I have second floor station with HIGH power to a vertical, this can be very
difficult for RF Grounding. At first RFI and RF in the shack was terrible
at my QTH.
I would do these two things first,
1). Replace ALL and I mean ALL coax with the LMR-400. Make sure all
connectors are tight, check them a second time by hand and tighten them
again. This alone kicked the but out of most of my RFI problems.
LMR-400 sheild is superior and the losses at HF are very low, Remember,
there are 3 conductors on a coax. Cheaper coax (RG-8 & 213) will let the RF
from the Inner shield and conductor escape to the outer sheild. LMR-400 is
100% film sheilded with a second wire mesh sheild for a very secure
transmission line.
2). Use the Sheilded Ground talked about below. Use a Coax - LMR-400 is
better for this but RG-8 is ok - at the ground rod, connect both Sheild and
center conductor together. At the last item in your shack before it goes to
the antenna ( in my case this is the High Power RFI Low Pass Filter )
connect ONLY the center conductor. leave about an inch of the center
insulating material. Tape up the end to cover and insulate the sheild that
was exposed. Then connect every other RF ground to that point.
I have very very little RF on my cases now and thus have never had my Orion
do any thing weird becarse of RFI. No flickering on my monitors, nothing in
my mic, and nothing going funny in my house.
I would not be in a hurry to buy the line isolators and baluns, At high
power these tend to over heat, They are ok for Low power when the antenna
is at a good SWR.
Best 73's
Rich
K5SF
From: N0KHQ@aol.com
To: k3cc@fast.net, tentec@contesting.com, orion@contesting.com
Subject: [Orion] Re: Orion - Work in Progress
Date: Mon, 13 Dec 2004 11:26:47 EST
Hi Skip,
I understand you frustration with the Orion.
My frustration with SDR's began with the purchase of the Jupiter about 3
years ago.
I know you probably don't want to hear this, but, these rigs are very
susceptible to RFI. If there is any...and I mean any, stray RF in your
shack the
Orion or the Jupiter will find it.
First off, the Orion, like the Jupiter, is nothing more than a computer in
an RF environment inside a transceiver case.
Special RF Grounding and Power Supply precautions must be taken in order
for
the Orion or Jupiter to perform without incident. I know what your going
to
say, "hey, I never had any problems with my other rigs". Well, your other
rigs were not SDR's.
A lot of hams have jumped into the SDR arena without thinking, like
myself,
about what they were getting themselves into. SDR's are the next step in
the
evolution of ham radio transceivers. By the peak of the next solar cycle
you
will see one of the other leading manufacturers of ham radio transceivers
come out with an SDR. It could be Icom, they are in the early stages with
the
introduction of the IC-7800.
All of the top rigs out today, TS-870, TS-950SDX, FT9000DX, IC-7800 and so
on will be referred to as "Boat Anchors", just like we refer to the tube
type
rigs of yesterday as "Boat Anchors". I know all of these rigs work great,
but
there is a time when a product must evolve to the next step. And, SDR's
are
the next evolutionary step in Amateur Radio. Whether you, I, or anyone
else
likes it or not......its coming.
If your dead set on getting rid of the Orion, don't waste your time reading
any further. However, if your willing to give it one more shot......keep
reading.
Firstly, when you hear or read about an Orion owner praising the operation
of their rig, they are not trying to blow smoke up your butt. It's true,
the
Orion is a great rig, and in my opinion, the best rig on the market today
in
any price range.
So, here we go! Please follow these instruction exactly.
1. If your running a balanced antenna, purchase a 1:1 50ohm Bal to 50ohm
Unbal current balun from Radio Works (B1-2K) and install it at the antenna
feed
point. This balun will prevent antenna currents from coming down the shield
of the coax and entering you station and at the same time allow for a
graceful
transition from a balanced system to an unbalanced system.
2. If your running an unbalanced antenna, purchase an RF Balun kit from
Polomar-Engineering and install it at the antenna feed point. For reasons
above.
3. Purchase from Radio Works a T-4 Line Isolator. This isolator will
install
right at the back of the coax connector/s on the Orion. This is a must do.
4. The power for your Orion, I assume, is coming from a DC Power Supply
that
is plugged into a 115vac circuit. This circuit should be a dedicated
circuit
and not shared with other appliances in your home. Appliances in your
home,
depending on their load impedance's are dumping reactive currents onto
your
service neutrals and grounds. The currents are in the milliamp range and
could
create havoc in your power supply depending on how well your power supply
is
capable of filtering the incoming AC.
