Intermod would be covered by FCC rules, but whether it would be picked up in
measurements would depend on how the measurements were made and where the
intermod was occurring. There are three likely places -- at either station, or
near the vicinity of affected equipment. Here at W1AW, we have two very strong
local AM stations. If we leave our amplifiers connected to antennas, but
unpowered, they intermodulate the two stations and re-radiate the intermod
locally. Measurements made at either station would not show it, and the
intermod is very low compared to the FCC limits for spurious emissions.
Ed Hare, W1RFI
-----Original Message-----
From: RFI <rfi-bounces+w1rfi=arrl.org@contesting.com> On Behalf Of Jim Brown
Sent: Wednesday, October 27, 2021 3:12 PM
To: rfi@contesting.com
Subject: Re: [RFI] Splatter from AM Radio Station WNTS Indianapolis
On 10/27/2021 6:29 AM, Gary Peterson wrote:
> Every AM broadcast station is required to perform annual measurements,
> searching for these types of problems. I contract to perform spectral
> measurements for most of the AM stations within a 100 mile radius of my home.
> I have the necessary equipment and travel to within approximately 1
> kilometer of each transmitter site. I measure each station’s occupied
> bandwidth, measure harmonics, up through and including the 6th and search for
> spurious signals, below, in and above the broadcast band.
Yes. But do those spectral measurements also include intermod products?
I started out in ham radio in jr high school with two 5kW non-DAs within a mile
of each other and about 1.5 miles from me, on 930 and 1470 kHz producing a
strong product at 3870 kHz. There may have been others products, but that one
gave me a lot of grief.
73, Jim K9YC
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