It's not a great vertical by any standards, but on the plus side, its cheap, fits in a small garden, could be considered a temporary structure, is dual band by just removing the bottom loading coil and capacitor and.... just add more pwr for more erp. The total height is 43 ft - 10m fishing pole up 3 m off the ground, attached to a 27ft ex - army telescopic mast. Centre loading coil is just above the main mast at about 30 ft - 110 turns of 2.5mm square wire on a piece of waste pipe. This matches the antenna without further components at the CW end of 80m. The addition of a further series loading coil and 1000 pf cap at the base matches it on 160m. Currently with just 4 radials the match is 1:1.4 between 1820kHz and 1840kHz - best DX to date is eastern US with CW and 400W.
The following GNU radio application adds a waterfall spectrogram to the previous CW filter program. The plot show 4 CW signals in the audio band (lower sideband) at 7023 kHz. The 700Hz signal is filtered and output to the laptop headphones by the CW bandpass filter. The frequency display is shown after the script which is as follows: #!/usr/bin/env python from gnuradio import gr from gnuradio import audio from lpf_bpf_class import Bandpass from gnuradio.qtgui import qtgui from PyQt4 import QtGui import sys, sip class cw_filter(gr.top_block): def __init__(self): gr.top_block.__init__(self) sample_rate = 44100 out_rate = 8000 kaiser = Bandpass() cw_flr = gr.fir_filter_fff(1, kaiser.bpftaps) decimate = int(sample_rate/out_rate) Bandpass.cutoff1 = 3000 pre_decim = Bandpass() dec_flr = gr.fir_filter_fff(1, pre_decim.lpftaps) dec = gr.keep_one_in_n(gr.sizeof_float, decima
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