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omni30mmod [2017/04/29 17:11] n1ooq |
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| ===Alignment and Testing=== | ===Alignment and Testing=== | ||
| - | A general-coverage receiver with a BFO will be needed for alignment of the 9 MHz bandpass filter. Adjust the capacitor with a non-metallic tool only! A metallic tool will introduce a large amount of noise into the circuit, which will pass directly to the power amplifier. Adjust for minimum signal at 9.000 MHz. The rig may or may not need to be connected to an antenna, and may or or may not need to be transmitting (at low power) to hear the signal. This is the only alignment required. Bring up power slowly, with an eye on the SWR meter. High SWR into a resonant antenna or a tuner is an indication that the filters are not working properly and large spurs are being transmitted. | + | A general-coverage receiver with a BFO will be needed for alignment of the 9 MHz bandpass filter. Adjust the capacitor with a non-metallic tool only! A metallic tool will introduce a large amount of noise into the circuit, which will pass directly to the power amplifier. Adjust for minimum signal at 9.000 MHz. The rig may or may not need to be connected to an antenna, and may or or may not need to be transmitting (at low power) to hear the signal. This is the only alignment required. Bring up power slowly, with an eye on the SWR meter. High SWR into a resonant antenna or a tuner is an indication that the filters are not working properly and large spurs are being transmitted. With the general coverage receiver, listen to the 2nd harmonic at 2x the transmitted frequency. It will probably be audible, but should be relatively weak. |
