Description
CMC-130-3K Common Mode Choke / Noise Suppressor / RF Isolator
This is the one and only Common Mode Choke for 1-30 MHz on the market. It is the only product with over 10,000 Ohms of CMI (Common Mode Impedance) on 3.8-30MHz while maintaining a Resistive part of CMI for more than 25MHz of the frequency spectrum.
- Based on Multi-Zs™ Technology
- Perfect to cure RFI/EMI problems.
- Great noise suppressor!
- Common-mode attenuation is up to ~41dB max. (measured in 50 Ohms systems)
It is a cure for noisy locations, reduce the noise floor of your receiver by several S-units instantly. If you have unbalanced antennas such as OCF dipole or your antennas close to your home, adding one CMC130-3K will greatly reduce RF Interference problems on your equipment and 120/220V wiring inside your home. We do not claim “one size fits all” but actually, we design, measure, and make such products. Our CMC-130K has huge Resistive values of Common Mode Choking Impedance from 1.8-30MHz, click the chart on the side for actual measurement data.
Unlike other companies, we do not claim unrealistic impedance values or frequency coverage. Most important, the value of CMC-130-3K Common Mode Choking Impedance and its Resistive (Rs) part is always higher than the Reactive part (Xs) over the working bandwidth. This parameter, Rs>Xs ensures that our CMC will NOT increase common mode currents as could with inferior coaxial cable chokes.
Only chokes with Resistive (Rs>Xs) CMI- Common Mode Impedance stops and dissipate unwanted RF or noise coming to your equipment for sure.
See the video of CMC’s in action at AC0HF station
CMC-130-3K Features:
- SO-239 PTFE (Teflon®) Connectors which produce no impedance bump but the continuity of coaxial cable where the choke is inserted, helps minimize leakage of RF in multi/contest stations setups.
- PTFE (Teflon®) insulated coaxial cable used can handle a lot more than legal power (1500W) in the USA. It is rated up to 3kW in the HF band.
- The Enclosure is UV stable and could be used outside.
- Multi-Zs™ Technology
| Frq.(MHz) | Zmag(Ohms) | Rs(Ohms) | Xs(Ohms) |
| 1.9 | 7300 | 4450 | 5700 |
| 3.8 | 9900 | 7500 | 6300 |
| 7.15 | 14000 | 13400 | 4200 |
| 10.1 | 14300 | 14200 | 1600 |
| 14 | 13800 | 13800 | -800 |
| 18.1 | 13500 | 13400 | -1600 |
| 21.2 | 13900 | 13700 | -2200 |
| 24.9 | 14500 | 14100 | -3300 |
| 28.5 | 15200 | 14400 | -5000 |
- Zmag-Impedance Magnitude
- Rs-Series Choking Resistance
- Xs-Series Choking Reactance
*ICAS = Intermittent Commercial and Amateur Service
Mike N4EPD –
After trying your CMC-330-1k common mode choke on my KLM KT34A beam, I realized a 3db reduction in noise and decided to try your CMC-130-3K on my all band windom. It reduced my noise level from S7 to S3. I can’t tell how satisfied I am with the quality of your products and the results. Thanks
Mike, N4EPD
Bob Moss W1RAM –
Review for the MyAntenna CMC-130-3K September 2016
I had been plagued by significant RFI noise coming from somewhere in my neighborhood. It got to the point that this “white noise” reached as much as S-8 on 80M and S9+5 on 160, rendering those bands basically useless 24/7. On 40, the noise was often S-6-7 making only the strongest stations being readable. The signal to noise ratio on these three bands was horrible. The utility companies came several times to try to identify the noise source(s) but never with any success. I next tried a Brand X 160-10M Line Isolator and that did nothing. Soon afterward, I saw an ad for the MyAntenna Common Mode Choke CMC-130-3K and decided to give it a try. To my amazement it lowered my noise by 4-5 S-units on 40, 3-4 S-units on 80 and 2-3 S-units on 160. Suddenly, most signals were no longer covered up by the noise. In an instant I could use 160-40M again! So, I decided to get another CMC-130-3K to run in series with the first, one at the end of the 100 ft. coax where it enters my house and the other at the rig’s end. Wow! Now the noise was lowered an additional 1 to 2.5 S-units on these three bands. There was no attenuation of signals that I could detect. While I don’t completely understand how this choke works, I really wish I had discovered it much earlier. Think of all the time I could have saved by not having to walk around the neighborhood with an SW receiver frustratingly snooping for noise. Danny’s Common Mode Choke (CMC) really worked in my case. Instead of hearing mostly noise, now the bands have come alive with signals hidden by that noise. FYI, it did not eliminate other RFI generated by my power supplies and electronic devices, my LG washing machine being the biggest “birdie generator” in my house when in use. But for anyone who has an RFI noise problem similar to mine, I would strongly recommend a CMC from MyAntenna. Danny is super helpful and has always answered my emails with uncommon speed. And when I asked to have the order shipped quickly over Memorial Day weekend, MyAntennas did exactly that! My CMC-130-3K’s gave me three bands back and eliminated a nagging noise problem that I had spent countless hours trying to solve. What’s more, this choke might just be the best “bang for the buck” investment I have ever made in 50+ years of ham radio.
