Topband: Problems with a Home Brew version of the RX 4 Square

[Lee K7TJR]

>>  I built the preamps into plastic boxes taking care
to make them all as identical as possible.

      One of the common errors when building these amps is for each amplifiers transformer to not be phased exactly the same for each amp. It is easy to accidently reverse the phase just by getting the wrong wires on the little transformers. They all need to be the same.

>>I built the phasing/switcher
from the latest Low Band Dxing.

      There is a problem combining these Hi-Z amps by paralleling their outputs in a controller such as the one in Low Band Dxing. Some of the amps in this type controller are seeing only 37.5 ohms at their output instead of the designed 75. This can cause a deterioration of the signal handling capability. This also a;;plies to the phase delay values as a result of their mistermination. Slight but indeed there. The easy way out is to install magic tee combiners where any two cables are paralleled and then scale the phase inverter and possibly the output transformer impedance ratio. The 4-square would probably still work to some degree however without change. 

>>My phasing and feed lines are Alpha 9803C  RG-59 foam coax 
with a VF of 78% and all cut from the same roll.
My long phasing line is 44 feet and the two short lines are 22 feet. My
antenna diagonal spacing is 62 feet 8 inches and my side spacing is 44
feet 4 inches. I used 1/4 wave on 80M feed lines to each antenna which
are 48 feet 8 inches long.

       I calculate your longest feedline as producing only 38Degrees at 1.9Mhz. You need 50 per my calculations for this size 4-square. Same for the short one as it is only 19 degrees and you need 25. 

>>One problem I have is a small yard and the SW vertical is about 5 feet
from a large metal building and the NW vertical is 2 feet away from a 3
foot high metal wire fence.

    The building sure seems a problem to me. I do not think the fence will be much of a problem as you seem to be above it.  I think the Beverage downlead being that close may be a problem also. Too many variables to be definitive here. Both these problems indeterminate until you get it working as I dont think it is now.

>>The 4 square shows - very poor - to no - directivity and when it shows
directivity it seems to be to the wrong heading.

    Are you sure the inverting transformer in the controller is really wired for a phase inversion?
>>Would the short beverages be that much better than the small RX
4 square?

    Not under most circumstances.

 73es Lee K7TJR Oregon