Wally and all,
Since receiving the SDR-1000 in July 2003 I am fighting the RFI, spurious,
noise and common mode issues and no final and universal solution yet! So far
I try to manage with isolating transformers in I/Q lines (input and output),
ferrite beads in parallel cable as well as the USB to Parallel cable,
strictly a single point grounding system (star configuration) and on top of
all I have a 7.5 kVA UPS system for powering my office/lab/hamshack. IMHO,
these problems are related to the fact that no theoretically "clean" star
groundings can be created and ground loops eliminated, mainly due to the
common practice of connecting together the "Protective Earth" (PE) and
"Signal Earth" already inside the electric/electronic appliances, especially
the PCs.
PLEASE, NOTE! The problems are not alone with the SDR-1000 only. My Yaesu
and Icom equipmet suffer these problems, too, as soon as I connect the PC to
them. Whatever systems I have had, a careful routing of cables,
experimentation with the grounding points, common mode and differential mode
filtering, signal line balancing and shielding were needed.
When it comes to the RFI, keep all radiating wires and cables as far away
from the hamshack as practical. A lot of "wonder" antennas may have
essential part of radiation coming from the feedline - Carolina Windom
included. Sorry Wally, I have no ready made solution for you.
Believe me, all these requires good understanding of the theory, but that is
not enough. Finding the optimal wiring in our wireless hobby is art that
beautifies the science. Who would make the optical fiber interface for our
SDR-1000 so that we don't need to be artists and scientists at the same
time?
73,
Ahti OH2RZ
----- Original Message -----
From: "Wallace Watson" <[EMAIL PROTECTED]>
To: <FlexRadio@flex-radio.biz>
Sent: Tuesday, May 31, 2005 11:54 PM
Subject: [Flexradio] RFI Issues
Greetings All,
I have had my SDR-1000 now for approximately 3 month and find the receiver
very pleasurable to use. New additions are being made to the software for
the radio adding to it's functionality.
My computer is an HP/Compaq Celeron 2.4Ghz with 512Mb of RAM. I initially
purchased a Creative Labs Audigy 2ZS card but I never installed it in the
computer, instead when the M-Audio sound card was mentioned on TeamSpeak
and posted in the forum I decided to purchase and install it instead.
Prior to the Dayton Hamfest I ordered a Behringer UB802 mic
preamplifier/mixer for SSB use vice installing a second sound card in the
computer. I hooked up the Behringer mixer the day I returned home from
the Dayton Hamfest.
I also had switched to using the USB cable for use with the SDR-1000 prior
to this.
I have since begun making contacts on 80 and 40 meter bands on SSB and
experimenting with CW using the automatic memory and keyboard modes with
the SDR-1000 with the 100 watt amplifier. I have been experiencing RFI
problems when I switched to using 30/20/15/10 meters with my primary
antenna system, a Radio Works Carolina Windom. The antenna vertical
radiator terminates immediately overhead my family room which serves as
my ham shack. The RFI problem manifests itself as follows:
When using the USB cable between computer and radio, when I transmit on 30
meters or above the radio begins by transmitting and then I get a High SWR
indication on the display and the radio reverts to the Standby mode. I am
unable to switch the radio back on via the software Standby/ON button, I
must instead disconnect/reconnect the USB cable from the computer or
reboot the computer. I have been semi-successful at reducing/partially
eliminating this problem by reducing output power to approximately 35
watts.
In an attempt to eliminate this problem I switched back to using the
original parallel cable between the computer and radio, with this cable in
place on 30 meters and above I am able to go into transmit at the 50 to
100watt level and the radio will transmit in SSB or CW but will shut down
the 100watt amplifier while in operation, when I come out of transmit mode
to receive the receiver is no longer receiving signals, I must switch off
the radio and back on using the Standby/ON button on the SDRConsole. If I
reduce power to an approximate 35 watt level, the radio functions
normally. I have a second antenna, a tape 40 meter dipole, this antenna
is usable on 40 and 15 meters only. With this antenna I have completely
normal operation on 40 meters and with the Carolina Windom, I have
completely normal operation on 80 and 40 meters.
I have 3 other radios at my location, a Kenwood TS-440S, a Kenwood TS-450S
and an old Yaseau FT-101EX and have experienced no problems on the air
utilizing any of these radios.
I believe my next step is to order and install the Radio Works ground
isolators in the hopes that this will eliminate my apparent RFI/ground
loop problem which are interfering with my operation of the SDR-1000
radio. I have no option to move the Carolina Windom antenna. I do intend
to install an additional multi-band dipole antenna at the boundary of my
residence which is separated from a farmers pasture by a 12 foot security
fence.
My grounding system consists of a 12 foot copper ground rod approximately
1" in width driven into the ground outside my radio shack window. Only 6"
of the ground rod is exposed above ground and I have attached to it via
bolt, lock-washer and nut a 3/4" wide tinned copper flat ground cable
approximately 5 feet long and terminating at my Kenwood manual matchbox.
All radio equipment, including the SDR-1000 radio is connected in a star
pattern to this single grounding point.
Please advise if anyone has suggestions or recommendations for my
installation?
Thanks, Wally (M0ZAZ).
--------------------------------------------------
Wallace Watson [EMAIL PROTECTED]
Croughton RAF Base - United Kindgom
--------------------------------------------------
_______________________________________________
FlexRadio mailing list
FlexRadio@flex-radio.biz
http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
