On 1/31/2012 5:06 PM, Stuart Rohre wrote:
Try coiling up part of a mike cable into an orderly solenoid coil,
NOT scramble wound. You can put it on a pop bottle or other pipe
form for a test. If that works, you can measure and compute what
inductance it was and replicate it with a ferrite core, passing the
mike cable thru and around that for fewer turns.
If you want to get deep into the radio, see if there are ferrite
beads on the mike connector wiring, and if not, add that. Beads web
sites usually have application notes on how much equivalent
inductance you get per bead and you can put multiple beads if there
is room. Insulate the beads from contact with chassis or other
conductors.
This may or may not be the time/place to bring this up, but here goes
anyway.
I've got an Omni VI Option 3 and could never run more than ~ 15 watts
without RF getting in to the transmit audio. Tried the above with a
ferrite core and no luck. After years of avoiding SSB, there was finally
talk here on the reflector about the cause of the problem, ultimately
named the "pin 1" problem. (Had something to do with pin 1 on the mic
connector and a floating ground or some such between the connector and
the PC board).
I called TT tech support and they sent me a sheet with the suggested
fix. However, being a CW and digital op, I never worked on the problem.
Several years later, when I had need to get on SSB, I could not find the
sheet TT sent to me. When I called them to get a new sheet, they
disavowed any and all knowledge of the issue.
So, what is happening here? Am I totally hallucinating? Am I missing
something? Does anyone here on the reflector remember the "pin 1"
thread? BTW, TT says too much RF in the shack -- but I've had other
solid state rigs (Drake TR-7) work fine; also, because of the physical
layout of the house/property/trees and zoning and subdivision
restrictions, I am not able to re-locate my antenna as suggested by TT.
Any fixes -- or is this just an inherent issue with the Omni VI?
Any thoughts or comments appreciated...
73,
Carter K8VT
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