With all respect, Jim, I'd like to keep this discussion to the technical
problem at hand rather than attempt to fix the manufacturers' perceived
shortcomings. There are lots of rig uniquenesses, and they usually bite
each of us at one time or another, but since I originated this thread,
let's not get off into this wide ranging discussion again that we just
had last month.
Thanks and 73,
Duane AC5AA
On Fri, 23 Jul 2004 10:35:45 -0500 "Jim Brown"
<jim@audiosystemsgroup.com> writes:
> On Fri, 23 Jul 2004 11:14:02 -0400, Bill Tippett wrote:
>
> >It's ridiculous that we have two manufacturers
> >recommending two different connection schemes for such a simple
> thing
> >as a microphone/PTT connection.
>
> Yes, it certainly is. But the reason may be a failure of some to
> understand and appreciate
> "the pin 1 problem" -- that is, the mis-termination of shields
> within equipment. Lots of ham
> gear, including most Ten Tec equipment, suffers from this design
> error.
>
> The proper termination point for ALL shields is the shielding
> enclosure (chassis), NEVER
> the circuit board. When the shield goes to the circuit board first
> and then to the chassis,
> any RF current flowing on the shield (for example, due to antenna
> action) will get into the
> equipment and cause trouble. The mechanism is simple common
> impedance coupling --
> the path to the chassis through the circuit board has inductance,
> and the voltage drop
> across that inductive reactance gets imposed on various points in
> the circuit that are
> dependent on layout of the circuit board.
>
> Heil's advice to terminate the shield to the connector shell
> suggests an awareness of this
> important issue, and is a good step in the right direction. If this
> causes problems with any
> radio, including the Orion, I would suggest that there is a problem
> with the radio.
>
> Repeat after me -- "You call it a mic cable, but mother nature calls
> it an ANTENNA."
> (Quote attributable to Neil Muncy, ex-W3WJE).
>
> Note that my comments are generic -- I own several pieces of Ten Tec
> gear, but not an
> Orion.
>
> Jim Brown K9YC
>
>
>
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>
>
Duane Calvin, AC5AA
Austin, Texas
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