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588sherwood [2007/04/10 16:36] n5na |
588sherwood [2007/04/10 16:40] n5na |
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| ^Parameter ^ Spec ^ Measured ^ | ^Parameter ^ Spec ^ Measured ^ | ||
| - | |DR3 20 kHz | 90 | 92 dB | | + | |DR3 20 kHz (dB) | 90 | 92 | |
| - | |DR3 2 kHz | 78 | 80 dB | | + | |DR3 2 kHz (dB) | 78 | 80 | |
| - | |Sensitivity, preamp off: | 0.5 | 0.45 uV | | + | |Sensitivity, preamp off: (uV) | 0.5 | 0.45 | |
| - | |Sensitivity, preamp on: | 0.18 | 0.17 uV | | + | |Sensitivity, preamp on: (uV) | 0.18 | 0.17 | |
| - | |Noise floor, preamp off: | | -130 dBm | | + | |Noise floor, preamp off: (dBm) | | -130 | |
| - | |Noise floor, preamp on: | | -140 dBm | | + | |Noise floor, preamp on: (dBm) | | -140 | |
| - | |AGC threshold, preamp off: | | 0.8 uV | | + | |AGC threshold, preamp off: (uV) | | 0.8 | |
| - | |AGC threshold, preamp on: | | 0.2 uV | | + | |AGC threshold, preamp on: (uV) | | 0.2 | |
| - | |S9 | 50 uV | 59 uV | | + | |S9 (uV) | 50 | 59 | |
| |Preamp | | 12 dB gain | | |Preamp | | 12 dB gain | | ||
| - | S meter reading does not change with preamp or attenuator setting. While | + | S meter reading does not change with preamp or attenuator setting. While this may be confusing, it is the correct way to keep the S meter calibration constant, regardless of preamp or attenuator settings. Some commercial receivers keep S meter readings constant regardless of preamp or attenuator selection, such as the Ten-Tec RX-340. |
| - | this may be confusing, it is the correct way to keep the S meter calibration | + | |
| - | constant, regardless of preamp or attenuator settings. Some commercial | + | |
| - | receivers keep S meter readings constant regardless of preamp or attenuator | + | |
| - | selection, such as the Ten-Tec RX-340. | + | |
| - | + | Phase noise measured -124 dBc @ 10 kHz, vs. spec of 125 dBc at 10 kHz, basically meeting spec. This parameter is the least accurate of my measurements, as it must be measured indirectly. IF DSP filters integrate phase noise differently than classic discrete filters. A slight change in the bandwidth compensation for dBc would resolve the 1 dB difference. | |
| - | Phase noise measured -124 dBc @ 10 kHz, vs. spec of 125 dBc at 10 kHz, | + | The only area where measured numbers are significantly different from spec is blocking. |
| - | basically meeting spec. This parameter is the least accurate of my | + | |
| - | measurements, as it must be measured indirectly. IF DSP filters integrate | + | |
| - | phase noise differently than classic discrete filters. A slight change in | + | |
| - | the bandwidth compensation for dBc would resolve the 1 dB difference. | + | |
| - | + | Normally I measure blocking at the onset of AGC, and only at 100 kHz due to common phase noise limitations. I don't agree with the ARRL's method of measuring IP3 and blocking at S5, nominally -93 dBm. Ten-Tec does not use either of these methods to specify blocking. Measuring blocking in a DSP radio is almost meaningless, due to the way the digital AGC is handled by the DSP chip. | |
| - | The only area where measured numbers are significantly different from spec | + | |
| - | is blocking. | + | |
| - | + | ||
| - | Normally I measure blocking at the onset of AGC, and only at 100 kHz due to | + | |
| - | common phase noise limitations. I don't agree with the ARRL's method of | + | |
| - | measuring IP3 and blocking at S5, nominally -93 dBm. Ten-Tec does not use | + | |
| - | either of these methods to specify blocking. Measuring blocking in a DSP | + | |
| - | radio is almost meaningless, due to the way the digital AGC is handled by | + | |
| - | the DSP chip. | + | |
| - | + | ||
| - | + | ||
| The following blocking numbers were done using the ARRL method. | The following blocking numbers were done using the ARRL method. | ||
| - | + | *NF, 500 Hz CW filter: -130 dBm | |
| + | *Blocking at S5 @ 100 kHz 134 dB | ||
| + | *Blocking at S5 @ 20 kHz 119 dB | ||
| + | *Blocking at S5 @ 2 kHz 118 dB | ||
| - | NF, 500 Hz CW filter: -130 dBm | + | Attempting to measure blocking at the specified level of 135 dB @ 20 kHz, I fed in a + 5 dBm signal into the Omni VII. Two things were observed: the S meter went up from S5 to S6, and the audio went down 7 dB. Blocking is not a practical limit on the Omni VII. |
| - | + | ||
| - | Blocking at S5 @ 100 kHz 134 dB | + | |
| - | + | ||
| - | Blocking at S5 @ 20 kHz 119 dB | + | |
| - | + | ||
| - | Blocking at S5 @ 2 kHz 118 dB | + | |
| - | + | ||
| - | + | ||
| - | + | ||
| - | Attempting to measure blocking at the specified level of 135 dB @ 20 kHz, I | + | |
| - | fed in a + 5 dBm signal into the Omni VII. Two things were observed: the S | + | |
| - | meter went up from S5 to S6, and the audio went down 7 dB. Blocking is not | + | |
| - | a practical limit on the Omni VII. | + | |
| - | + | ||
| - | + | ||
| Rob Sherwood | Rob Sherwood | ||
