Richard Harrison wrote:

Yuri, K3BU wrote:
"Learned it to be a no-no trying to feed phased arrays with individual
amplifiers, at the same frequency."

I`m not sure separate amplifiers have anything to do with distortion
because I`ve seen distortion at certain azimuths from arrays driven by
a single amplifier.

Drive around a broadcast array with sharp nulls while listening. You
will notice severe distortion at the edges of sharp nulls. I always
attributed this to phase out of the carrier frequency at an azumuth
where the sidebands aren`t completely nulled out, and this produces the
overmodulation and distortion. It`s only a speculation to explain the
cause of an observed effect.

Best regards, Richard Harrison, KB5WZI


I wonder if we can really define that as distortion. It's distortion to
you at the time perhaps, since the whole signal as you'd like it to be
delivered is not there while you drive through the null. However, the
antenna system is just doing its job, and doing it well in the
directions it was intended. The nulls are by nature not supposed to
contain signals with smooth frequency response, since they aren't
supposed to contain any signal at all if perfect, correct?

tom
K0TAR

"Richard Harrison" wrote in message
...
Yuri, K3BU wrote:
"Learned it to be a no-no trying to feed phased arrays with individual
amplifiers, at the same frequency."

I`m not sure separate amplifiers have anything to do with distortion
because I`ve seen distortion at certain azimuths from arrays driven by
a single amplifier.

Drive around a broadcast array with sharp nulls while listening. You
will notice severe distortion at the edges of sharp nulls. I always
attributed this to phase out of the carrier frequency at an azumuth
where the sidebands aren`t completely nulled out, and this produces the
overmodulation and distortion. It`s only a speculation to explain the
cause of an observed effect.

Best regards, Richard Harrison, KB5WZI


The effect, distortion, seemed to be noticeable in any or all directions and
over DX path. The only thing we could figure out, was that it had to do with
separate amps feeding separate ants. Switching to either one, signals were
clean. Feeding two antennas from one exciter through hybrid was no problem.
In my case it was 4 square and Inv Vee about 3/8 wave away.
I have heard the same effect on one YU station, and he was getting reports
of raspy signal and when I told him to turn the other amp off, he was clean.
The distortion was quite significant, it produced complaints from about one
in five stations worked. Closest thing to describe it, would like signals
distorted by Aurora.

73 Yuri, K3BU