An alternative to the 6M7JHV antenna for 6m / 50MHz
The troublesome phasing harness
The phasing harness originally made by M2 consists of two quarter wavelength sections of RG11 75 Ohm cable. I discovered that these were cut to 52MHz but it does not affect performance and have used them since 1998! However, I'll probably make a new pair cut to 50.11MHz.
The M2 phasing harness
The phasing harness
I was a bit taken aback when I first connected up the stack as things did not seem right as the antennas were 'resonating on the low side which was quite different to the individual antennas when tested separately. This threw me for a bit as I was still using the M2 harness that I had been using for over a decade and this was the only thing that could be at fault I thought.
Looking at the M2 harness specification, it said it was cut for 52MHz which, I guess, is the centre of the US 6m band. I did not think that that could affect things but I made a new harness using two 1020mm lengths (end of plug to end of plug) of RG11AU 75 Ohm cable (velocity factor of 0.75) and tried these.
I have no idea why the M2 harness caused me problems, but using the analyser it was definitely cut to 52Mhz but turned out to be 100mm longer than the new ones I made!! Who knows! Anyway, everything came right in the end.