ZL1RS - Antennas

2m Yagi - YU7EF EF0213M


2m Yagi - YU7EF EF0213M

September 2020. An SWR fault occurred in the 9-over-9 stacked Yagi array for 2m that had been in use here for the last 9 months (according to the symptoms, probably an intermittent connector in the phasing harness or power divider). It could have been repaired with out much effort, but I took the opportunity to replace the array with a YU7EF EF0213M 2m Yagi built on an 8m long boom that happened to be in the 'antenna graveyard' behind my shed.

Split dipole driven element with DG7YBN Coax_Quarter_Wave_Line_Concept Balun. The connections have since been waterproofed:

The feedline connector grounded to the boom:

'Boom correction' factors were added according to the type of element mounting insulators used and the various metallic boom thicknesses along the length of the Yagi, but the SWR curve was not quite the same as the YU7EF result. However, it is 'near enough':

Update: 21 October 2020. While the Yagi certainly performed well, in certain wind directions a mechanical resonance occurred between the 8m long Yagi boom and the aluminium scaffold tube rotating mast which caused an undesirable shaking of both the antenna and mast. This effect was quite alarming in very strong winds, so I reverted to the old 9-over-9 stacked Yagi array with some small changes.

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