black Beauty broad 160-10
Optimized for best performance across the HF spectrum
This choke provides an outstanding CMRR on each of the HF bands, ranging from 48 dB (on 40 meters) to 35 dB (on 10 meters). This balanced broadband performance is perfect for any HF antenna. It is especially well suited to today's popular multiband antennas, such as end feds, doublets, OCF dipoles, and multiband verticals.
All of our products are fully characterized
We measure and publish the performance of our chokes. They are fully characterized, like any other important electronic component or subsystem. A spec sheet is included below and performance curves are provided throughout.
Common Mode Rejection Ratio (CMRR)
This choke is designed to provide the most Common Mode Rejection possible across the entire HF spectrum, 1.8 MHz up through 30MHz. The CMRR plot is shown below.
Insertion Loss
Insertion Loss ranges from .01 dB at 1.9 MHz to 0.06 dB at 30 MHz. This loss is so small that it has no discernable effect on either transmitted or received signals. The Insertion Loss plot is shown below.
Power Handling
There is no one number that can describe the power handling capability of a Common Mode Choke. Such claims are often inflated and, as a minimum, they obfuscate reality. This may occur because the makers do not fully understand or measure their products.
In virtually all situations, the power handling ability of a Common Mode Choke is determined by the temperature of the ferrite core, which is heated by insertion loss.
The temperature of the ferrite core is always a function of the transmitted power, the insertion loss of the choke (which is a function of frequency), the duty cycle of the transmissions and the ambient temperature. It can also be affected by residual common mode current that flows through the choke if it is an ineffective choke. The common mode rejection of our chokes is so high that residual common mode current is rarely, if ever, a factor.
Notice the 7/8" diameter ventilation holes along the bottom of the our choke enclosure. This ventilation keeps the ferrite core cooler and allows the choke to handle about 80% more power than a sealed enclosure. There are bug screens to keep critters out.
This choke can handle as much as 2500 watts on the lower bands with low duty cycles (such as uncompressed SSB). But on 10 meters on a 100° F day while running continuous FT8, the power incident at the choke (after feedline loss) should be kept down to about 1kW. The power limit varies by band, mode, and ambient temperature.
Check out how much power you can comfortably run on each band for any given mode of operation for any given ambient temperature by scrolling down to the Power Limitation curves - down past the datasheet below - or by clicking this button.
Learn more about Power Handling
Click the button below to learn more about what determines the power handling capability of Common Mode Chokes and how to deal with it.
Return and Warranty Policy
We accept returns for any reason, or no reason, for 30 days after receipt. Our products are also covered by a full 2 year warranty. Please see our Terms and Conditions.
Common Mode Rejection (CMRR)
This choke is designed to provide the best CMRR over the entire HF spectrum, from 1.8MHz 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 48 dB rejection on 40 meters. This means that only 0.003981% of the common mode current will be allowed through the choke onto the feedline shield. Which is outstanding.
Common mode current flows on the coax shield 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 impedance, the efficiency, and the pattern of the antenna. A Common Mode Choke placed at the feed point preserves that antenna's "native" characteristics.
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 rig and can also cause RFI. Placing another Common Mode Choke near the rig, perhaps just before the coax enters the radio shack, 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 RFI - your signal interfering with other electronic devices.
It is also undesirable because local noise picked up by the coax shield becomes common mode current flowing on the shield which, without a choke, is conducted directly onto the antenna. This raises the noise level during reception.
This noise will also be conducted directly to the rig, and some portion of it will show up as received noise. The cure is to place a second Common Mode Choke in the feedline near the rig.
Common Mode Chokes stop RFI and reduce received noise - sometimes quite dramatically.
insertion loss
Insertion Loss is a function of frequency. The higher the frequency, the higher the insertion loss.
For this broadband choke, Black Beauty "Broad" 160-10, the worst case insertion loss is 0.06 dB at 30 MHz, which is 1.38%. Best case loss for the same choke is on 160 meters where the loss is only 0.01 dB, or about 0.23%. The Insertion Loss plot above tells the whole story.
The insertion loss of our chokes is very small, quite a bit less than 0.1 dB. Such a small amount of loss does not make any discernable difference in signal strength, either on receive or transmit.
However, this loss can be large enough to cause power to be dissipated by the choke, which causes heating of the ferrite core and the coax used to wind the choke. This heating turns out to be the primary limitation that determines how much power the choke can handle. This is why insertion loss is important.
Click the button below to examine the The Power Limitation curves, or click here.
What causes Insertion Loss?
The Insertion Loss of the choke is caused by the coax used to wind the choke. Any loss in the connectors or the core is negligible.
One way to think about this loss is to envision about four feet of coax added on to the coax feedline. If the feedline is 100 feet long, adding the choke is roughly equivalent to adding four more feet of coax to the feedline. The coax used in the choke is very low loss, almost certainly lower loss than the feedline itself. So, from the standpoint of its effect on your signal, the insertion loss is negligible.
What makes insertion loss matter is that the coax is wrapped rather tightly around a ferrite core. This concentrates whatever heat is dissipated in the coax into a small space. The temperature of the choke will generally rise more than the temperature of the feedline simply because the feedline 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