Wednesday, August 26, 2015

Tuning the 8-L 6-M InnovAntennas LFA-2 Yagi

Antenna at 39-feet on K8RRT's Tower
Over a period of a few days, I have been "tuning" the new 6-M antenna.  It has taken that time because the antenna is being tuned at Tim, K8RRT's QTH and to be frank, I have not been feeling all that good.  But, I think yesterday (8/25/2015) we have the antenna working about as well as it can.

SWR @ 39-feet on K8RRT's Tower
On the left you can see the antenna in it's test location.  I put the gin pole up on Tim's Rohn 45G tower and used it to pull the antenna up to about 39-feet for testing.  You can see the truss support I added by clamping a 5-foot piece of aluminum angle to the square boom.  This makes it much easier to level the antenna at ground level instead of on top of the tower.  If you noticed the reflector is bent - that is by design!  You can click on any image to see it larger.

Once the readings were taken at that height, the antenna was lowered to ground level using the gin pole rope and adjustments were made.  The antenna was then pulled back up and more measurements were made.  The feedline connecting to the antenna was a 50-foot length of 1/4-inch Heliax.  The analyzer (courtesy of Rick, W8ZT) was a Rig Expert AA-54 Antenna Analyzer.  The readings were saved to the analyzer and uploaded to my computer for analysis.

Bringing it Home
On the right you can see the SWR plot.  The graph's are centered on 50.200 MHz and goes plus or minus 1 MHz from that point.  The SWR at 50.200 MHz is 1.13:1 which looks pretty good to me!  The best SWR seen was 1.06:1 across the range of 50.460 - 50.500 MHz.  On the left is a graph showing the complex impedances across the same range

Finally, on the right, is an image of how the antenna was transported back to my QTH.  My co-pilot was invaluable in keeping me advised of potential hazards on the right side of the vehicle.  We brought the driven element half of the antenna home at 7:30 p.m. so traffic was very light.  Now I need to retrieve the second half of the antenna.

UPDATE - Second half of the antenna was returned with no problems (8/26/2015.)

No comments: