The following experiments were conducted on Saturday 17 May 2003,  from our normal meeting site at Treviglas School,  Newquay.   We took the oppurtunity of a two metre contest taking place to be able to hear a few stations and contact them in order to get an idea how well the different antennas worked.

    We started off by erecting the club's eight over eight at a height of twenty feet.   This was fed by a new co-ax balun arrangement.   Various experiments were conducted.   The balun was then replaced by the original maker's balun and the experiments were repeated.   Finally the antenna was replaced with a nine element Tonna and all the measurements repeated.

    The results are shown below in tabular form.
 
 

Notes

1.    The SWR was measured with a Bird Thruline wattmeter.   The forward power was adjusted to be fullscale deflection of 25 watts.   At this power level the reverse power was not easily measured,  but the comaprative figures give a good indication of the change between the various aerial arrangements.

2.    The strength of the Poldhu Beacon was such that with the beam turned off the beacon it was hardly audible.   With the beam directed at the beacon the "S-meter" showed the strengths shown.   It was very noticeable the QSB on the signal.   The maximum strengths shown were only reached on fleeting peaks,  and therefore not a very good indication of the gain of the beam.   However a subjective comparison showed very little difference (if any) between the various antenna arrangements.
 

Conclusions
    It was concluded that the best antenna to use was the nine element Tonna.   This decision was based on the following facts:

            1.    The gain seemed similar to the 8 over 8
            2.    The SWR was better than the 8 over 8
            3.    The size and weight of the Tonna was a lot less than the 8 over 8,  and thus was much easier to erct and handle.