[TenTec] Orion and TVI

Thu Apr 28 23:40:07 EDT 2005

Giuseppe:

First of all no one loves Ten-Tec more than I do and few for as long as 
I have. While some may choose to argue the following point it has been 
my continuous experience that the majority of Ten-Tec transceivers that 
I have owned (and those that I still do) have all demonstrated RF 
sensitivity issues to one degree or another.... as least when compared 
to other brand transceivers that I owned at the same time. As a 
consequence I have learned to pay close attention to my station's 
equipment interconnections to minimize the possibilities or accidental 
RF pickup on the leads to and from the transceivers.... and do my best 
to have an effective RF station ground.... keep my antennas as far as 
practically possible from my station (not always an easy thing to do). 
With all this in mind I have 'cleaned' up my station so my Ten-Tec 
transceivers are happy now. While I have yet to buy an Orion (you lucky 
fellow)... I had a Jupiter, an Omni-C, and a 540.... and I still have an 
Omni-VI Plus, Paragon, a Century 21, and two Scouts.

And with some relevance to your situation I also have a TS-940SAT (one 
of the aspects I like most about it is its far greater immunity to stray 
RF pickup and its very clean internal AC power supply).

If you are experiencing TVI issues and you have only switched 
transceivers from the Kenwood to the Orion and you are not over-driving 
the Orion's mic circuits (or running a nasty impedance mismatch there) 
it is my suspicion that RF is getting into the Orion. Temporarily 
simplify your rig to antenna setup to the absolute minimum to see if 
this reduces the TVI problems. Be sure your power supply has RF filters 
on the AC input and that there are RF suppressors on the output as well 
(appropriate ferrite beads can do a decent job there). In my environment 
it seems that much of my hot RF issues come from equipment connections 
to the house AC main.

I did the following at my station when I installed my 'very rf 
sensitive' Jupiter last year:
1.  Multiple ferrite beads (appropriate mix) on all power and signal 
lines to the Jupiter and the computer connected to it. Eventually all 
devices somehow sharing a common signal path.... even signal ground 
ended up having ferrite beads on them, but by far the ones that had the 
greatest impact were on the Jupiter, its external power supply and the 
station computer.
2.  Most equipment share the house safety ground via the third prong AC 
ground. This is NOT the RF ground.
3. The station RF ground (station on second floor) connects to the 
station antenna tuner ground only. This ground is via a piece of RG-213 
with the center and shield connected together at the ground rod and ONLY 
the center connector fastened to the antenna tuner (knowledgeable RF 
engineers know why I did this).
4. I do not have additional ground straps in the station other than from 
the transceiver's external power supplies and their associated 
transceivers (minimize DC voltage drop).
5. I have isolating 1:1 current baluns installed at the antennas and I 
use RG-213 or better coax everywhere.
6. Oh, yes I DO have a very nice Nye Viking lowpass filter directly 
after the transceiver (err after the Centaur actually). The additional 
minimum signal loss is easily forgiven for the extra peace of mind 
provided by an additional 40-80 dB of reduction to transmitted harmonic 
and other out-of-band signals.

One last thing to consider... once again your Orion's power supply. 
Place an accurate DC voltmeter directly across the DC input connector of 
the Orion and key down at 100 watts. Check what the voltage drops to. I 
have yet to see a Ten-Tec that is very forgiving of any operating 
voltage below 12 vdc. Check the manual to be sure. If your voltage is 
dropping too far this will take the rig out of its design parameters and 
all bets are off on it signal purity. Be sure the power supply has a 
brute force RF filter on its input and that it is grounded to the 
station's common safety ground.

Hope some of this is useful to you.

I had a Triton IV (540) when I lived in Texas in 1976-1980. I loved that 
rig but gosh it was RF sensitive and I felt it all the time. Over the 
years I have learned the smorgasborg of things that add up to pretty 
good operating.

73,
Jerry, KG6TT

Giuseppe Crosta wrote:

>Dear friends,
>
>I would like to submit this question to the group.
>I have used for several years a Kenwood TS940 transceiver and I never cause TVI problems to my neighbour apartments.
>Now since I start to use a new TT Orion rtx all my neighbours note strong TVI during the operation.
>All other equipment are the same: 3 el yagi antenna, power lines, coaxial line and so on.
>No changes in radio shack. I have added only an external DC power supply for the new rig.
>Why TVI starts? What are the possible reasons and the corrections? Have any other ham the same troubles using the Orion rig?
>Thank for your suggestions and help.
>
>Beppe IZ2ABU
>
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