G4AKW

As both the remote station pc and the control pc external IP address are dynamically assigned, the first step is to get the address of the remote station computer. This python script does the job in combination with a cron job and associated cron mail output. --------------------------------------------------------------------------- #!usr/bin/python # # Program gets your external IP address # # This program reads the title from # the whatismyip.com website # # set up SSMTP then put the following line in crontab: # 0 * * * * python /home/geoff/python/ipadd3_new.py # # Cron job will mail output to nominated mail a/c # on the hour with the above. # # The ip address is written to file # ext_ip_add.txt (overwritten) # # Version 1.0 Geoff Robinson Aug 09 fileobject1=open('/home/geoff/python/ext_ip_add.txt','r') oldipaddress = fileobject1.readline() fileobject1.close import urllib url = urllib.URLopener() resp = url.open('http://www.whatismyip.com/automation/nxxxxxxxx.as...

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.

After some tests on Topband a few modifications were made. The 40A bridge rectifier failed and was replaced with 50A one mounted on a better heatsink, the problem appears to be the ability to handle the peak repetitive forward current charging the 30mfarrad capacitors -the specs for the rectifier don't show this value - only average forward current i.e. 50A. A front panel transmit/receive switch was also fitted to replace (temporarily) the control from the FT817. The FT817 transmit control line currently does not provide sufficient delay (pretty sure it can be programmed for sufficient lead-in) to ensure the antenna relay is properly made before the amp delivers full power. The final mod was to the microwave oven step/slow start protection circuit. Instead of a 22 ohm series resistor limiting the primary current, the two 50 ohm resistors were connected in series giving 100 ohms which limits the primary inrush current to 2.4 amps (24 amps in the secondary). The protection rela...