[TenTec] Heil ProSet adapter with Orion -- hum

Thu Jun 24 00:27:17 EDT 2004

Lee is probably correct in his ground loop statement.

I had hum on my transmitted signal when I connected my Heil headset with
the Heil / TenTec adapter. I think it was a ground loop since it took
very low power to make the hum appear on the output (monitored through
another receiver).

I made my own adapter and used a short section of microphone cable that
had a shield and two wires.  I connected the shield to the radio end of
the connector and the ground and mic  wires from the connector to the
appropriate pins.

On the 1/8" jack end of the adapter I snipped the shield and taped it to
ensure it did not contact the jack.  I connected the two wires to the
jack and plugged the adapter and headset into the rig.  I connected my
footswitch to the PTT going to the back of the rig through the DIN
connector.

After this I transmitted SSB on 20, 17, 15, 12, and 10 meters using
legal limit power and monitoring via a second receiver.  The hum was
gone on all frequencies but I now noticed that 10 meters had RF feedback
(distorted audio). The hum must have been from the "pin 1 problem" we're
reminded of often by K9YC.

I tried unplugging cables from the interface one-by-one and transmitted
listening to my signal.  When I unplugged the footswitch the problem
disappeared. I plugged everything else back in and the audio stayed
good.

I looked at the footswitch and it was one of the newer Heil ones with
two switches, one for the rig and one for the amp/sequencer/etc.  The
two cords must have made a quite effective 10 meter antenna (my 3
element SteppIR is 35-40 feet straight up here).

I opened up the footswitch, removed the wire and switch that I wasn't
using, wrapped the wire I was using around a ferrite core near the plug
end and transmitted again.

I can now operate 10-20 meters, CW, FSK, and SSB without hearing any
distortion or hum on my signal when using legal limit power.

I can make the hum reappear by connecting the audio in/out leads from
the DIN connector to my computer soundcard without using the interface
box I built (I put ferrite on the audio leads and used audio isolation
transformers).  

It took a lot of empirical testing to figure this out, a matrix on a
sheet of paper helps with trying different combinations until you find
what works at your location. I'd start by trying the adapter wired as
TenTec suggests.  If that doesn't work, try Heil's or the way I outlined
above (I had received suggestions from hams on this reflector). If none
of those three ideas work try unplugging all unnecessary cables
(everything but power, antenna, and mic to begin with).  Try
transmitting and log the results, next add the ground wire, log the
results, etc, etc.

I have connections to right audio out, left audio out, audio in,
footswitch, serial port, cw serial keying interface, fsk, ground, tx en,
tx out, cw paddle, power, antenna, and ground.  I haven't had any
problems with the rig locking up (since I did the audio isolation,
headset adapter, ferrites, etc).  

The audio in each mode sounds good to me through an external receiver
and I have received compliments on my signal. 

I think a large part of the different experiences we are seeing with our
Orions may have to do with our antenna proximity, power output, audio
ground loop (both through computer and mic), as well as the myriad other
accessories we plug into our rigs.

Our ground systems (RF and safety), operating styles, modes, and menu
preferences also affect our output signal.  

There are also probably sequences of front panel button pushing that can
cause some of the bugs or glitches to appear.  I'm not an online
programmer at work but I've seen online program changes that have been
tested by dozens of "beta operators" fail when introduced to 3 or 4
thousand users.  You'll always have a few users enter commands and data
in ways that the programmer doesn't find logical and can't believe
anyone would do.

I'm sure by the time you get as many front panel and menu choices as the
Orion has the software programming required to deal with the
possibilities become extremely complex.

Here's hoping all of us can find a combination of Orion menu/control
settings and station setup that give us a good output signal and stable
operations with no lockups or resets necessary.

73,

George / KF9YR 

-----Original Message-----
From: tentec-bounces at contesting.com
[mailto:tentec-bounces at contesting.com] On Behalf Of Kc9cdt at aol.com
Sent: Wednesday, June 23, 2004 9:59 PM
To: tentec at contesting.com
Subject: Re: [TenTec] Heil ProSet adapter with Orion -- hum

Duane,
My guess is that when you connect the shield to chasis, you are also 
connecting the internal circuit board to chassis ground also. Maybe that
causes some 
kind of ground loop? The circuit in the Orion mnual calls for the shield
to be 
connected to chassis ONLY.
Lee
_______________________________________________
TenTec mailing list
TenTec at contesting.com
http://lists.contesting.com/mailman/listinfo/tentec

---
Incoming mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.707 / Virus Database: 463 - Release Date: 6/15/2004

---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.707 / Virus Database: 463 - Release Date: 6/15/2004