Did you put
100n, 10n, 1n
filter capacitors
?all in parallel on both input and output
directly across the 78L05 leads?
.
On Sun, Jul 1, 2018 at 2:31 PM, Rick Price
<rickprice48@...> wrote:
John, Don, others,
Yesterday I attached a 78L05 (TO220) directly to the back of
the AGC board that is mounted to the RF gain control on the front panel.
Bypassed all power leads and ran a separate power lead to the 12V regulator that
powers?my uBitx. In other words the AGC board had its own isolated(?) power
source. Stll heard the audio when transmitting.? Beginning to think that
radiated power is being absorbed by the AGC board and then recitifed and then
coupled into the audio system. I also have the pop click board installed and not
sure if this was a problem before it was installed. My AGC board is one I
fabricated using Don's technique of cutting pcb with an x-acto knife.? I
also have a AGC board made on perf board using through hole parts.? May sub
that in and see if there are any changes. I eventually plan on installing the
JackAl mod when it becomes available so this problem should go away for
me?but its beginning to become a challenge to fix.
?
Rick KN4AIE
Don,
I spent part of yesterday applying ferrites to this and that
to little success. I also tried wrapping the 5v line around the twisted pair
coming from the volume pot and that did some good. This morning I was thinking
about fixing a 7805 to the metal base of my case, drilling a hole in the ground
plane and routing a wire through that hole to feed the AGC board. It could be
driven off the 12v relay (K1?). Has anyone else had any
ideas/success?
John
KC9OJV
