Antenna Noise Canceller?

[tsmwebb]

I'm looking at this http://www.timewave.com/support/ANC-4/anc4.html as a way of helping null out local rf noise (compressor/alternator/micro-controller &c) on my HF (SEA 235). On paper is seems to me to be a good idea and we do have a local noise problem when underway. But, I don't know much about RF so I could easily be wrong... Anyway, would love to have any thoughts on this or other solutions to RF noise problems. Thanks!

--Tom.

 

[Don S/V ILLusion]

I have no direct experience with this suppression network but it may help you make a better decision to understand what kind(s) of noise you are trying to eliminate. The one you attached in the link may be effective at reducing radiated noise. What you may be experiencing,however, is conducted noise for which this may no nothing.
Before you buy anything which may be useless depending on your situation, it is my suggestion you first identify what type noise it is and from where it is occurring.

 

[tsmwebb]

I have no direct experience with this suppression network but it may help you make a better decision to understand what kind(s) of noise you are trying to eliminate. ...

Thanks. Good point. My main concerns are with:

Ample Power Energy Monitor/Controller -> Produces data chirps near 2k. Radiant (I think).

Alternators -> Pulsing and static all over AM/HF bands. Mix of Conduction and Radiant?

Compressors -> AC noise on HF (I believe radiating from AC motor drive).

Inverter -> AC line nose.

Fans -> spark noise from commutators?

The current "fix" is to turn as many of those things off as I can. But this can be very inconvenient and for some things impractical. I do have chokes an just about every wire in the HF system.

--Tom.

 

[Don S/V ILLusion]

Tom
Sounds like you have both. The ferrite chokes should minimize the conducted noise and I've read good things about the Timewave suppressor you may want to check out yourself on eham.com. Experience tells me neither are 100% effective on weak signals but like I said, I've never tried this one. As they say, it has a by-pass switch so "It can't hurt"

 

[Don12364]

Seems to me that the secondary antenna will collect the required signal plus the interfering signal in roughly the same proportions as the main antenna.

Thus feeding this composite signal in amplified form and 180° out of phase will also attenuate the required signal by a similar amount.
Okay so the interference is likely to be in the near field of both antennas but I doubt this unit will be an effective cure.
I suggest enquiring from the makers as to how it can handle this type of problem.

 

[tsmwebb]

I've read good things about the Timewave suppressor you may want to check out yourself on eham.com. ...

Thanks for that! I will check them out.

--Tom.

 

[tsmwebb]

Seems to me that the secondary antenna will collect the required signal plus the interfering signal in roughly the same proportions as the main antenna.

Interesting point. There has to be some attenuation of the desired signal... But, it makes some sense to me that a relatively poor HF antenna placed very near the QRM will pick up mostly QRM and only a little signal... I'm thinking the QRM is pretty weak and probably goes from a high S number to below QRN in a matter of a few meters. So placement of the antenna for picking up the QRM might well make a big difference... But, I well could be wrong...

--Tom.