• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

RFI of a radio amateur on a Naim Uniti 2 amplifier

Douglas62

New Member
Joined
Sep 14, 2021
Messages
1
Likes
0
I have a Naim uniti 2 of the which the speakers are picking up the legal transmissions of a radio amateur 25 metres away. His transmissions are in the 2m/4m/6m and 70cm bands from a horizontally yaggi antenna. We are going to test using a vertically polarise antenna to see if this makes any difference. I wonder if anyone has had similar experiences at all?
All the best to all
Douglas62
 

Jbrunwa

Senior Member
Joined
Mar 13, 2021
Messages
301
Likes
339
Location
Seattle
It is good that the transmitter owner is working with you. 25 meters is pretty close. Technically it is his responsibility to solve the problem, at least in the USA, although I don’t think the FCC enforces this any more. Vertical polarized antenna may not make any difference. Some times RFI enters through cables attached to an amplifier and this can sometimes be eliminated with shielding, grounding, or RF choke ferrite beads that can be placed around the cables close to where they connect into your Naim or other devices. Might not help, but they might have some to try simple shielding.
 
Last edited:

Omar Cumming

Active Member
Joined
Jan 21, 2020
Messages
108
Likes
338
Location
New York
From the Amateur Radio League website at http://www.arrl.org/responsibilities:

Amateur Responsibilities

Let's cut to the chase -- most hams want the answer to one question: "When one of my neighbors has an interference problem, what do the rules say about whether it is my fault or not?" This question is especially important if one of your neighbors raises it. The bottom line is simple: The amateur is responsible for the proper operation of his or her station. This means that all Part 97 rules must be followed at all times. If the amateur isn't experiencing a problem with his own consumer equipment, it's a pretty sure bet that his equipment isn't at fault.

As an amateur, you are directly responsible for interference that results from FCC rules violations at your station. In the RFI world, this means that if your station is transmitting signals outside the amateur band that cause interference to other radio services, it is your responsibility. This is the only specific requirement under Part 97 rules.

The owner of a transmitter which emits spurious emissions, is responsible for making sure that the transmitter meets all technical specifications of the service in which it operates. In the Amateur Radio Service, Subpart D of Part 97 gives standards for amateur transmissions.
Consumer Responsibilities

The consumer is responsible for cooperating with the amateur, the manufacturer and the FCC as a solution to the problem is sought. However, nonamateurs experiencing RFI often don't understand many of the technical concepts that are vital to resolving an RFI problem. When you first start talking about FCC rules with your neighbor, start by talking about what the rules require of you, as a radio operator. At this point, your neighbor will probably be listening, because you are talking about what you must do. You can then explain the other possible causes of interference, show them the actual rules and explain that the rules apply equally to everyone.
In its Interference Handbook, the FCC is very clear in its advice to consumers faced with interference problems. This publication can help get amateurs "off the hook" when the interference isn't caused by the amateur transceiver.

Page 1 of this publication states:

I. Check the Installation of Your Equipment

Many interference problems are the direct result of poor equipment installation. Cost cutting manufacturing techniques, such as insufficient shielding or inadequate filtering, may also cause your equipment to react to a nearby radio transmitter. This is not the fault of the transmitter and little can be done to the transmitter to correct the problem. If a correction cannot be made at the transmitter, actions must be taken to stop your equipment from reacting to the transmitter. These methods may be as easy as adjusting your equipment or replacing a broken wire. These and other simple corrections may be accomplished without the help of a service technician.
Never underestimate the importance of personal diplomacy when you're confronted with an RFI problem.
The way you behave when your neighbor comes knocking sets the tone for everything that follows. No matter what you think of your neighbor, you have to remember that the best solutions are built on cooperation and trust. Knowing all the technical tricks in the book won't do you a bit of good if your neighbor won't even talk to you!
 
Last edited:

DonH56

Master Contributor
Technical Expert
Forum Donor
Joined
Mar 15, 2016
Messages
7,880
Likes
16,666
Location
Monument, CO
Had to deal with this many times over the years, as a back-then novice ham and as a tech. Most of the time ferrite beads would work, though sometimes I had to add RF bypass caps to an input (typically a phono input). Now and then bad interconnects were found, and occasionally the sneak path was actually through the speaker cables (annoying).
 

Jbrunwa

Senior Member
Joined
Mar 13, 2021
Messages
301
Likes
339
Location
Seattle
Had to deal with this many times over the years, as a back-then novice ham and as a tech. Most of the time ferrite beads would work, though sometimes I had to add RF bypass caps to an input (typically a phono input). Now and then bad interconnects were found, and occasionally the sneak path was actually through the speaker cables (annoying).
Yep. Basically, think of your system as a radio receiver, you want your prevent antennas (wires and cables) from receiving the signals, and if you cant, block the signal to your devices and speakers
 

Doodski

Grand Contributor
Forum Donor
Joined
Dec 9, 2019
Messages
21,543
Likes
21,826
Location
Canada
What do you hear? Is it actually his voice?
In the early 1980s I had a Sears stereo system. When I used the turntable and aircraft flights went overhead I could hear the voices of the people communicating. It was like they where right in the room with me.
 
Last edited:

Jbrunwa

Senior Member
Joined
Mar 13, 2021
Messages
301
Likes
339
Location
Seattle
In the early1980s I had a Sears stereo system. When I used the turntable and aircraft flights went overhead I could hear the voices of the people communicating. It was like they where right in the room with me.
:) I recall that aviation bands were typically AM, so easy to understand how that could happen near airports. Although ham vhf and uhf modes are not technically restricted, I think they are mostly FM and these days some digital modes or more rarely SSB. EDIT: maybe some CW on 6M.
 
Last edited:

Jbrunwa

Senior Member
Joined
Mar 13, 2021
Messages
301
Likes
339
Location
Seattle
Wondering how the testing went and if the problem was solved?
 
Top Bottom