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black Beauty broad 160-10 Common mode choke
Optimized for best performance across the HF spectrum - best for multi-band antennas
This choke provides an outstanding Common Mode Rejection Ratio (CMRR) across the entire HF spectrum. CMRR varies by band, peaking at 54 dB on 40 meters, and never falling below 41 dB.
This balanced broadband performance is perfect for multiband antennas, especially today's popular EFHW, EFRW, OCF dipoles, multiband verticals, fan dipoles, etc.
All of our products are fully characterized
We measure and publish the performance of our chokes. They are fully characterized, like any industrial electronic component or subsystem. We measure and publish Common Mode Rejection Ratio, Choking Impedance, and Inherent Loss. We also provide honest guidance as to the amount of power that can be used with our chokes.
Many other makes just give a general description or claim. Many makers label their chokes as good for 3kw or 5kw, without any support for these claims. Since most of them are sealed units, i.e. not ventilated, these extravagant claims are unlikely to be true. We have proven this by melting and destroying our competitors' claims at a fraction of their rated power.
In addition, the power limit of a choke is a function of frequency, ambient temperature, and the magnitude of common mode current in the system. This means that any single value stated as a power limit cannot be accurate. The primary cause of power dissipation in a Common Mode Choke is the magnitude of common mode current that it must deal with. Since this cannot be known in advance (it is dependent upon the antennas system), the amount of power that will be dissipated in the choke cannot be known in advance.
Common Mode Rejection Ratio (CMRR)
This choke is designed to provide optimal Common Mode Rejection Ratio (CMRR) across the entire HF spectrum from 1.8 MHz up through 30MHz. This allows it to be used with all-band antennas, wide coverage multi-band antennas, tri-band antennas, or single band antennas for any HF band.
The CMRR curve is presented below.
Inherent Loss
This choke exhibits very low Inherent Loss, which is the dissipative portion of Insertion Loss. Loss is only 0.018 dB on 160 meters and maxes out at about 0.09 dB on 10 meters. This loss is so small that it has no discernable effect on either transmitted or received signal levels.
The Inherent Loss curve is presented below.
Power Handling
This choke will handle up to the full legal limit of 1500 Watts PEP, depending upon frequency and ambient temperature.
It is not possible to determine precisely the maximum amount of transmitted power that a Common Mode Choke can handle based only on the characteristics of the choke and the amount of power transmitted. This is because the antenna system in which the choke is used determines how much of the applied power comes back to the choke as common mode current.
Check the Power Guideline charts here.
The components we use in this choke can handle 2600 Watts of transmitted power without any problems. However, the temperature of the ferrite core will actually limit the amount of power you can use without damaging the choke. That temperature is a function of the choking impedance of the choke, the magnitude of common mode current generated by the antenna system, the SWR of the antenna, and the location of the choke along the feedline relative to the standing wave current peaks. These are specific to each installation and so cannot be completely determined in advance.
Some portion of the common mode current generated by the user's antenna system is dissipated in the choke due to core loss. The more common mode current that a particular antenna system generates, the greater the power that will be dissipated by the choke. You can think of it as "how hard the choke has to work" to suppress the common mode current.
The amount of power that a Common Mode Choke can handle is almost always limited by how hot it gets. This, in turn, is greatly influenced by how well the enclosure can get rid of heat. This characteristic is called "thermal resistance", which is expressed as the number of degrees that the temperature will rise inside the enclosure for each Watt of power that the choke must dissipate.
For this reason, Watts Engineering chokes are ventilated. This allows air to flow over the ferrite core, cooling it dramatically. This ventilation allows our chokes to dissipate about 80% more power than comparable chokes in sealed enclosures. Notice the 7/8 inch diameter ventilation holes along the bottom of our chokes. Screens keep the bugs out.
How much power can our chokes handle? About 80% more than anybody else's!
The bottom line on power handling is the temperature of the ferrite core in the choke. Measure this temperature by looking up through the ventilation holes on the bottom of the enclosure with an IR temperature measuring device, such as an IR temperature gun or an IR camera. If the temperature inside the choke exceeds 180F, reduce power or make some changes to the antenna system to mitigate common mode current and/or reduce SWR.
We provide fairly extensive guidance as to the amount of power that one can expect to use with the choke as a function of operating mode and ambient temperature.
Learn more about Power Handling Ability of Common Mode Chokes
This choke is designed to provide optimal CMRR over the entire HF spectrum, from 1.8 MHz to 30 MHz.
The purpose of a Common Mode Choke is to reduce, or eliminate, common mode current flowing on the shield of coax feedline. It does this by presenting a high impedance to the common mode current, which "encourages" that current to flow into the antenna instead of back along the coax shield. How well it does this is measured as the Common Mode Rejection Ratio (CMRR).
