Inherent Loss

Inherent Loss is the dissipative portion of Insertion Loss.  It results in a portion of signal being dissipated in the choke.  In Black Beauty Chokes, it is the resistive loss of the coax used to wind the choke.

The Inherent Loss of our chokes is very small, quite a bit less than 0.1 dB. Such a tiny amount of loss does not make any discernable difference in signal strength, either on receive or transmit.

However, even this small loss causes some power to be dissipated by the coax that is used to wind the choke. This contributes to heating of the ferrite core, which is usually the limiting factor with regard to power handling ability. This is the only reason Inherent Loss matters.

Inherent Loss is a function of frequency, rising with higher frequencies. Worst case for these HF chokes will always be on the highest frequency used.  

For our broadband choke, Black Beauty "Broad" 160-10, this worst case Inherent Loss is about 0.09 dB at 30 MHz, which is about 2%.  Best case loss on 160 meters, where the loss is about 0.018 dB, which is about 0.4%. The Inherent Loss plot below tells the whole story.  

Black Beauty MAX 80 is optimized for 80 meters, where it has very little Inherent Loss, as the chart below demonstrates.  Inherent Loss on 80 meters is about 0.029 dB, or 0.7%.  This small loss does not limit the power handling ability of the choke on 80 meters.  It means that the average power dissipated in the choke due to forward power (does not includes dissipation due to common mode current) will only be about 4.3 Watts when the incident power is 1500 Watts and the mode is FT8.  It is less on CW and SSB. The magnitude of common mode current, the SWR, and the position of the choke in the standing waves on the feedline will ultimately determine how hot the choke gets.

Black Beauty MAX 160 is optimized for 160 meters, and has very little Inherent Loss, as the chart below demonstrates.  Inherent Loss on 160 meters is about 0.019 dB, which is 0.44%. This does not limit the power handling ability of the choke on 160 meters. It means that the average power dissipated in the choke due to forward power (does not includes dissipation due to common mode current) will be only about 2.8 Watts when the incident power is 1500 Watts and the mode is FT8.  It is less on CW and SSB. The magnitude of common mode current, the SWR, and the position of the choke in the standing waves on the feedline will ultimately determine how hot the choke gets. 

Power limitations are discussed further on the Power page.  

These measurements were made with an SWR close to 1:1.  

SWR greater than 1:1 may increase or decrease Inherent Loss, depending upon where along the feedline the choke is located relative to standing wave current peaks.  One should assume that an SWR greater than 2:1 may cause additional heating of the choke.

In any event, the Inherent Loss is never large enough to have any effect on signal levels, either transmitting or receiving.  We only care about it because it contributes to heating of the choke.