Well, as mentioned in the previous post I forgot about todays lunchtime net – even after telling everyone it'd definitely be on. Again, I apologise for that. But here is the post detailing what I was doing…
Today I designed and fabricated a bracket to hold an N socket for connecting to my 70cm cheap yagi (see photos and video below). The idea being, that the main body of the bracket will be attached to the boom and flush up against the part of the driven element which the shield of the coax is connected too. Then, the center pin of the socket is mounted such that it lines up with the 'J section' of the driven element. From the center pin a piece of copper wire will be soldered and then will connect to the J section through a hole drilled in the element and then wrapped around it (and possibly also soldered for extra strength). Finally (or, probably first up) the bracket will simply be hot glued to the boom to minimise any additional metal.
Hopefully this all works out, but I have three concerns:
1. All the extra metal for the bracket – hope it doesn't disrupt things too much;
2. The quality of the connections – I don't have the equipment (nor skills – yet) to be able to solder to aluminium; and
3. The strength of the bracket with only hot glue – time will tell if I need to screw it to the boom for strength.
But, at least I finally have a design for the bracket, so from here I can do as many iterations as I'm willing to perfect it – first of which is for the planned 2 4el 2m beams for stacking. But here's to the prototype!!
(Oh, on a side note. I've also modified the reflector and DE length of the beam after modelling with 4nec2 so that the beam will be targeted at 439MHz instead – so that I can use it for FM as planned. The changes got the SWR down to about 1.2:1 for about 438 through to I think about 450 – and still with a gain of around 11dBi and a good F/B ratio. Once I've tested the SWR, I'll share the details and NEC model for any interested.)