Forty-meter Intruder Alert, 23 Nov 2018


Accessed on 24 November 2018, 0430 UTC, Post 780.


Email message from ARRL Pacific Section Manager Joseph Speroni (AH0A).

Comment:  The cause of some interference on 7.040 MHz has been found, and the source has been traced to a Honolulu radio station.  Here’s the report from Joseph Speroni (AH0A):


Happy Thanksgiving to all.  Here’s hoping the holiday was a happy one
with lots of family and friends to share it with.

–       —–

We had a report of an AM broadcast  intruder on our 40-meter band that
appears to be a spurious signal from a Honolulu broadcast station. Tom
(NH6Y) was the first to report it from Maui on 7.040 MHz.  Further
reports from Oahu and Big Island stations confirmed it, some with S7
signal strength.
Our ARRL ASM on Maui, Alan (AD6E/KH6TU) followed up with the Northern
California Contest Club (NCCC).  Several of their members identified the
offending AM station causing the spurious signal. N6IE (Ron) gave us a
detailed analysis of possible intermods that proved to be the cause!  He
even offered a possible location of the signal based on recent FCC
filings. Great engineering detective work!

Merv (K9FD) monitored the signal on Molokai.  He confirmed receipt and
offered an engineering contact that might be able to help.  He had
previous experience with signals caused by intermods from Honolulu
broadcast stations.

Following up with Merv’s contact, we got in touch with  the contract
engineer who confirmed Ron’s analysis.  It turns out the station had
to move its tower out of the way of the Honolulu rail project but could
not complete the transfer in time for the start of rail construction.
They moved the antenna to a temporary tower just out of the way of
construction.  He acknowledge the spurious signal on 7.040 MHz is the
result of a temporary antenna combiner and amplifier.

The short story is that they may try use of a low pass filter to reduce
the signal that may see improvement by December.  The station plans to
move to their permanent tower with a new amplifier and combiner in

The ARRL RFI Lab is aware of the report and is monitoring the actions to
resolve the situation.

Hawaii hams can help by monitoring 7.040 MHz and sending us reports.

–       —–

Follow the Pacific Section on social media for other reports on Hawaii
Amateur Radio.

–       —–

ARRL Pacific Section
Section Manager: Joseph Speroni, AH0A” 

Hawaii Island Amateur/Ham Radio notes:

The Big Island of Hawaii International Swap Meet/Ham Fest will be held on Saturday, 02 February 2019, at the Waimea Community Center, next to the ball field off the Mamalahoa Highway in Waimea (Kamuela).  Doors open to the public at 0930 HST and will close after 1400 HST.  Events include a swap meet, vendor tables, an EMCOMM forum, discussion groups, and VE testing for new or upgraded Amateur Radio Licenses.  For details, contact Steve Miller at

Alan (AD6E/KH6TU) is organizing another online CW class under the auspices of the CW Academy.  Alan says “The class is free…It is a great course..a chance to acquire a new skill with a 1-on-1 instructor.”  The class will be held January to February  2019 using an online video chat format.  The class will meet for eight weeks, “most likely Monday and Thursday at 6 pm HST for an hour each.”  Sign up here:

For the latest Amateur/Ham Radio news and information, please check the blog sidebars and links.  These news feeds are updated daily and weekly.  Thanks for joining us today.

Aloha es 73 de

Russell Roberts (KH6JRM)

Public Information Coordinator

Hawaii County, ARRL Pacific Section

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