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JBX21-C/D Tests

Results Definition:

  • XX-XX = Measured signal strength level

  • 0-XX-XX = Signal locks on briefly but keeps dropping out

  • 0-50 = Signal was detected but not able to lock

  • 0 = No signal detected

Note: Signal level refers to the Dish 6000 indicator which measures the signal quality based on percentage of errors. As long as the indicator stays above 48-50%, the signal will lock. I assume that if you have over 50% errors, the Dish 6000 does not have enough good signal to decode properly. A reading of 100% would indicate no errors in signal. I have found that at 47% I will see pixelation in the picture and below 46% the picture will drop out completely.

 

**For easier printing, click on image to bring up a separate page containing just results.

Test #1, Date: 1/19/02

Conclusion:

  • The coax balun improved the bandwidth of antenna. I tried a shorter 5.25" coax to see if it improved upper channels, but overall the results were not as good as the 6.50" balun. Next test will include a 7.75" coax balun. I did not include the Blake balun in this test, but with it ch 31-36 would not come in at all and the signal levels were lower on other channels. I will include the Blake balun in the next test.
  • The Low Noise Amp (LNA) increased signal quality in almost every case. The amp may be overpowering some channels as can be seen in the higher signal readings using the 6 db attenuator.
  • This is also the first time I have ever gotten a locked signal on ch 53. I could only lock the channel long enough to save it in the setup menu. When I tune in to the channel through the guide, I get a signal of 42-45 that lasts about 3-5 seconds, but I never see a picture. This at least gives me a new target to shoot at.

 

Test #2, Date: 1/20/02

Conclusion:

  • The Blake PCB balun was included in this test. Overall it did not work as well as the coax baluns.
  • I tried three different coax baluns, 5.25", 6.50", and 7.75". These 4:1 baluns will convert the 300 ohm feed from the pickup element into 75 ohm.
  • The 7.75" coax balun seemed to be the best match for this antenna, as can be seen by the increased signal quality in the upper channels and a decrease in the lower channels. Since this antenna is intended to improve upper channels, I did not mind sacrificing the lower channels a little. I will try a longer balun next (maybe 9.00") to see if the upper channels can be improved even more.
  • The LNA seemed to work best overall with a 6db attenuator placed inline at the receiver.

 

 

  


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