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588sherwood [2007/04/10 16:39]
n5na
588sherwood [2007/04/10 17:18]
n5na
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 |DR3 2 kHz (dB)  |  78  |  80  | |DR3 2 kHz (dB)  |  78  |  80  |
 |Sensitivity,​ preamp off: (uV) |  0.5  |  0.45   | |Sensitivity,​ preamp off: (uV) |  0.5  |  0.45   |
-|Sensitivity,​ preamp on: (uV)  |  0.18  |  0.17 uV  |+|Sensitivity,​ preamp on: (uV)  |  0.18  |  0.17  |
 |Noise floor, preamp off: (dBm) |  |  -130  | |Noise floor, preamp off: (dBm) |  |  -130  |
 |Noise floor, preamp on: (dBm) |    |  -140  | |Noise floor, preamp on: (dBm) |    |  -140  |
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-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
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 Sherwood Engineering,​ Inc. Sherwood Engineering,​ Inc.
  
-NC0B   ​+NC0B 
 + 
 +---- 
 +[[http://​www.sherweng.com/​table.html|Rob Sherwood'​s Complete Receiver Test Data Table]]

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