IV-4
Splitter/Combiner
The splitter and combiner (identical printed circuit boards) are used to split the RF signal into, and combine the
amplified RF signal out of the (2) final amplifier pallets. The microstrip designs are based on the simple isolated
Wilkinson combiner design. Flanged power resistors help ensure that any differences between the inputs or
outputs is balanced. Due to its electrical and mechanical symmetry, the Wilkinson design’s performance over
moderate bandwidths is superior to other types.
Directional Coupler
The Technalogix dual directional couplers provide DC voltages proportional to forward and reflected RF power
monitoring. These analog voltages are converted for processing using analog-to-digital converters and provide the
control system with valuable data for monitoring purposes. The directional couplers installed in the power
amplifier and filter enclosures have peak detection circuits on the forward RF power side of the coupler and
average detection circuits on the reflected RF power side of the coupler. This is to allow the end user to set
power in a manner that is more independent of modulation and closer to a true tip-of-sync meter. Hence the
readings on the displays in the power amplifier system are peak for forward and average for reflected. Output
power should be set following the operating procedure found elsewhere in this manual.
The directional coupler has a typical insertion loss of 0.5dB and its Type N connectors can handle 1,500 watts
peak. The coupler requires 5 Vdc to power the internal electronics of the coupler and is supplied from the control
printed circuit board at the front of the enclosure.
Filter
The passive bandpass filter rejects spurious and harmonic output products and passes the VHF channel RF
output. The cavity resonator uses aperture coupling and is a linear resonator design. Typical insertion loss is 0.6
dB to 1.0 dB depending on channel frequency. Average roll off is –33 dBc at a point 4.5 MHz below the peak
visual carrier frequency and –30 dBc 9.0 MHz above the peak visual carrier frequency. The filter is DC grounded
on both the input and output for additional lightning protection.
Summary of Contents for TAV-500
Page 1: ...TAV 500 POWER AMPLIFIER NEW ADVENTURES IN BROADCASTING Technalogix ...
Page 17: ...A A 1 1 TECHNALOGIX LTD 25 W VHF LO BAND DRIVER P25 VHF L R S MCDONALD 14 SEPTEMBER 2000 ...
Page 18: ...Technalogix Ltd 25 Watt High Band VHF Pallet PA25 VHF H S Kazarian November 12 2001 B B ...
Page 19: ......
Page 20: ...Technalogix Ltd 400 Watt High Band VHF Pallet P400 VHF H R S McDonald July 30 2001 B A ...
Page 49: ...Technalogix Ltd VIII 9 Location and Function of Controls and Connectors Power Supply ...