Well, it's interesting that this subject has just come up, because I am
in the midst of trying to wire up a D104 to use with the Orion. I got
off on the wrong foot because I didn't have the addendum that corrected
the wiring errors shown in the manual. Since the instructions didn't
make sense to me, I wired it up the way I thought it should work, and my
audio was attenuated, tinny and the PTT had about a 1/2 second delay
before the audio came on. Consequently, I wrote TT service and received
the following reply:
"We are aware that the drawing is incorrect, there is an addendum
included with the manual that states this fact. Audio ground should go
to pin 2 and shield should go to the shell. PTT should be between pin 3
and shell and NOT between pin 2 and 3."
Well, since the shield and audio ground were already connected to pin 2, I
merely connected a short piece of braid between Pin 2 and the connector shell.
There was only slight improvement in the audio quality and the PTT still had a
delay. I haven't gone to the next obvious step and disconnected everything
from pin 2. I'll do that tonight and let you know what happened.
73, Joe
NJ0IP wrote:
Maybe it's not quite so simple, guys.
To be honest, I'm confused.
My first take would have been to tie the mic's "-" to the case ground.
Some of you have suggested that.
I'm suggesting that this is wrong.
One of our BCC contest stations attempted to use my ORION in the recent 160m
ARRL DX contest (SSB) but after 2 hours of failing to get their setup to
work with the ORION, they aborted the plan. They cut the 4-pin mic
connector off, soldered an 8-pin on, and used an FT-1000, Some of you may
be thinking that the hams there didn't know what they were doing, but if you
view their setup which they purpose-built on site just for the contest, and
consider the fact that they set yet another new world record, then maybe
you'll believe me that these were first class hams.
The problem incurred was strong hum and very scratchy audio (when
transmitting).
I had the team forward their exact configuration to me (connection between
the heil headset, the IBM notebook - through an audio line isolator - and
into the front-panel mic jack). I forwarded the drawing to Ten-Tec.
The reply was that this has happened a few times before and been cured by
separating the mic's (-) from the case ground.
With that, I rest my case.
73
Rick
<SNIP>
As to internal grounding, microphone connections and RF, I suspect that
radiation back into the associated equipment or cables is the culprit.
Grounding won't solve it unless one is at the electrical end of a 1/4 wave
or 3/4 wave ground pole. As to inserting a transformer, this is simply a
frequency limiting device (it won't pass RF) so the RF induced into the mike
cable won't get into the rig. I don't advise this approach as impedance
matching, common mode rejection, and associated humm pickup may prevail.
73
Bob, K4TAX
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