Not so fast Adam...
I see two 100-ohm resistors from the headphone line tied to both tip and
ring. You may need to excuse Ten-Tec's over-emphasis in warning the user
to use the right plug for the job.
> ----- Original Message -----
> From: "Adam Farson" <firstname.lastname@example.org>
> To: "TenTec Orion Reflector" <TenTec_Orion@yahoogroups.com>
> Sent: Wednesday, April 02, 2003 1:58 AM
> Subject: [TenTec_Orion] FW: [TenTec] Paddle connector / speaker connector
> > I just read the warning in the Orion user manual against inserting a
> > plug in the headphone jack .
> > Please DO NOT PLUG A MONO
> > PHONE PLUG, (two-circuit) INTO
> > ORION's FRONT PANEL PH JACK....
> > A mono plug will short-circuit one of the
> > two audio channels, causing damage to
> > the radio.
> > A resistor in the 100 ~ 220 ohm range in each leg of the stereo
> > jack would protect the audio output stage in the event of an accidental
> > short. The IC-756Pro2 uses a pair of 180 ohm resistors. The engineering
> > for this is "cheap insurance".
> > Best 73,
> > Adam, VA7OJ/AB4OJ