An alternative to the 6M7JHV antenna for 6m / 50MHz
Making the front section of the boom
The first task is to cut the booms to lengths of 4786mm
Preferably, this should be done with a cross cut saw but, if one is not available, use a 12" hacksaw with a 90 degree mitre gauge.
Cutting the two booms to length
Now drill the 2500mm with 4 holes spaced from one end - 150mm - 1100mm - 1400mm - and 2350mm marking up the boom using the same technique as used on the back boom. Also mark the centre position of the boom at 1250mm.
Drilling the support boom
Clamp the support boom to the back boom aligning the end of the back boom to the middle of the support boom.
Mark the position of the two holes on the back boom
Use two M6 x 90mm stainless steel screws to attach the boom support to the back boom.
Screw the back boom and the boom support together
This is how it looks when finished.
We now need to attach the front 5000mm section of the boom.
Clamp the front boom to the support boom and, as before, use a hand drill to mark the position of the holes and then use the bench drill to drill them. They can then be attached to create the near 10000mm boom.
The boom bolted together using the support boom
( I've built two!)
An important tip!: The tape rule is extended 10 metres when measuring the positions of the last three elements. If it slips off the boom you will get an error! All you need to do to prevent this is to use several pieces of garden wire wrapped round the boom and the tape to hold it to the boom for the whole length of the antenna.
The holes for the last three elements can now be marked out in the same way as the front section of the boom and then drilled.
Note: D3 is positioned above the support boom so the element clamp holes need to be drill through the front section of the boom and the support boom (110mm screws will be required to hold D3 to the boom).
The hole position of the last element - 30mm from the end!
Once all the holes element holes have been drilled, the last job is drill the holes for the strain relief eye bolts. The front one is mounted 1000mm from the front of the beam.
Tip: Always use some Vaseline on the screws before doing them up as this prevents the stainless steel screws possibly locking up!
The front section strain 6mm relief eye bolt
The strain relief eye bolt is mounted 1000mm from the back of the boom. Note: I originally placed it 170mm but this was too far back).
That's it - the complete boom is finished!