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Updating the 6M7JHV for FT8

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With the rapid expansion of FT8 and other digital mode activity on 6M moving higher in the band, some customers are experiencing higher than optimum VSWR in the 50.300 MHz range.  We are offering some adjustments to the 6M7JHV to accommodate this frequency shift for existing customers.  To move the resonance higher in frequency, cut each element half using the dimensions below.  The reflector remains unchanged since it increases the F/B ratio over the original design.  No changes to the spacing are required.

This document applies to the 6M7JHV only, not the 6M7JHV-HD or 6M7.


Two different shorting bar settings have been documented.  One has a deeper null around 50.330 MHz but sacrifices the VSWR below 50.100 MHz.  The second setting is a bit more flat with a 1.4:1 VSWR at 50.100 MHz  You can adjust the shorting bar position outside of the published settings to tweak the VSWR curve to fit your operating preference and to compensate for site specific interactions

Shorting bar position.  Measured outside of DE block to inside of shorting bar.

11.375"  - Optimized for FT8, 1.5:1 @ 50.100 MHz.

10.4375" - Broadband.  1.6:1 @ 50.000 MHz, 1.7:1 @ 50.500 MHz.

ORIGINALNEW
R57.625"NO CHANGE
DE57.25"56.25"
D154.125"53.875"
D253.188"52.875"
D3
52.562"52.313"
D451.25"51.0"
D550.688"50.5"

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