{"product_id":"5kw-icas-quad-core-high-bands-40-10-m-qro-1-1-current-balun-for-verticals-beams-and-rotary-dipoles","title":"5kW ICAS Quad Core High Bands 40–10 m QRO 1:1 Current Balun For Verticals, Beams and Rotary Dipoles","description":"\u003cstyle\u003e\n\/* RF.Guru Shopify article styles *\/\nh2, h3, h4 { font-weight: bold; margin-top: 1.2em; }\nul { margin-left: 1.2em; margin-bottom: 0.8em; }\nul li { margin-bottom: 0.4em; }\np { margin-bottom: 0.8em; }\n.inline-note { color: #8a8a8a; font-style: italic; }\n\ntable { width: 100%; border-collapse: collapse; margin: 0.8em 0; }\nth, td { border: 1px solid #ddd; padding: 6px 8px; text-align: left; }\nthead th { background: #f7f7f7; }\n\n\/* Highlight boxes *\/\n.related-reading {\n  background: #fff8e5;\n  border: 1px solid #f0d78c;\n  border-radius: 6px;\n  padding: 0.8em;\n  margin: 1.2em 0;\n}\n.related-reading b { color: #b26d00; }\n.related-reading a { color: inherit; text-decoration: underline; }\n\n\/* Technical box *\/\n.tech-box {\n  background: #eef6fb;\n  border: 1px solid #c6d9e8;\n  border-radius: 6px;\n  padding: 1em;\n  margin-top: 1.5em;\n  margin-bottom: 1.5em;\n  font-size: 0.95em;\n  line-height: 1.5em;\n}\n\n\/* Complementary note *\/\n.complementary-note {\n  background: #f9f9f9;\n  border-left: 4px solid #b26d00;\n  padding: 0.8em 1em;\n  margin-top: 0.8em;\n  margin-bottom: 1.2em;\n  font-size: 0.95em;\n  line-height: 1.5em;\n}\n.complementary-note b { color: #b26d00; }\n\n\/* Mini-FAQ *\/\n.mini-faq {\n  background: #f9f9f9;\n  border: 1px solid #ddd;\n  border-radius: 6px;\n  padding: 1em;\n  margin-top: 2em;\n}\n.mini-faq h3 { margin-top: 0; }\n.mini-faq ul { list-style: none; padding-left: 0; margin: 0; }\n.mini-faq li { margin-bottom: 0.6em; }\n.mini-faq li b { margin-right: .3em; }\n\n\/* Author bio *\/\n.author-bio {\n  border-left: 4px solid #ccc;\n  padding-left: 0.8em;\n  margin-top: 1.5em;\n  margin-bottom: 0.5em;\n  font-style: normal;\n  font-size: 0.95em;\n  line-height: 1.4em;\n}\n.author-bio b a { text-decoration: none; }\n.author-bio b { font-weight: 700; }\n\u003c\/style\u003e\n\u003cdiv class=\"rf-article rf-lg\"\u003e\n\u003cdiv class=\"complementary-note\"\u003e\n\u003cb\u003eComplementary:\u003c\/b\u003e Stainless Steel (\u003cb\u003eRVS \/ INOX 316\u003c\/b\u003e) Mounting Kit available — use the \u003cb\u003elarge version\u003c\/b\u003e for this choke.\u003c\/div\u003e\n\u003cdiv class=\"complementary-note\"\u003eAll our products are handmade, and fulfilment times may vary depending on order volume. Please allow 2–3 weeks for completion and shipping.\u003c\/div\u003e\n\u003cp\u003eThis is the \u003cb\u003equad-core compact QRO version\u003c\/b\u003e of our broadband choke series — designed for high-duty HF operation using \u003cb\u003efour stacked 2.4″ toroids\u003c\/b\u003e arranged as \u003cb\u003etwo dual-core sections in series\u003c\/b\u003e. It offers outstanding high-frequency isolation, low insertion loss, and robust power handling for both \u003cb\u003eamplifier outputs\u003c\/b\u003e and \u003cb\u003eantenna feedpoints\u003c\/b\u003e. This version is especially meant for \u003cb\u003everticals, beams, and (rotary) rigid dipoles\u003c\/b\u003e, where a mechanically solid direct connection is preferred. The choke is enclosed in a \u003cb\u003eHV-coated polycarbonate housing\u003c\/b\u003e with \u003cb\u003ecustom silicone gaskets\u003c\/b\u003e and a \u003cb\u003edecompression valve\u003c\/b\u003e for long-term outdoor service. \u003cspan class=\"inline-note\"\u003eAll data are measured under load — no simulations.\u003c\/span\u003e\u003c\/p\u003e\n\u003cdiv class=\"related-reading\"\u003e\n\u003cb\u003eRelated reading:\u003c\/b\u003e\u003cbr\u003e\u003ca href=\"https:\/\/shop.rf.guru\/pages\/baluns-in-a-nutshell\"\u003eBaluns in a Nutshell\u003c\/a\u003e\u003cbr\u003e\u003ca href=\"https:\/\/shop.rf.guru\/pages\/why-common-mode-is-the-most-abused-term-in-ham-radio\"\u003eWhy “Common-Mode” Is the Most Abused Term in Ham Radio\u003c\/a\u003e\u003cbr\u003e\u003ca href=\"https:\/\/shop.rf.guru\/pages\/how-much-choking-do-you-really-need-for-rx-and-tx\"\u003eHow Much Choking Do You Really Need — for RX and TX?