Thanks Gary for your detailed report and remedy. I'll consider adding a
general purpose power line filter on my setup. After reading your report, I
thought I'd send out my notes.
I recently purchased a Tripp-Lite SMART1500LCDT. I had no success trying to
eliminate the RFI.
It's very noisy below 20 MHz. It's likely FCC Class A compliant, but that's
not saying much for HF.
With just the unit plugged into the wall and no load devices or remote
control line connected, noise radiates from the unit most notable on
80m-30m. Pressing the Test button temporarily quiets the unit. I learned
that the Battery Charger is on continuously, except during AC line outage
and for a few seconds after pressing the Test button. With the Battery
Charger function off momentarily, all or most of the HF noise below 20 MHz
disappears.
I tried installing two chokes on the AC input line using 2.4 inch #31
toroid, several turns each, and it didn't help. Connecting load devices
does not seem to make the RFI worse. I also tried adding more choke to the
wire that travels from the main circuit board to the battery. There was
already a toroid, but I added another without success. I believe I need to
open the unit back up and add more choke with considerable more turns to the
battery wire(s).
Tripp-Lite suggested moving the UPS away from the antenna, but that's
impactable for my set up (shack is ~ 25 feet from the base of the
telescoping tower. Antenna is a SteppIR db36 height = (23-70 feet)).
Moving the antenna up does help.
I asked Tripp-Lite for ideas, a schematic, or even a simple block diagram to
use for troubleshooting. But, they do not hand out such material, and only
suggested shielding after I told them moving my radio shack wasn't going to
happen..
After choking the heck out of the AC input line with no effect, I came to
the conclusion that the radiator is internal.
I found some basic UPS design information on the net:
http://www.eaton.eu/ecm/groups/public/@pub/@eaton/@corp/documents/content/pc
t_1548681.pdf
It seems the battery charging circuit is also the UPS off-line power
generator when the AC Input line drops. Adding a toggle switch to
temporarily interrupt the battery charging circuit would be nice, but so far
surmised this is difficult especially without a schematic.
Stuck for now.
Dave KD6BZN
-----Original Message-----
From: RFI <rfi-bounces+kd6bzn=gmail.com@contesting.com> On Behalf Of Gary
Johnson
Sent: Monday, November 30, 2020 9:18 AM
To: rfi@contesting.com
Subject: [RFI] RFI Report on Tripp-Lite UPS installations
Here is a detailed report on the installation and RFI mitigation required
for two Tripp-Lite UPS systems, model SU1000RTXL2UA. The basic unit supports
external battery expansion units, which is the main reason we selected it. A
lot of time and expense went into the noise mitigation.
http://www.wb9jps.com/Gary_Johnson/RFI_files/Tripp-Lite_UPS_RFI_Report.pdf
73,
Gary NA6O
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