HF Common Mode RF Choke 1.8 - 30Mhz Line Isolator 1.9K - 7K Choking Impedance

Description

This common mode choke is wound with 12 turns of RG-316 Teflon coax on a Fair-Rite® FT-140 Mix 43 toroid core. The housing is UV resistant PVC with SO-239 connectors on each end.
A compact 7.1 ounce weatherproof 50 ohm common mode choke measuring 2.25" diameter x 3.40" long including the SO-239 connectors.
There are two small weep holes on one end allowing installation in the weather where moisture is likely to enter via inadequately sealed connectors on the coax.  Coax connectors should be wrapped with COAX-SEAL® or some other sealant.
It is also possible for condensation to form due to temperature changes even though the housing and cable connectors are well sealed.  The weep holes prevent that condensation.
Orient the connector end with the weep holes down if the choke will be exposed to rain.
These measurements are taken at the edge of the core.
Resistive from 5.3MHz through 31Mhz: Rs > Xs, resistance > reactance.
Frequency
Rs(ohms)
Xs(ohms)
Zmag(ohms)
1.8Mhz
600
1950
1900
3.5Mhz
1880
2470
3100
5.3Mhz
2811
2644
3860
7.0Mhz
3584
2670
4470
10.1Mhz
4910
2428
5477
14.0Mhz
6412
1422
6569
18.1Mhz
7305
-228
7309
21.0Mhz
7406
-1517
7572
24.8Mhz
6958
-3254
7682
28.0Mhz
6168
-4259
7496
31.0Mhz
5228
-4946
7197
Zmag:
Impedance Magnitude
Rs:
Choking Resistance
Zmag:
Choking Reactance
VSWR:
Less than 1.05:1
Insertion Loss:
Less than 0.15db
A conservative power rating is 200 watts at 3:1 VSWR, higher capability with a low VSWR.
This choke should not be used at the feed point of an end fed half-wave antenna.  In almost all cases, the shield of the coax feeding an end fed antenna is part of the antenna. The coax shield needs to radiate for the end fed antenna to be efficient.
Steve Hunt, G3TXQ, and Jim Brown, K9YC, are well respected authors on the subject of common mode chokes. Their writings are easily found with your favorite search engine. Before you purchase a choke, please spend some time learning about them and whether or not you need one for your station.
Shipped USPS First Class or Priority Mail with tracking.