Choke / Line Isolator 400w

A 1:1 Choke/Line Isolator for use across HF frequencies and handles up to 1kW RF power (assuming 1:1 SWR).  Internally, it's just like our 1:1 Balun but with SO239 connectors at each end.  Wound on an FT240 core, this Choke is perfect for your "legal-limit" station and much more effective than an "ugly-balun" made from 20ft of RG58 around a bottle/pipe!

The standard offering is 9-turns on an FT240-31 which is ideal as a general (400-watt) HF solution - But, if you have a specific frequency range for it, you may wish to tweak the spec:

160m-40m : If you intend to use this Choke on a "long Doublet" up to 7MHz, the 75-mix is the best choice. This gives improved choking performance on the lower bands but performance drops off once you get above 10MHz.

160m-20m : If you intend to use this Choke mostly below 15MHz, we can supply it with 12 turns instead of the usual 9. This gives improved choking performance on the lower bands but it can still be used across the whole of HF.

QRO option : For extra power handling, this offers 2x FT240 ferrites with RG142 making the balun capable of 1000-watts continuous. The 2nd picture shows an example Choke/Isolator before the box is water-proofed: 2 cores, RG142 carefully wrapped and secured.

A similar model is also available, the Doublet/G5RV Choke, which is identical inside but offers screw terminals rather than a 2nd SO239 connector.  If you prefer a non-boxed version, we sell it as part of our RG8-mini Patch Leads.

An optional 30cm RG8-mini PL259 patch-lead is also available at a discounted price.

• FT240 core - QRO option is perfect for full UK legal power
• Ideal for use at the base of a resonant vertical
• Use in the Shack to reduce noise pickup from long coax run
• Use before a 4:1 Voltage Balun feeding an off-centre-fed dipole
• 9-turns: >2k-ohm choking across 1.8-30MHz , 12-turns: >4k-ohm below 10MHz
• SO239 connectors for "in-line" use - optional 30cm patch-lead if needed
• Sealed with potting-compound - fully weather-proof
• 125x85x55mm
• Weight 585g