Chris Trask wrote on Feb 4.
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"In
my design (in the group files section) I chose a 12V supply rail as it was best
suited for direct operation from 12V batteries, such as Gel Cells, which would
take care of any concerns of power supply induced noise. The biasing of the two
stages was selected to give a decent power consumption vs. performance. At HF
frequencies the NF performance is secondary to IMD performance due to
terrestrial and galactic background noise and the presence of numerous
high-power broadcast stations.
The
performance of my amplifier exceeds that of Pixel and Wellbrook, having a 2.42dB
NF at 10MHz. To get better IMD performance than I attained would require a 2W or
more power amplifier, which would at least double the power consumption. Using
an older transistor such as the 2N3553 or a newer device such as the NE46134 in
the output stage and boosting the biasing current to 100mA or so would do
it.
Chris"
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Hello Chris,
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Running? Pixel loops from a Wellbrook ALA1530 Antenna
Interface with a 12V dc supply makes little difference unless you are measuring
the IOP3 which only changes by a few dBm.
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Concerning your last paragragh which you have repeated many
times. I am not aware that any one else in the group has been able to get your
design working. The NF of Pixel and Wellbrook loops is in the region of 2dB; so
I don't see an issue here. Wellbrooks ALA1530S+ Imperium has a much more
impressive IOP3 of +55dBm.
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73
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Andrew