Bob W1RAM
Derwin KC8KQY –
Ok My QTH has power lines along the back property line that feeds the whole street past my house. On the side property line they run to the street that’s north and the one south of me. Just one house over is the BIG boys on steel poles from one sub station to another. SO 40 and 80 had a horrible noise floor. I run a 10 – 80 OFC with a 4:1 balun due to the 100×150 foot lot I have.
WOW..!!! S9 noise floor on 80 dropped to S5 just by putting this in the coax right before entering the shack!!!
40 meters dropped by 3 S Units. 20 meters is also so much better!
Another Ham wrote : ” What’s more, this choke might just be the best “bang for the buck” investment I have ever made in 50+ years of ham radio.”
I have not been a Ham 50 years. BUT Quite simply I CAN NOT AGREE MORE….
I will make note this is not a cure all for all noise. THE STINKING 60 inch Plasma TV in my living room. (THAT I HAD TO HAVE..!! SMH) STILL adds 3 to 5 s units to HF noise floor Depending on band when it is turned on.
A. Bruce K4HK –
Another satisfied CMC-130-3K purchaser here. As others have noted, they don’t eliminate RFI from “wall-warts” and my PC’s VGA cables, but they do attenuate even those common mode noises significantly – from S7 to S1-2 on 20M and S1 on 15 & 10M. The power line noise which was S9 +20 on 80M and S7 on 40M through 10M was reduced to S7, S2-3 and S1 on 80, 40 & 10-20 respectively using 2 CMC-130-3Ks in each coax feedline, one at the antenna switch in the shack and the other at the antenna feedpoint. Also I want to commend Danny for standing behind his products 110% and providing exemplary customer service.
David HC5DX –
I have the CMC-130-3K and it’s a great product. Excellent workmanship as with all his other chokes, Baluns and antenna transformers.
HC5DX
Mike –
Finally a high quality product that works and does not break the bank. Glad to see someone with good business sense, high construction, and good design. Brought my static noise level down by 2 S units. Much heavier than any other RF isolator I have seen or purchased. This is important!!
NEIL MARTIN KS4KY –
This really cleared up a lot of noise for me. Thank you. KS4KY
Art –
Wow! Just received the CMC-130-3K in the mail! Put it in-line to the transmitter and I’m totally blown away!! Nose level dropped off from a constant S5-S7 to less than S2 on 20 meters!!
Really able to hear those signals formerly buried in the noise!! Great job!!
Thanks!!
