I tested the DXE whip. I could get just as good sensitivity
using a CB whip and a passive transformer match, and with a
conventional 50 ohm preamp in the line. The DXE had serious
BC band overload problems from a 50 kW station 6 miles away.
The front end tank circuit on the DXE was able to allow operation
on 80 and 40 but was not selective enough for 160. As long
as you can match the impedance with a transformer, you don't
need an active whip. I demonstrated that a 102 inch CB whip
on 160 is just within reach of a transformer. For shorter
whips and/or lower frequencies (like 136 kHz), active whips
start to make sense.
Another issue not directly related to active vs passive is
that at my QTH, verticals are always noisier receive antennas
> -----Original Message-----
> From: firstname.lastname@example.org
> [mailto:email@example.com]On Behalf Of Jim Lux
> Sent: Friday, March 16, 2007 1:32 PM
> To: TowerTalk@contesting.com
> Subject: [TowerTalk] active antennas, real data?
> Not really a tower, but HF antenna nonetheless...
> I'm looking for some real test data on active HF antennas (e.g. the
> ones from DX Engineering, or the antenna from AMRAD), in particular,
> any noise figure or gain measurements, as well as subjective
> experience with things like intermods in a multisignal environment.
> Jim, W6RMK
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