For example, this choke has about 54 dB CMRR on 40 meters. This means that only about 0.2% of the common mode current will be allowed through the choke onto the feedline shield. Which is outstanding.
Without a Common Mode Choke, the majority of the common mode current that flows on the shield of the coax feedline is conducted onto it because the shield is connected directly to one "leg" of the antenna. Placing a Common Mode Choke at the feed point "breaks" that connection and stops the common mode current from flowing on the coax shield. The choke "isolates" the feedline from the antenna.
Connecting the shield directly to one "leg" of the antenna also makes the shield part of the antenna. This affects the gain, pattern, impedance, tuning, and efficiency of the antenna. A Common Mode Choke placed at the feed point preserves that antenna's "native" characteristics by isolating the coax shield from the antenna.
In addition, some of your transmitted signal is picked up by the coax shield, inducing common mode current on the feedline between the feed point choke and the rig. This current will make its way to the shack where it can cause additional RFI. Placing a second Common Mode Choke near the rig, perhaps just before the coax enters the radio shack, is preferred because it will block this common mode current and further reduce RFI and received noise.
RFI and Noise
Common mode current on the coax shield is undesirable because it causes several problems:
It reduces the current in your antenna, which reduces your signal level on both transmit and receive.
Common mode current flows on the outside of the coax shield and radiates. This radiation interferes with your main signal, altering the antenna intended radiation pattern.
This undesired radiation from the coax shield also brings your signal into your house and causes RFI with various electronic devices.
Local noise is also picked up by the coax shield and becomes common mode current. Without a choke at the feed point, this noise is conducted directly onto one leg of the antenna and straight to your receiver, raising your receiving noise floor.
This noise also travels along the coax into your shack, where it is connected to the chassis of your rig as well as everything in between, such as coax switches, SWR meters, tuners, power amplifiers, etc. It radiated into everything in the shack.
The cure is to place a second Common Mode Choke in the feedline near the rig, usually just before the coax enters the shack or the house.
Common Mode Chokes increase signal levels, preserve antenna radiation patterns, stop RFI and reduce received noise.
Inherent Loss is that portion of your signal that is dissipated as it passes through the choke.
Inherent Loss is the fraction of Insertion Loss that dissipates power and generates heat. We care about Inherent Loss because it contributes to heating of the core.
For this broadband choke, Black Beauty "Broad" 160-10, worst case Inherent Loss is only about 0.09 dB at 30 MHz, or about 2%. Best case is on 160 meters where the loss is only 0.018 dB, or about 0.4%. The Inherent Loss plot above tells the whole story. Note that the Y axis of this chart is in milli-dB (one thousandth of a dB).
The Inherent Loss of our chokes is so small that it does not have any discernable effect on signal strength, either for receiving or transmitting.
However, this loss can contribute to heating of the choke. The temperature of the choke ultimately determines the maximum amount of power that the choke can handle. This is why Inherent Loss is important.
Click the button below and to the right to examine the The Power Limitation curves, or click here.
What causes Inherent Loss?
The Inherent Loss of the choke is caused by the coax used to wind the choke. It also includes any loss in the coax connectors but this is negligible.
One way to think about this loss is to envision three or four feet of coax added on to your coax feedline. If the feedline is 100 feet long, adding the choke is roughly equivalent (from an Inherent Loss perspective) to adding three or four feet of coax to the feedline. Inherent Loss is the resistive loss in that short piece of coax. That's it.
The coax used in this choke is very low loss, almost certainly lower loss than the feedline itself. So, from the standpoint of its effect on your signal, Inherent Loss is negligible.
What makes Inherent Loss matter is that the coax in the choke is wrapped rather tightly around a ferrite core. This concentrates whatever heat is dissipated in that section of coax into a small space. The temperature of that coax section will rise more than would a comparable length of straight coax out in the open - simply because the straight piece is spread out and cooled more efficiently.
black beauty "broad 160-10 Max power by band and duty cycle
Run 1500+ Watts PEP at the choke on any HF band as long as the ambient temperature is <120F.
Limit PEP power at the choke to 1400 watts on 10 meters on a 130F day
black beauty "broad 160-10 Max power by band and duty cycle
Run full power on 160 and 80, and also on 40 as long as the ambient is <100F
Limit use of 1500 Watts PEP at the choke to cool days or the lower bands
black beauty "broad 160-10 Max power by band and duty cycle
Run full power on 160 and 80. Also on 40 as long as the ambient is <80F
Limit PEP power at the choke on the other bands based on ambient temperature, as shown
black beauty "broad 160-10 Max power by band and duty cycle
Run 1500 Watts PEP at the choke on 160. Also on 80 as long as the ambient is <95F
Limit PEP power at the choke on the other bands based on ambient temperature, as shown