Sunday, 27 August 2017

4 * 25 el DG7YBN again

Finnally I have found the time to mount all elements for the 4 new 25 el dg7ybn antennas.
It takes some time to press and adjust 96 elements into the booms.
Try to adjust to 0.1 mm tolerance equal on each side of the boom and it works good but time consuming.
Put a dipole on the first one and tested and the measurements corrolates well to simulations and to the 4 yagis I built last year.
The weather was not good today with a lot of rain the whole day making tuning difficult but managed to get a few measurements in between showers.

Ordered a DEMI 70 cm transverter  kit with an additional oscillator board for higher stability when connected to 10MHz reference.
Hope it will arrive in the next few weeks and that customs consider the value to low to bother import tax and duty. It happens occationally that they don't care of some shippments from US.

Will continue this week with the dipoles for the antennas and to finalize the rotator system.
Final tuning of the antennas will be done when mounted in the system.
Planning to use 1,4 meter RFC400 Cables from antenna feedpoint to a power divider of the typ 4 way λ/2 splitter thats 1730mm long.
This corresponds to 5 λ/4 on each side making it possible to use short cables.
The two Groups of 4 yagis will be combined with 4 meters of 1/2" LDF into a 2 to 1 divider.
Will be some 0.35 dB loss in feeding cables but feels that the time to build and adjust a open wire feed is not there so its a subject of improvement for the future.

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