VERY nice looking filter, Jim, and as good or better than any commercial
product I've seen advertised. Is your build designed to handle TX power,
or RX only?
One caveat -- filter performance depends on both source and load
impedance, which are controlled in the VNA, but are not in some ham RX
front ends, and may not be in the source. I've measured input Z of my K3
RX, and learned that they are 50 ohms with a bandpass filter in front of
them for each band.
73, Jim K9YC
On 10/26/2021 2:49 PM, AA5CT via RFI wrote:
Or, build this model and save a few bucks! This high pass model
yields 40 dB attenuation starting at 1700 kHz and gets better further
down in the band.
Article comparing performance with existing filters (at the time):
https://www.qsl.net/wb5wpa/Filter/AM Brick-Wall 160 Meter Filter.pdf
Schematic and performance:
https://www.qsl.net/wb5wpa/Filter/DesignAMBrickWall_08.pdf
BTW, the RigExpert AA-55 Zoom will perform within 1 kHz of a strong
AM carrier (like, measured 0 dBm or 1 mW on the antenna) from say a
station at 1700 kHz and tuning the antenna for same. If the AA-55 is tuned
to 1700 kHz exactly one sees a 'beat note' (bouncing RL value) on the meter.
They do not use a broadband detector in that analyzer.
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