5. What I do is, the DC power cable going from the power supply to the
Orion
is wrapped around a 2-1/2" toriod donut, 6 turns one direction and 6 turns
the opposite and other direction.
6. One of the biggest culprits is the Orion amplifier keying line. This
line
should be wrapped around one of those 3/4" x 3/4" x 1-1/4" toriod cubes as
many times as possible. RS sells them.
7. Now heres a subject that you may or may not have a problem with: RF
Grounding.
Some hams get a little confused when talking about Grounding for RF and
Grounding for Lightning protection. They are not the same and should be
addressed
separately. Grounding for Lightning protection will do very little for RF
grounding. But Grounding for RF will help with Lightning protection.
Most ham radio books illustrate a typical station grounding system, where
you have this big copper plate or bar behind your station and every piece
of
your equipment is supposed to be grounded to this bar and then a wire runs
from
this bar outdoors to a grounding rod. This illustration is 100% totally
wrong
and does result in the biggest ground loop in the history of Amateur
Radio.
We are talking RF Grounding here and only RF Grounding:
Heres what you do. There should be only one point of connection for that
wire running outdoors and that is at the wing nut on the back of your
antenna
tuner. If you have multiple station grounds disconnect them and thrown
them
away.
>From Ten-Tec purchase a TT-1251 RF Counterpoise Tuner, it comes in kit
form
and will require assembly. I chose the 1251 over the MFJ because the 1251
has
more inductance available.
>From the wing nut on the back of the antenna tuner run a short piece of
copper coated metal plumbers tape (its available from Lowes) to the input
of the
1251, from the output of the 1251 run a piece of RG-8 coax, only the center
conductor of the RG-8 will connect to the 1251 the shield will be removed.
Outdoors, at the other end of the RG-8 connect the center conductor and
sheild together.
This is where you've got to trust me; depending on which frequency you are
having problems with will determine how long you will cut the countrpoise
wire/s.
Lets say that the transmit operation of the Orion gets squirrely on 40 m.
Cut a piece of 14ga stranded insulated wire 20' long (.15 wave length)
connect
one end of this wire to the shorted end of the RG-8, on the other end of
the
14ga wire solder the wire to a 2' piece of 1/2" copper tubing, stretch the
wire out and pound the copper tube into the ground below grass level.
Go back in the house, tune up the antenna tuner for operation on 40m, when
the SWR is as low as you can get it, then move to the TT-1251. First, turn
the
1251 inductor knob for maximum meter reading, then turn the cap knob for
maximum meter reading, then go back to the inductor knob and turn for
maximum
meter reading. The 1251 is simply an antenna tuner for your radial system.
What
you have done here is to resonate the other half of the antenna for
operation
on the exact frequency that your operating on.
Using this system and the above suggestions, I can guarantee you that there
will be no stray RF in your shack to interfere with the operation of the
Orion.
The guys on the reflectors wont see this but:
I am attaching construction details on the RF Tunable Buried Radial System
I
run here at the QTH. Other Ten-Tec Orion and Jupiter owners have install
this
system and are very happy with the results. This information is provided
to
you for your use. If I didn't have this system installed at my QTH, there
is
no way I could try to run the Orion......been there....done that.
In my opinion there are 5 issues that require correcting with the Orion:
1. Monitor Level to low when listening to you transmitted audio.
2. Sweep Display to slow
3. Sweep Display intermittently freezes when in "Sub RX" and you push the
"Sub RX" "NR" or "AN" buttons. This is corrected by rebooting the Orion.
4. The "BW" issue when in CW and tuning from 1000hz to 100hz.
5. "Sub RX" RF Gain quits working below a setting of 32.
Last but not least, documentation and updating of the owners operations
manual.
Ten-Tec has come a long way since the introduction of the Orion a couple of
years ago. You have got to admire the gutsiness of a small group of folks
that
live in the Smokey Mountains willing to risk it all. I support their
efforts
as I'm sure others do in there willingness to take the next step in the
evolution of ham radio transceivers.
I'm posting this information on both reflectors also, I get tired of typing
rather quickly.
Have fun.........and.........dont give up.
Happy Holidays
73
John / N0KHQ / St. Louis
Always on 18.130
Antennas:
You can build 'em better than you can buy 'em
Please visit the sites below:
_http://www.hamuniverse.com/antennas.html_ (http://www.hamuniverse.com/)
_http://www.cebik.com/n0khq.html_ (http://cebik.com/nokhq/html)
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