the
uses its own output window, so different scenarios can be explored in
browser instances of the calculator and they will return results in
results windows. The "New results window for each calc" switch on the
calculator form will force new results into a new results window. If
calculator window is refreshed, results will be written to a new
V1.01. Use at your own risk, not warranted for
purpose. Do not depend on any results without independent verification.
Owen Duffy 1995, 2016. All rights reserved. Disclaimer.