Hi Steve,
The amount by which you needed to increase the gain in the Orion is
approximately the attenuation of the pad. I strongly recommend against
using such a pad external to the radio on a microphone. A pad IS usually
needed when we feed a Line Level signal to a mic input. I don't know
anything about the Orion, so can't help with adjustment of controls or
the pin-out of connectors. You've got to look that up in the manuals.
I know that K8JHR wrote a QST article recommending it. Nothing personal,
but I'm an EE and audio engineer by profession. He's not. :) Last I
heard, material for QST is not reviewed for accuracy, and I cringe every
month at least once.
As to RFI -- carefully look at where the shields on the mic cable are
connected at the rig. The ONLY proper connection of a cable shield is
the CHASSIS. Many (most?) rigs screw up and connect it to the PC board
instead. They call it "mic ground." Such a failure to connect the shield
to the chassis is a MAJOR cause of RFI. In my rigs, if the connector
shell is bonded to the chassis, that's where I connect the mic shield.
If you are able to connect these shields to the chassis (DIRECTLY), it
will likely solve your RFI issues. Both mic and headphone cables can
couple RFI via this design error.
Neil Muncy, ex-W3WJE (SK) is generally credited with discovering and
publishing about this in the Journal of the Audio Engineering Society in
1995. Because Pin 1 of the XLR connectors is the designated shield
contact, he named it "The Pin One Problem."
All the radios I looked at in Dayton booths last year appeared to have
Pin One Problems at most of their accessory connectors. The tell-tale
clue is a connector mounted to a PC board poking through a hole in the
chassis.
There's a lot of tutorial material on my website about The Pin One
Problem. k9yc.com/publish.htm
73, Jim K9YC
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