To find true north at your QTH:
Go to http://www.usno.navy.mil/USNO/astronomical-applications/data-services/rs-one...
Enter your nearest city and state into the menu
If you prefer to enter latitude and longitude, or if you are outside of the USA, go to http://www.usno.navy.mil/USNO/astronomical-applications/data-services/rs-one...
You will get a chart like this for your location:
Thursday 13 August 2009 Eastern Daylight Time
SUN Begin civil twilight 5:50 a.m. Sunrise 6:19 a.m. Sun transit 1:12 p.m. Sunset 8:05 p.m. End civil twilight 8:33 p.m.
MOON Moonrise 11:04 p.m. on preceding day Moon transit 6:29 a.m. Moonset 2:04 p.m. Moonrise 11:44 p.m. Moonset 3:13 p.m. on following day
Make a note of the "Sun transit" time. Set your watch by WWV or some other reliable time source. Drive a stake in the ground (use a plumb line to make sure it is vertical). Go outside at the exact moment of the sun transit, at that time the shadow of the stake (or your tower if it is vertical) will be true north. Mark the ground at that exact time.
Dan Schultz N8FGV