[ Reply | Next | Previous | Up ]
From: Maurice Hately, GM3HAT
Date: 5/12/99
Time: 1:34:46 PM
Remote Name: 62.172.86.139
Suggest E-plate cylinder about 4 ins diam, and 5 ins tall. D-plate disc then 6 ins diam with centre hole 1.5 ins diam. Ground Plane 1ft 3ins square. Gaps between E-plate to D-plate and D-plate to GP each 1 inch. Phasing circuit as in the 8o metre construction article except the transformer reduced to 9 turns, and the other coils reduced to 6 turns, and capacitors reduced to 75 pf variables. Leads should be very short therefore the Phasing Unit components should be under-neath the GP and the variable caps moved by long insulated rods or long insulated screwdrivers with slot in the variable's shafts. Always work with two hands together. It is like balancing an RF bridge.......successive aproximation to optimise towards the goal of 1:1 SWR (usually the same setting as giving maximum radiation, but not always! There are some unwanted resonant conditions with very narrow bandwidth, and low SWR which do not produce radiation. Avoid these and re-try. Good Phasing ! 73 Maurice.