Peak amplifier for Bird 43 coupler directional wattmeter by F6DFZ

This article describes F6DFZ's implementation of a peak amplifier for use with a Bird directional coupler to measure Peak Envelope Power of SSB telephony waveforms.

Peak Envelope Power

The ITU Radio Regulations define the terms Peak Envelope Power, Mean Power and Carrier Power with regard to a radio transmitter. The terms are defined as:

Peak Envelope Power 'pX' (s1.157) means the average power supplied to the antenna transmission line by a transmitter during one radiofrequency cycle at the crest of the modulation envelope taken under normal operating conditions.
Mean Power 'pY' (s1.158) means the average power supplied to the antenna transmission line by a transmitter during an interval of time sufficiently long compared with the lowest frequency encountered in the modulation taken under normal operating conditions.
Carrier Power 'pZ' (s1.159) means the average power supplied to the antenna transmission line by a transmitter during one radio frequency cycle taken under the condition of no modulation.

Note: For use in formulae, the symbol p denotes power expressed in watts and the symbol P denotes power expressed in decibels relative to a reference level.

The advantages of a PEP measurement capability are:

convenient and accurate measurement of PEP (ITU pX) output power;
more effective monitoring of antenna system health as intermittent faults conditions will be better captured by the peak detector and result in more noticeable deflection in the reverse metering position.

Peak amplifier

Table 1: F6DFZ's meter specific circuit values
Component	Value
R1	1,800
R2	6,800
R3, R4	0
R5	1,200
R6, R7, R8	100,000
R9	120,000
VR1	22,000

This amplifier is based on Fig 2 at Peak amplifier for directional wattmeter / SWR meter with F6DFZ's values selected to suit the Bird 43 coupler element, see Table 1 above.

Fig 1: Bird coupler.

Figure 1 shows the Bird remote coupler with 43 coupler element.

Fig 2:Printed circuit board.

Figure 2 shows the printed circuit board designed and manufactured by F6DFZ.

Fig 3: PEP indicating wattmeter meter head.

Figure 3 shows the backlit meter head with PCB housed in a die cast box and custom scaled meter.

A very professional result, start to finish!

Peak amplifier for Bird 43 coupler directional wattmeter by F6DFZ

Peak Envelope Power

Peak amplifier

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