Choke / Line Isolator 400w

Choke / Line Isolator 400w
Choke / Line Isolator 400w Choke / Line Isolator 400w
Brand: Ham Goodies
Product Code: HF-ISO4
Availability: 3
Price: £45.00

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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 using RG142 coax on an FT240-31 core, this Choke offers resistive performance 3.5MHz up to 30MHz - Much more effective than an "ugly-balun" made from 20ft of RG58 around a bottle/pipe!

160m/80m : If you intend to use this Choke mostly below 15MHz, we can supply it with 12 turns instead of the usual 8. This gives improved choking performance on the lower bands but it can still be used across the whole of HF.

Picture 3 shows the inside of a similar model, the Doublet/G5RV Choke which has the same core/coax, but screw terminals rather than an SO239 connector.

  • FT240-31 core, RG142 PTFE coax - 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
  • 8-turns: >2k-ohm choking across 1.8-30MHz , 12-turns: >4k-ohm below 10MHz
  • SO239 connectors for "in-line" use
  • Sealed with potting-compound - fully weather-proof
  • 120x80x40mm
  • Weight 585g
  • PDF Guide - 1:1 Line Isolator

Made (and used) by us - Be wary of any supplier who can't (or won't) tell you what's inside the box you buy!

Choosing a Balun
We are often asked "what balun should I use?" by customers - here's our simple guide to choosing the right one:

  • Resonant dipole, coax-fed - 1:1 Choke Balun (we have 100w and 400w versions)
  • Doublet fed with ladder-line - 1:1 Choke Balun or 4:1 Current Balun (most times, a 1:1 is preferable)
  • Random/long-wire down the garden (or up a pole) - UnUn, 9:1 is the common ratio, but our model offers 4, 9 and 16:1
  • Choking Coaxial Cable - 1:1 Line Isolator
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