20 M DELTA LOOP AT NN6AA QTH AND FLEX 1500 RADIO PLUS TOKYO HY PWR AMP...
Something I like to do is Play Ham Radio, there is so much you can do and you will never get to know everything but YOU can try....
Saturday, 9 October 2010
Comet CHA250 Broadband Vertical
Following my discovery that eHam have pulled my review of the CHA250 (done a couple of years ago and was on the site for a long while) I thought I would make a graphic demonstration of how this antenna compares with an alternative 'restricted space' antenna, the Cobwebb. This video seeks only to present the truth, as seen by the front end of a receiver; the one with the most accurate S-meter available in the amateur radio world...
The Cobwebb is mounted 2 metres higher than the mean height of the CHA250, which in terms of HF is not significant. The CHA250's feeder has 0.3dB less loss than the Cobwebb @ 21 MHz.
The test receiver is a Flex-5000 SDR which has a calibrated S-meter, not AGC derived and is highly accurate, making it the ideal choice for this test. Combined with the identical second receiver, true A/B comparisons are easily accomplished in real time.
A/B tests don't exist for the CHA250 in its previous mounting location however I firmly believe that it performed considerably better at 2.5m AGL than it does at 7m (feedpoint).
The Cobwebb is mounted 2 metres higher than the mean height of the CHA250, which in terms of HF is not significant. The CHA250's feeder has 0.3dB less loss than the Cobwebb @ 21 MHz.
The test receiver is a Flex-5000 SDR which has a calibrated S-meter, not AGC derived and is highly accurate, making it the ideal choice for this test. Combined with the identical second receiver, true A/B comparisons are easily accomplished in real time.
A/B tests don't exist for the CHA250 in its previous mounting location however I firmly believe that it performed considerably better at 2.5m AGL than it does at 7m (feedpoint).