Thanks for the comments, Jim. The problem seems to peak on 20M but can
occur on higher bands as well. The strange thing is that it doesn't usually
occur until I have been operating for five hours or more. Then, it
continues tog et worse for a while until I QRT. I'm trying to isolate the
inputs to the USB Hub to see if I can tie it down to one or two culprits.
It seems to manifest itself in higher power output in the K4, e.g., 150-200W
out which is kinda hard to do with a 1100W rig. That overdrives the
KPA-1500 so I have to turn the power on the K4 down to about 5 watts. I
have a LPA-100 wattmeter in line with the K4//KPA and it seems to confirm
that the power is higher than it should be.
73,
Dennis, K2SX
-----Original Message-----
From: CQ-Contest <cq-contest-bounces+dbmcalpine73=gmail.com@contesting.com>
On Behalf Of cq-contest-request@contesting.com
Sent: Sunday, July 23, 2023 12:00 PM
To: cq-contest@contesting.com
Subject: CQ-Contest Digest, Vol 247, Issue 21
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Today's Topics:
1. Is this still a ham contesting email reflector? (Peter Sundberg)
2. RFI-proof USB Hubs? (dbmcalpine73@gmail.com)
3. Re: RFI-proof USB Hubs? (Katsuhiro Kondou)
4. Re: RFI-proof USB Hubs? (Jim Brown)
----------------------------------------------------------------------
Message: 1
Date: Sat, 22 Jul 2023 18:43:17 +0000
From: Peter Sundberg <sm2cew@telia.com>
To: cq-contest@contesting.com
Subject: [CQ-Contest] Is this still a ham contesting email reflector?
Message-ID: <63C262C507B35A69@ts201-smtpout76.ddc.teliasonera.net>
(added by MAILER-DAEMON@telia.com)
Content-Type: text/plain; charset="us-ascii"; format=flowed
Or is it a general forum about hotels, DoD bookings, baseball scorebords,
sound systems and God knows what else..?
Come on...!
Peter SM2CEW
------------------------------
Message: 2
Date: Sat, 22 Jul 2023 19:20:39 -0400
From: <dbmcalpine73@gmail.com>
To: "'cq-contest'" <cq-contest@contesting.com>
Subject: [CQ-Contest] RFI-proof USB Hubs?
Message-ID: <041101d9bcf3$20e28050$62a780f0$@gmail.com>
Content-Type: text/plain; charset="us-ascii"
As the number of USB ports I need increases, so does the size of the USB
hub. As the USB hub increases, so does the RFI. I have snap-on cores on
all cables into the USB hub, but it doesn't seem to matter. Anyone got
suggestions for a good reliable bullet proof USB hub, preferably 8 ports,
Vs. 3.0?
Thanks,
Dennis, K2SX
------------------------------
Message: 3
Date: Sun, 23 Jul 2023 09:53:45 +0900 (JST)
From: Katsuhiro Kondou <kondou@voyackey.net>
To: dbmcalpine73@gmail.com
Cc: cq-contest@contesting.com
Subject: Re: [CQ-Contest] RFI-proof USB Hubs?
Message-ID: <20230723.095345.1253922450422828684.kondou@voyackey.net>
Content-Type: Text/Plain; charset=us-ascii
In article <041101d9bcf3$20e28050$62a780f0$@gmail.com>,
<dbmcalpine73@gmail.com> wrote,
on "Sat, 22 Jul 2023 19:20:39 -0400";
> As the number of USB ports I need increases, so does the size of the
> USB hub. As the USB hub increases, so does the RFI. I have snap-on
> cores on all cables into the USB hub, but it doesn't seem to matter.
> Anyone got suggestions for a good reliable bullet proof USB hub,
> preferably 8 ports, Vs. 3.0?
My USB hub had similar issue, and I started to use StarTech ST1030USBM since
then. I have never experienced RFI through USB hub since then.
--
Katsuhiro Kondou, JH5GHM
------------------------------
Message: 4
Date: Sat, 22 Jul 2023 22:35:12 -0700
From: Jim Brown <k9yc@audiosystemsgroup.com>
To: cq-contest@contesting.com
Subject: Re: [CQ-Contest] RFI-proof USB Hubs?
Message-ID:
<087f2ba0-be65-19a3-f902-a572f117b9dd@audiosystemsgroup.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
On 7/22/2023 4:20 PM, dbmcalpine73@gmail.com wrote:
> As the number of USB ports I need increases, so does the size of the USB
> hub. As the USB hub increases, so does the RFI. I have snap-on cores on
> all cables into the USB hub, but it doesn't seem to matter. Anyone got
> suggestions for a good reliable bullet proof USB hub, preferably 8 ports,
> Vs. 3.0?
What bands, Dennis? If HF, I recommend 5-turns through 1/2-in or 3/4-in
#31 clamp-ons on every cable associated with the unit, including the
PSU. Also, try to use a unit that runs on a 12V PSU, so that you can run
it from the 12V bus in the shack (which should use a linear PSU).
Also, make sure that the turns in those clamp-ons are in sequence, not
scrambled. There are photos in one of my RFI tutorials.
73, Jim K9YC
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