Friday, August 12, 2011

The Clifton Labs Z1501 Active Antenna - Pt 2 Initial Tests

I didn't have enough coax at hand, so for the first test run, the Z1501 was put up with the 1.5 m whip alongside the house wall. Not a favourable position with regards to RFI, but enough to see how (and if) it worked, and to make a brief A-B test with the Mini-Whip.

It has gain all right. I feared that the semi-local Loran C transmitter (250 kW on 100 kHz 14 km away) would make trouble when I connected the Z1501 to my Winradio Excalibur SDR. The Excalibur has no band pass filters or preselectors, so in principle it is wide open.

I was right. I got ADC clipping and needed to attenuate 12 dB to get rid of it. I assume though, that conventional receivers with band pass filters or tracking preselectors will not be affected. Anyway I am used to Loran C trouble, so I have a suite of 100 kHz notch filters, one of which was inserted between the DC Coupler and the Excalibur. Loran C gone.

To compare with the Mini-Whip, I mounted the latter at the same height as the Z1501 enclosure and ran a few tests.
Mini-Whip MW Response 
Z1501 MW Response
The difference in this daytime test (almost no stations audible) is significant. The 1449 Radio Rossii signal is 15 dB higher on the Z1501. But keep in mind that the price tag is at least "15 dB" higher too. It's a bit like comparing a Ferrari to a Fiat 500.

And I still haven't put the 3 meter whip on...

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