Topband Vertical Antenna

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.

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FT 817 Power Amplifier

This very simple 2 Fet power amplifier easily achieves 250W output with an FT817 5W drive. The key design details as follows: 3:1 broadband input transformer matches the 5.5 ohm gate load resistor (4 x 22 ohms in parallel) to the 50 ohms required by the FT817 . The 4:1 output broadband transformer presents 3 ohms (16:1 impedance ratio) to the balanced HEXFET pair each mounted on a 3mm copper heat spreader which is insulated from the 2 1w/degC heatsinks. These are blown cool by a fan underneath. The power supply required is 28v at 30 amps. The amp is around 50% efficient with a standing 750mAmp temperature compensated bias. An IC 703, with 10watts output will drive the output to around 400 watts. The output filter shown is a 5 pole topband filter with T130-2 torroids and 400v silver mica caps. Peak output voltage on 160 metres with 5 watts drive is 160v or 320v p-p in 50 ohms equating to 250watts. This is slightly higher than the reading on the 3kw MFJ power meter. The inline F...

Splunk Cheat Sheet (Linux)

1. set root's password: sudo su passwd root Enter new UNIX password: < new_root_password > Retype new UNIX password: < new_root_password > passwd: password updated successfully # su - 2. Remove any existing Splunk directories & create user etc: # rm -rf /opt/splunkforwarder # userdel -r splunk # this will remove as above if user splunk's home directory # groupadd siem # useradd -g siem -s /bin/bash -d /home/siem -m siem # vi ~/.profile # chage -I -1 -m -0 -M -99999 -E -1 siem If above fails because of multiple passwd fails: # pam_tally --reset check with #chage -l siem # uname -a # check OS version # dpkg -i splunk-4.3.1...........intel.deb # chown -R siem:siem /opt/splunk # su - siem : $SPLUNK_HOME/bin/splunk start --accept-license : $SPLUNK_HOME/bin/splunk edit user admin -password newpassword -role admin -auth admin:changeme 3. vi ~/.profile (as follows) (OR .bash_profile) # ~/.profile: executed by the command interpreter for log...

Beautiful Soup HTML parsing The following Python code fetches the specific windspeed web page and extracts the timestamp, average windspeed, direction, gust speed and writes out data to a date stamped file named say /home/user/wind_data/windspeed_date(2015-04-21-12).txt. Schedule a cron job to run this every day at midnight say. The windspeed file can be selected for a particular day and processed by graph.py. #!/usr/bin/python import os import requests import time from bs4 import BeautifulSoup date_stamp = time.strftime('%Y-%m-%d-%H',(time.localtime(time.time()))) outfile = os.path.join(os.path.expanduser('~'), 'wind_data', "windspeed_%s.txt"%date_stamp) f = open(outfile,'w') list = [] r = requests.get("http://xxxxx.wwww.yyyyy") soup = BeautifulSoup(r.content) table = soup.find("table", {"id":"grid"}) for line in table.findAll('tr'): for l in line.findAll('td'): ...

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