While grounding the mic connector on the Pegasus and adding ferrites may
have helped the Pegasus owner, it is not the right solution when dealing
with these problems on the Orion.... I am referring specifically to
grounding the mic connector... a solution suggested earlier today. What
is ground anyway?
The audio front ends of these two transceivers are completely
different. The Orion uses a balanced audio design as opposed to the
Pegasus more 'amateur traditional' unbalanced approach. The Pagasus
combines the mic- and PTT return on the same pin. Indeed, most Ten-Tec
microphones designed before the Orion had these two signals combined on
pin 2. However, combining these two signals on the Orion can
accidentally configure the Orion's circuitry to make it highly
susceptible to localized RF, while if done per the Orion's manual, the
Orion is incredibly insensitive to surrounding RF fields..
I wrote a long explanation of how may hams can totally eliminate the
apparent RF problems they are experiencing with their Orions by merely
paying proper attention to separating the PTT return ground (which goes
to the Orion's mic connector casing) from the mic- return line. And by
keeping the mic- return line OFF the shield. This is a must with low
impedance microphones (like the Heil series) designed for balanced
signal interconnects. The best design is where there are two twisted
signal lines surrounded by an isolating shield. One of those twisted
wires is the mic+ and the other is the mic-. These go to mic connector
pins 1 and 2 respectively. Study the drawing and explanation on page 10
of the Orion user manual (Revision 3, February 2005). This wiring is not
an option for the Orion 565. The shield around the mic cable must act as
the PTT return with a separate wire (hopefully outside the shield) as
the PTT+. Ten-Tec maintained the traditional four-pin mic connector on
the Orion which made interfacing to a balanced audio input difficult.
The Orion II makes this process much easier to accomplish with its 8-pin
connector.
In my posting I went into pretty great detail of why this wiring is
important and why symptoms of incorrect wiring are far more apparent
using 2.x firmware. So if you want to understand the 'why' behind this
check out that posting. Otherwise, just follow Ten-Tec's wiring diagram
and you will be fine. DON'T assume your mic and its factory cable are
correct. Both my Heil Studio One microphone and the supplied cable had
problems that defeated the balance of the circuit. Once I corrected
those problems and wired the plug to the Orion correctly all the
problems that had me REGRETTING my Orion purchase went totally away.
It boggles my mind how many times the same information circulates on
these reflectors. If you are new to reflectors, there is an Archive site
where you can find probably all the answers to your questions... already
asked and answered. The Archive for this reflector is:
http://lists.contesting.com/_tentec/
If you know about the Archive and aren't using it there is a wealth of
information (and miss-information) to be found. In this Archive you will
find the details of the solution I described above. I did not deduce
this on my own (although I am an EE with years of audio, RF and digital
experience), but rather I had to force myself to not be so lazy and look
for the less obvious probabilities... As a result I found my solution
(with the aid of Ten-Tec and Heil engineering support)... and I believe
it is also the solution that so may are looking for regarding their RF
distortion problems. I did my posting about one month ago I would think.
The solution I detailed is especially true for those using 2.x firmware
with the Orion 565 and any firmware with the Orion II, although the
plug/jack wiring is different.
Good luck,
Jerry, KG6TT
--
Ralph Jerald "Jerry" Volpe
Amateur Radio Operator KG6TT
ARRL Member & VE
FISTS 12304
788 Chestnut Drive
Fairfield, CA 94533
kg6tt@arrl.net
510 325-7724
707 399-8838 FAX
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