Chris –
I have 5 of these CMC chokes rigged for 2 antennas. I install them at the antenna feed point and then just before amplifier antenna ports. Also in between the radio and amp. Do this with proper grounding just outside the shack and you have the best setup possible. I have a EFHW with 49/1 UNUN and then this CMC at the feed point. I dont want my 1/2 hardline as a radiator. My counterpoise is wire at 1/4 wave and is perfect. Second antenna is a 43ft vertical. same thing, one at the feed point, another just after the amp. 2 antennas, 5 chokes plus cable gounds and bonded. All RFI is gone, legal limit is perfect, noise level on RX is lowest possible. Verified CMC ratings and are legit. Built well, weather proof…Solid. Chris, AB7BS
Dave –
I have one on my 80-10m 2K. I located it about 50 from the feed point of the antenna and just after my lightening arrestor where the feedline enters the shack. Took 2-3 S-units of noise off my signal. 4 stars due to the price, but I still bought it and would again.
dima.brook –
I use this with my 40-10m EFHW and the noise floor dropped by 2-3 S units! Unbelievable. Great product.
Chris Souris –
I installed one in-line with my all-band vertical, which had an S-5 noise floor on 40 meters. The noise floor dropped to S-0 with a small amount of static pop left. Curious, I installed the second filter in-line with the first and the set sounded like I had disconnected the antenna and the staticky pop is gone. All bands are now much quieter except 160 which has an S-5 noise floor. I have to increase my REF LEV to +7.5db to even see a noise floor on my scope now (Kenwood TS-890S). Definitely worth the money.
Bob K –
Although I do not have any problems with noise I did have a frustrating problem with returning RF shutting down my transceiver. Tried all the usual methods to alleviate the problem without success. Then installed this choke just before the coax enters my house near the ground rod/lightning arrester. RF problem solved.
Roy Westra –
Placed where the feedline of my 80-10 EFHW enters the tuner and dropped the S level from 7-9 to 1-3 on all bands. Outstanding device as is all MyAntennas products, top shelf and I won’t buy from any place else
John G. –
I had no problem with noise but I did have a problem with RF currents on the shield of my coax on both my 40-10 2K and my Cobwebb antenna. I placed both in the shack just before the automatic antenna tuner and now it has a match in 1 sec. Without this choke the tuner would click away for 5-10 seconds. I didnt realize I had an issue with return currents until I tried these chokes. Another quality product from My Antennas.
Alan VK6CQ –
Performs exactly as specified and does the job for me in a high RF noise urban environment. Well designed, well engineered and well worth the outlay if you suffer from high Rx noise or other Common Mode Current problems.
Christopher. K4YAH –
These CMC chokes work exceedingly well. In extreme noise situations you can stack them up, too, helping to mitigate RF noise across the whole spectrum. Like others, we have power lines on the south of our propery line, and being near the beach in Florida, every house has a metal roof. Therefore, RF noise is bouncing around everywhere.
I am considering adding another to the VHF antenna system as well.
Honestly, this product should be listed as an option for every radio or antenna sold by all of the Ham retailers, and in all of their catalogs.
We also have the Myantennas 4010 EFHW. Solid, high quality. We’d get the 8010 but don’t have the physical space with the power lines being so close.
Myantennas.com makes a very high quality product. Buy with confidence.
William Dutton –
Great Product, great service, as always.
Frederick –
I got this to help reduce QRM from all the crap that’s in and around my QTH, I have everything from wall warts, power lines behind the house to several houses close by with solar on the roof not to mention atmospheric noise. After reading other reviews I figured I would try it. It brought down the noise level several S units depending on the time of day and conditions. It’s not a fix all for everything but it helped my received signals more than enough to offset the cost. I got the big one figuring if I run more power in the future it would handle it. Top quality build and solid as a rock.
Gennaro A. –
Perfect. It works well and like declared
Richard Boggs –
Does what it’s supposed to! Fast shipping. Would buy from again…
Ronald Parsley –
Godwin Smith –
Nicely reduced background band noise . I have freq selective noise from my across the street neighbors Solar Panels . They are totally unfiltered Chinese Junk . Any noise reduction is over the top ! I LOVE your 2k plus EFHW . Thank you for a proven engineered product
RANDALL –
Mike W. –
I didn’t know what expect exactly… but this unit has shown consistent value in lowering my receive noise level!
Gerard –
Hi, very pleased with my end fed antenna, yes hf bands are pretty. Much wide open as we get to the peak of the sun cylcle… my end fed is only 45 ft high, I’ve made contacts pretty much around the world.. very happy. Thanks
John Taylor –
Brian McDonald –
Douglas –