Topband: Amplifier Help

[Richard (Rick) Karlquist]

GEORGE WALLNER wrote:
> 
> 
> 
>   Niko Cimbur <ac6dd at yahoo.com> wrote:
>> Can something like this be easily done?  
>> I am not familiar with the two 750W amps they have, but 
>> Would it be possible to build a 4 square and feed each 
>> element with its own amplifier and switched phase delay?  
> 
> Niko,
> 
> I have done this with a two element array and it worked 
> great. Phasing control is much easier at low power levels, 
> i.e. ahead of the amplifiers. You have to ensure that each 
> antenna is matched properly. (I used LC matching 
> circuits.) Driving a 4SQ is more complex but should be 
> possible.
> 
> George, AA7JV

How did you determine it worked great?  In most two element
arrays the impedance of the rear element is virtually a
short circuit.  The second amplifier goes to waste as it
cannot deliver any significant power into this load.  You
basically lose 3 dB compared to using a hybrid combiner to
make the two 750W amps into one 1500W amp and then using a
conventional feed, like a W7EL feed.

Rick N6RK