Bob Sutton - ZL1RS

6m Station

 

The header photo shows the stacked G0KSC LFA Yagis previously used here for 6m. They were destroyed in a storm on 15 April 2013. Since 23 April 2013 until June 2014 I was using a 7 element Yagi on a 9.6m boom (own design). Now under evaluation since June 2014 is a prototype 6 element Yagi for a stacked array (future plan). It does not have maximum gain for the boomlength, but it does have a very clean pattern especially when stacked in an array. After these experiments I understand how beneficial a clean radiation pattern is for very weak signal 'work' ... even in this quiet countryside QTH.

The current 6m equipment line-up at ZL1RS is:
Icom IC-7600 with audio via USB to a laptop running ham radio software (WSJT, Spectrum Lab, etc)
Bencher Paddles for CW
Home made GaAsFET preamp plugged into the RX ANT In-Out sockets on the rear of the 7600
HB 8877 amplifier





The present 6m antenna as from June 2014 is:



A home made, own design 6 element Yagi. This antenna was especially designed to have exceptionally low side lobes (clean pattern) in an array. The clean radiation pattern seems to help RX performance judging by the signals received via EME. The clean pattern reduces local noise sources. We have some local noise even though we live in a country setting 15km from the nearest town ... I can hear the power lines that are 3km away running along the roads to the SE and NE. The Yagi's feedpoint impedance is 28 ohms and is matched by a 1/4 WL coax transformer and balun (a modified "DK7ZB match"). Special effort was made to get the physical antenna to replicate the computer design with a boom compensation factor determined for the particular mounting insulators used, and with dimensions made to within 1mm. The SWR 'curve' follows the computer model almost exactly and is essentially flat at 1:1 SWR from 50 to 50.3 MHz. The main feed line to the shack is 20 meters of LMR-400.

Here is the computer simulation of the present 6 element Yagi on a 5.7m boom:



The reality is almost the same in both the SWR curve and observed radiation pattern.


Here is the previous 7 element Yagi on a 9.6m boom used from April 2013 until June 2014:





Highly suppressed rear lobes. The reality was not quite as good, but still very effective at reducing local noise off the back half of the antenna.


The earlier antenna system was:
A home made stack of two 6 element G0KSC LFA Yagis for 6m (the "stacking version"). I chose this antenna as it has very low side and back lobes when stacked to reduce pickup of any local noise sources. The two Yagis were phased together with 75 ohm CATV hardline with 3 ferrite cores at each feedpoint as a choke balun. The phasing lines were also tightly taped to the booms and support mast to further decouple the coax outer. There was only one connector in the whole transmission line system ... at the station end. All other joints were done by mechanical and solder means.


The wreckage after a wind storm on 15 April 2013

The small aluminium tower and scaffold tube rotating mast will eventually be replaced by the bigger galvanised tower that can be seen laying in the grass (this tower was holding the 2 element 80m Quad I had up at my old QTH). When installed, the tower will hold something a little bit bigger on 6m than the previous experimental antennas.

 

 

 

 

Thanks to QSL.NET for the free website hosting!

counter
Page views since 22 Nov 1997
Last update 24 Oct 2014
... and still written on notepad!

Return to the Front Page