I had a similar situation on VHF. I operate on 222 MHz among other nose
bleed bands, and was greeted by a very large chunk of RFI in the SSB/CW
portion of 220. Others in northern New England were hearing it too. It
was loudest at my QTH. I identified some of the programming as that of
Channel 11 in Deerfield, NH. So I took to the road with DF gear and
found the problem was coming from the Channel 9 TX in Goffstown, NH.
(WMUR) A call to them brought a quick response. We had a meeting on site
and I demonstrated the problem. They found a bad module in their solid
state Larcan transmitter. It was causing the intermod. The problem was
solved quickly and no government agency got involved.
As a side note, when analog TV was phased out, I ended up getting some
of those same Larcan Hi VHF amplifiers from Channel 9. They make great
222 amps!
73
Dave K1WHS
On 1/7/2023 12:52 AM, Don Kirk wrote:
Hi Frank and gang,
I might be able to help provide some additional insight/direction. This is
not necessarily a case of having to show harmful interference, as the AM
Broadcasters are held to some very stringent spurious emission limits and
the stations actually go through a periodic inspection to show compliance.
If the IMD is being generated within their hardware and they exceed the
emission limits as stated in section 73 of the FCC rules then the station
must address the problem (no need to prove harmful interference to anyone
for it to be a problem that needs to be fixed). If I were in the area I
would try and confirm the IMD is originating from the property of the
transmitter site, and then make an attempt to measure the spurious emission
signal strength relative to the carrier frequency signal strength (an
approximation is fine) to show that the spurious emission likely exceeds
the allowable limits. After achieving this I would then contact the
station general manager to explain the situation including the fact that
ham radio operators over a pretty large geographic area are hearing their
out of band spurious emissions and then have him put you in direct contact
with the chief engineer of the station to look into the problem (this
sometimes requires a lot of digging before you are able to make contact
with the right people).
I have dealt with a few AM broadcast station as well as TV station problems
and the biggest hurdle is getting in contact with the chief engineer, but
after getting in contact with the chief engineer the problem gets addressed
but maybe not at the speed of light as many AM broadcast stations are in
dire financial times and they often don't even have a full time chief
engineer and the chief engineer most likely will not have the skill set to
fix the problem and he will likely need to call in a RF consultant . I
would certainly avoid getting the FCC involved as a first step unless
working directly with the station general manager and chief engineer fail.
This normally does not need to be a confrontational situation as the chief
engineer wants to make sure his station is in compliance. In a recent AM
broadcast station case I was involved with both the part time chief
engineer and RF consultant were hams which made life easy.
Just my opinion based on some past experience.
Don (wd8dsb)
On Fri, Jan 6, 2023 at 10:07 PM Frank W3LPL <donovanf@starpower.net> wrote:
Hello AJ,
Topbanders have done an excellent job of precisely identifying the source
of the 1940 kHz intermod.
I don't think its helpful for those of who are not being harmed to lodge
a complaint with the FCC. Its the responsibility of those being
harmed t file a complaint. Those being interfered with also have a knob
on their radios that allow them to avoid interference.
American amateurs suffering harm can file a complaint to the FCC.
Canadian amateurs can lodge a complaint to their regulatory authority,
that authority can then file a complaint to the U.S. government. It's
a routine process used often.
73
Frank
W3LPL
From: "A J" <iamfromcanadaalso@gmail.com>
To: "Frank W3LPL" <donovanf@starpower.net>
Sent: Saturday, January 7, 2023 1:39:11 AM
Subject: Re: 1940 kHz intruder WWRU WKMD
Hi Frank
How do we define harmful interference?
I know some of the guy's that talk on 1940 and at times it makes it
impossible for them to talk.
One of the gents is located near Barrie Ontario (480 miles) and at times
he can not even hear others he is talking to. Others near Buffalo others in
north west Pennsylvania.
About 380 miles to my location. I had a friend near North Bay Ontario
listen when I was trying to figure out where it was coming from or what
stations it was he is 500 miles away and it is heard there.
I hear it before ~1hr sundown and hear it about 45 minutes after sun rise.
Other times I have heard it mid morning.( signal level from S3 to S9+10
with ~12 db attn)
Is it possible it is re-radiating from some other structure?
Cheers AJ___ VE3HJ
On 1/6/23 19:40, Frank W3LPL wrote:
Hi AJ
In my opinion, the next step is to determine if this intruder is causing
harmful interference,
Several of us can hear it weakly and intermittently hundreds of miles
away,
but so far no one has claimed that its harmful.
73
Frank
W3LPL
From: "A J" [ mailto:iamfromcanadaalso@gmail.com | <
iamfromcanadaalso@gmail.com> ]
To: "Frank W3LPL" [ mailto:donovanf@starpower.net | <
donovanf@starpower.net> ]
Sent: Saturday, January 7, 2023 12:27:47 AM
Subject: Re: Topband: Spur as it reappeared
Hi Frank
So what is the next step?
What do we do?
AJ___ VE3HJ
On 1/6/23 18:44, Frank W3LPL wrote:
BQ_BEGIN
Hi George,
Faulty day/night switches may well be the cause! You may have seen
in my previous email that both stations switch patterns from day to night.
This is the first time I've ever hears of two AM stations with two
antenna arrays sharing the same small site
73
Frank
W3LPL
----- Original Message -----
From: "George Hirst" [ mailto:geohirst@yahoo.com | <geohirst@yahoo.com> ]
To: "Rick Stealey" [ mailto:rickstealey@gmail.com | <rickstealey@gmail.com>
] Cc: [ mailto:wd8dsb@aol.com | wd8dsb@aol.com ] , "donovanf" [ mailto:
donovanf@starpower.net | <donovanf@starpower.net> ] Sent: Friday, January
6, 2023 11:39:10 PM
Subject: Re: Spur as it reappeared
I am “talking through my hat” here. The fact that it seems to suddenly get
much stronger right about your (New Jersey) sunset make me wonder if it is
related to the AM broadcast station(s) changing their antenna pattern(s).
(I haven’t done the research to know if these stations are ones that are
required by the FCC to change their patterns at night to “protect” more
senior stations who share the sane frequency.) Perhaps there is some
corrosion on the RF switches employed in that function that introduces
nonlinearities. Those nonlinearities result in mixing products (ie. 1940
kHz) which are then radiated. ????
George - WF4U
BQ_BEGIN
On Jan 6, 2023, at 4:14 PM, Rick Stealey [ mailto:rickstealey@gmail.com |
<rickstealey@gmail.com> ] wrote:
Note the waterfall. The timestamp on the right is accurate. The
horizontal line is a lightning burst. But notice the ugly signal that came
up on 1940 before the carrier. Anyone have any idea what is happening
there?
<image.png>
_________________
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BQ_END
--
Knowledge is Power and Power is Knowledge.___AJ___1967
Tell me and I will
forget. Teach me and I may learn. Involve me and I shall understand.
___AJ___
BQ_END
--
Knowledge is Power and Power is Knowledge.___AJ___1967
Tell me and I will
forget. Teach me and I may learn. Involve me and I shall understand.
___AJ___
_________________
Searchable Archives: http://www.contesting.com/_topband - Topband
Reflector
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