Frank,
If you really are having problems with line noise, the best method of
reducing it is with a special external device, specifically designed to
reduce line noise, inserted in the antenna line. It works with any
transceiver.
There are 3 or 4 models of these on the market. I own two - one each from
two different vendors. We use them all the time on dx-peditions where we
often encounter this type of noise, especially on the low bands.
Indeed, in the past few years, guys in my club (The Bavarian Contest Club)
have called me from remote places in the world and had me air-ship the
device to them. Each time they reported satisfactory results. In fact
several returned home and purchased such a device.
The device I recommend you look into is the Timewave ANC4 (Automatic Noise
Canceler and Diversity Combiner). See www.timewave.com
There are others which may be just as good but I have no personal experience
with them.
Here is "their" description:
The ANC-4 is an rf device that eliminates or reduces power line noise, BPL
noise, computer noise, TV-generated interference, and other types of
electrical noise. The ANC-4 unit connects right to the antenna connector of
the receiver or transceiver to cancel locally generated noise before it gets
into the receiver and affects the receiver AGC circuits. Reception of
signals well below the noise level of the local interference is possible. To
cancel locally generated interference, the ANC-4 detects the interfering
signal and adjusts its phase and magnitude so that it matches the offending
interference at the receiver input, but is 180 degrees out of phase,
effectively cancelling the interference. This scheme is particularly
effective at reducing local power line noise or other locally generated
noise types.Front panel controls allow adjustment of both the phase and
magnitude of the local interference, providing extremely deep cancellation
of the offending interference.The ANC-4 connects between the main station
antenna and the receiver antenna connector. A second antenna connects to the
ANC-4 to act as a noise pickup antenna. A short wire antenna or a short
collapsible whip is generally satisfactory for eliminating noises generated
around the operating position or in the house, but an external antenna
usually works better to eliminate noises generated outside the home. Any
noise antenna that works, including combinations of horizontal and
vertically polarized antennas, is satisfactory.The ANC-4 operates as an
active antenna by using the noise antenna and the NOISE GAIN control to
amplify the antenna output. The unit can also be used as a diversity
combiner to peak weak signals or null interfering signals.
Features:
. Cancels S-9 line noise
. Reduces BPL noise
. Nulls strong interfering signals
. Works with any transceiver/receiver
. Makes 2 antennas into phased array
. Wipes out noise before it hits your receiver
. Up to 40 dB Reduction of interference generated by powerlines, electric
motors, TVs and home electronics
. Works for voice, data & CW
. 250 Watt rating
Specifications:
Operating Frequency Range: 500 kHz to 80 MHz (usable down to 100 kHz)
Signal Loss, Main Ant. to Radio: 6 dB RF Input Level, Main Antenna: 3 Vrms
maximum
Maximum Transmit RF Power Through Unit: 250 W PEP or AverageTime to Switch
to Bypass When Transmit RF is Detected: 7 msec, typical
Time to Return to Receive Mode: Approx. 500 msec or 7 msec, typical when RF
is Not Present Internally selectable, (hang time)
Typical Local Noise Types: Power Line Noise, Computer Noise, TV Noise, etc.
Noise Cancellation: Typically 40 dB or greater
Front Panel: POWER switch, POWER LED, PHASE RANGE switch, NOISE PHASE
control, FREQ RANGE switch, NOISE GAIN Control.
Rear Panel: Power Input, Noise Antenna Input, Main Antenna Input, Radio
Output
Input Power: +11 VDC to +16 VDC @ 150 mA, reverse polarity protected
Size: 1.7"H x 6"W x 4.3"D (4.3cm x 15.2cm x 10.9cm)
Weight: 2 pounds (.91 kG)
Temperature Range:
Operating: -20oC to +55oC
Storage: -40oC to +85oC
Humidity: Up to 95% @ +55oC
Xxxxxx
73
Rick, DJ0IP
Munich, Germany
-----Original Message-----
From: tentec-bounces@contesting.com [mailto:tentec-bounces@contesting.com]
On Behalf Of Frank Brady
Sent: Friday, July 22, 2005 11:52 AM
To: tentec@contesting.com
Subject: [TenTec] cw rcvr fundamentals
Greetings to all of you lucky TenTec owners.
I hope this is the right forum for a question I cannot resolve because I
haven't found a way to make an on-air comparison of my TS-140 and FT100D
with a TenTec xcvr.
During a recent contest, while trying to dig VERY weak dx signals out of a
pile of 9+20 contest guns and power line noise, I began to wonder if there
was an affordable (used) rig out there that would do the job.
Problems this (CW only) operator hopes to solve:
With the only two solid state rigs I've owned, if the noise blanker
threshhold is high enough to silence the power line buzz, then a strong
signal almost anywhere on the band chops up the weak signal so bad I can't
copy it.
With my narrow (250) CW filter, the ringing degrades copy almost as much as
it helps.
I know a "notch filter" would be great, but is that an obsolete term with
all of the new DSP enhancements and things like "Roofing Filters" (?)
SO.... my question is:
Is there a whole lot of difference between a "loaded" Omni 5 and the state
of the art Orion when it comes to pulling that weak dx signal out of the
line noise QRN and strong signal QRM?
73 and best of luck to you Orion "1" owners.
Frank W0ECS
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|