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.