The Communications & Arts Laboratory in Belconnen carried out a performance evaluation of a Teko/Telecom RP44R5, 5 Watt UHF-UHF Television Translator. The National Transmission Agency had requested the testing of this Translator.

The test equipment used to test the Translator, a Teko Model RP44R5, Serial Number 62159 and prepare this report is as follows:

· Spectrum Analyser Rohde & Schwarz FSAC

· Plotter Hewlett-Packard 7470A

· Video Measurement Set Tektronix VM700A

· PAL Insertion Generator Tektronix VITS 201

· RF Signal Generator Rohde & Schwarz SMH

· Video Test Generator Rohde & Schwarz SPF2

· TV Test Transmitter Rohde & Schwarz SBUF/SBTF2

· RF/Video Mixer Rohde & Schwarz MUF2-Z2

The Teko 5 Watt Television Translator, Model RP44R5 submitted for inspection appears well made and its modular construction allows easy access to all modules for repair or replacement.

There is however an additional step required to remove the power supply, Downconvertor and Upconvertor modules. To remove the Up-convertor and Downconvertor modules from the unit, it is necessary to disconnect the four SMB connectors on the back of the module. This requires removal of the top panel of the translator to gain access to these connectors and to unplug them.

To remove the power supply module, in addition to removing the top panel of the translator to disconnect the DC leads running to other parts of the circuit. It is also necessary to remove a screw on the right hand side of the translator case to slide out the power supply module.

Electrically the translator seems well designed and constructed. Good quality components appear to have been throughout the equipment. The provision of RF test-points on each of the modules should make locating a faulty module a lot easier.

Changing the input and output frequencies of the translator is relatively easy. Firstly set the new receive and transmit local oscillator frequencies by adjusting the front panel thumb-wheel switches. Secondly remove and tune the input and output filter modules to the new receive and transmit frequencies. It is necessary to remove the filters and tune them on the bench using a network analyser or similar. This completes the necessary adjustments for a frequency change.

The Technical Handbook supplied with this translator would be adequate for the purpose of repairing and maintaining the equipment.

The next page shows the front and rear panel layout of the Translator, courtesy of the Teko Technical handbook.

A 19" RACK-MOUNTING CASE, 3 UNITS HIGH

B&E UHF INPUT/OUTPUT FILTER MODULE

C UHF-IF DOWNCONVERTOR MODULE

D IF-UHF UPCONVERTOR MODULE

F POWER SUPPLY MODULE

G 2 WATT UHF AMPLIFIER MODULE

H 5 WATT UHF AMPLIFIER MODULE

The Appendix of this report contains the test results:

The VM700A Test Report, Appendix A, shows the "back-to-back" measurements for the test modulator and demodulator only, for comparison with the Translator test results.

In Appendix B, is shown the VM700A Test Report results for tests carried out on the Teko Translator.

Results shown in the Appendixes:

· The second harmonic performance of the Translator is displayed in Appendix C. The level of harmonics at twice vision carrier frequency is almost 65dB below that of the vision carrier.

· The adjacent channel performance is shown in Appendix D. The level of unwanted signal at vision carrier minus 5.5 Mhz is approximately 60dB below the level of the vision carrier.

· Appendixes E to O, display various tests carried out using the VM700A. All the tests demonstrate satisfactory performance specifications except for the Group Delay & Gain (Appendix F) and Chrom/Lum Gain Delay (Appendix M). However, this may be due to the TV test transmitter and receiver combination having a Group Delay problem, refer to Appendix A.

· Appendixes P to S, show the Intermodulation performance of the Translator using both three and four tones, with and without the internal linearity corrector. The intermodulation performance of the Translator easily achieves the NTA specifications with the Linearity Corrector switched in as can be seen from the plots.

· The Swept Frequency response of the Translator is displayed in Appendixes T and U. As can be seen from the plots the Translator exhibits approximately a 2dB roll-off at the lower end of channel pass-band. The NTA specification calls for a frequency response of -1dB to +0.5dB relative to Vision Carrier. Therefore the Translator frequency response is marginally outside the NTA specification but a simple re-alignment of the Downconvertor should rectify this problem.

· The Manufacturer’s specifications are given in Appendixes V and W.

Overall, the Teko 5 Watt Television Translator is considered to be an acceptable unit with some reservations about its frequency response and the need to remove the top cover to replace some of the modules.

To its credit, the design of the Teko makes it a reasonably simple exercise to change the input and output frequencies of the Translator for use on other channels.