[TenTec] Orion Receiver Hints in High Static Conditions

[Len Umina]

I've been spending a lot of time with the Orion Receiver and having a
decent time with it.  I thought I'd share my final configuration for
general use of the receiver along with some commentary on why I set the
controls as I do.

The noise level have been outrageous as the monsoons are within the skip
distance.  If the RFGAIN is at 100, and the preamp is ON the S meter is
solidly 10 over 9 with static crashes to 30 over 9.

PREAMP: OFF  	Most of the time on HF you do not need a preamp.
		This is especially true on 80 meters!  What you
		really need is a better signal to noise ratio
		and most preamps do more harm than good.

NR: OFF		The NR circuit on the Orion defies logic.  The 
		manual says it forms an automatic filter using 
		the DSP to increase the signal to noise, thereby
		providing "noise reduction".  This is not NR,
		and there are better ways to do the same thing
		that actually work.  The big mistake Tentec
		made with this concept is putting the RF Gain
		to max when you hit NR, making it virtually useless
		especially 80 meters.  It might work on 6 but the
		radio does not cover 6!.  Enough rant, just turn it off.

AGC: OFF	Yes, OFF.  You don't need AGC if the radio is
		configured for a high noise environment.  You
		may want AGC on FAST if there is a tremendous
		difference in surviving signal strength.

ATTN: 18 dB	The object here is to reduce the noise coming
		into the receiver to a level somewhere around S1,
		so the 18 dB of attenuation (about 3 S Units) in
		a band running 20 over helps.


MAIN AF: 3/4 scale

		Remember audio gain is primarily clean signal
		gain.  Use it.

RFGAIN: 1	Put the focus on the RF Gain control.  Slowly turn
		it up from zero with no signals present until you
		just barely hear static coming through.  For me
		tonight with an 80 meter windom this happens at 30.

		Carefully increase your RFGAIN until the S Meter reads
		S 1 most of the time.  If you have to go above 60, then
		lower ATTN.  Try to keep the RFGAIN below 60 and the
		S Meter at S 1.

Now tune around the band.  Don't be surprised if you hear lots of things
you never heard before.  Notice that turning the AGC on makes no
difference with the radio running this way.  Use the RFGAIN to
control the speaker level.

Finally, you should have your BW set at 2400 Hz.  This is the point
where the 2400 Hz roofing filter switches in.

Running the Orion this way, I routinely hear stations on the East Coast.
This technique works on 20 as well, and it works on CW and SSB, with the
obvious changes for BW.

What makes the ORION work so much better than my 756 on a noisey band?

It's the roofing filters of course.  A nearby signal is a nearby signal.
Only the ORION has a narrow roofing filter.  The 7800
has a front end that is wide by ORION standards.  Signals in it's pass
band can come from QRM or Lightening, but a signal is a signal.  If it
gets through it's going to have an effect.

In my opinion random signals like strong noise are far more destructive
of front end performance than the simple tests done in the lab to
measure selectivity, especially in DSP radios.  The complex products
have very unpredictable effects on the software and other problems like
insufficient resolution for the algorithm, monotonicity, overflows and
bugs can seriously degrade performance.  In normal situations these
issues might go unnoticed.  Often we just get frustrated and find
something else to do!

The narrow roofing filters help to keep the software operating within
the bounds of a 'normal' band if the gain is set correctly.  Basically,
if you reduce the gain so that the average noise is 0, anything above
the noise should be heard.  Although it may SEEM that the noise is
stronger than the signals when you have every thing in appliance
operator 'preamp on, max out mode' the truth is the radio's AGC is
terribly distorting the truth.  The Orion will show this to you.  Once
the crashes are S1, almost everyone actually has a signal strength above
the noise!  You'll actually see the S  Meter moving from S1 to S8
typically.  In appliance operator mode the same signals appear to be no
stronger than the noise or even less so.

I will warn you of one thing.  When I first started using the ORION this
way, I heard lots of weak DX on 20 Meters CW.  I started calling them
but they didn't hear me.  Finally, when I had to go QRO to be heard, but
once it became clear that I could not only be heard but hear them, I
worked Europe for several hours.  From CA that is FUN FUN FUN!

As I write this I'm listening to K5LDR in Tulsa.  Most of the 6's and
7's have abandoned the band the static is so bad.  He's Q5 S3.  Not bad.

Finally, if you want to add some noise reduction to the ORION I
recommend doing it in the audio after you operate the RX as I've
indicated.  This does help.  I'm now on 3840 and the conversation
sounds like a telephone conference call.  The little noise coming
through on the audio is eliminated by my clear speech noise filter.

73,
Len  WT6G