\u003c\/a\u003e\u003cbr\u003e\n\u003c\/div\u003e\n\u003ch3\u003e\u003cb\u003ePurpose-Built for Heavy-Duty HF Service (40–10 m)\u003c\/b\u003e\u003c\/h3\u003e\n\u003cp\u003eThis quad-core configuration offers \u003cb\u003eexceptional wideband suppression\u003c\/b\u003e and generous thermal headroom. It is ideal at amplifier outputs, station entry points, or directly at the antenna feedpoint to maximize common-mode suppression across the \u003cb\u003e40–10 m spectrum\u003c\/b\u003e. The terminal-based version is particularly practical for \u003cb\u003everticals, beams, and rotary rigid dipoles\u003c\/b\u003e.\u003c\/p\u003e\n\u003ch3\u003e\u003cb\u003eSpecifications\u003c\/b\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cb\u003eCore configuration:\u003c\/b\u003e 4 × 2.4″ toroids (two dual stacks in series)\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eIntended applications:\u003c\/b\u003e Verticals, beams, and (rotary) rigid dipoles\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eAntenna terminals:\u003c\/b\u003e 2 × M6 INOX (RVS316 \/ INOX 316) terminals with Teflon spacers and 2 thumb screws\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003ePower rating (PL-259):\u003c\/b\u003e ≈ 3 kW PEP \/ 1.5 kW CCS continuous\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003ePower rating (N-type):\u003c\/b\u003e up to 5 kW ICAS under 50 Ω load \u003cspan class=\"inline-note\"\u003e(ICAS rating applies to N connector only)\u003c\/span\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eConnector:\u003c\/b\u003e PL-259 \/ SO-239 \/ N-type (N recommended for high-duty use)\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eEnclosure:\u003c\/b\u003e HV-coated polycarbonate, silicone gaskets, decompression valve\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eReference @ 50 Ω:\u003c\/b\u003e Vpk ≈ 700 V, Vrms ≈ 500 V, Ipk ≈ 14 A, Irms ≈ 10 A\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cb\u003eMeasured Performance (Quad-Core, Two Stacks in Series)\u003c\/b\u003e\u003c\/h3\u003e\n\u003cp\u003eMeasured per EMC-standard procedure with controlled common-mode current injection and precision sensing under load.\u003c\/p\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eBand\u003c\/th\u003e\n\u003cth\u003eChoking Impedance (Ω)\u003c\/th\u003e\n\u003cth\u003eImpedance-Equivalent dB (from |Zc|)\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e40 m\u003c\/td\u003e\n\u003ctd\u003e4.85 kΩ\u003c\/td\u003e\n\u003ctd\u003e45.8 dB\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e30 m\u003c\/td\u003e\n\u003ctd\u003e14.21 kΩ\u003c\/td\u003e\n\u003ctd\u003e55.1 dB\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e20 m\u003c\/td\u003e\n\u003ctd\u003e16.63 kΩ\u003c\/td\u003e\n\u003ctd\u003e56.5 dB\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e17 m\u003c\/td\u003e\n\u003ctd\u003e6.39 kΩ\u003c\/td\u003e\n\u003ctd\u003e48.2 dB\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e15 m\u003c\/td\u003e\n\u003ctd\u003e4.51 kΩ\u003c\/td\u003e\n\u003ctd\u003e45.1 dB\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e12 m\u003c\/td\u003e\n\u003ctd\u003e3.35 kΩ\u003c\/td\u003e\n\u003ctd\u003e42.6 dB\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e10 m\u003c\/td\u003e\n\u003ctd\u003e2.73 kΩ\u003c\/td\u003e\n\u003ctd\u003e40.8 dB\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"3\" class=\"inline-note\"\u003e*Impedance-Equivalent (dB) values are computed directly from measured |Z\u003csub\u003eCM\u003c\/sub\u003e| using a 50 Ω common-mode source reference. Real antennas rarely present 50 Ω in common-mode, so these figures represent the choke’s \u003cb\u003eintrinsic suppression capability\u003c\/b\u003e, not the attenuation of a real antenna system. More background: \u003ca href=\"https:\/\/shop.rf.guru\/pages\/why-db-attenuation-specs-on-ham-chokes-are-a-mess\"\u003eWhy dB Attenuation Specs on Ham Chokes Are a Mess\u003c\/a\u003e.\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cdiv class=\"tech-box\"\u003e\n\u003cb\u003ePractical Note — 40 m is Borderline for QRO (But Close Enough)\u003c\/b\u003e\u003cbr\u003e\u003cbr\u003eOn \u003cb\u003e40 m\u003c\/b\u003e this choke measures \u003cb\u003e≈ 4.85 kΩ\u003c\/b\u003e of common-mode impedance. A common “QRO-safe” rule-of-thumb is \u003cb\u003e≥ 5 kΩ\u003c\/b\u003e, so 40 m is \u003cb\u003eborderline\u003c\/b\u003e — but \u003cb\u003every close\u003c\/b\u003e, and typically sufficient in well-behaved installations.\u003cbr\u003e\u003cbr\u003eIf you want extra margin for \u003cb\u003elegal power (≈ 1.5 kW)\u003c\/b\u003e, add a second choke in series at the \u003cb\u003estation (shack) entrance\u003c\/b\u003e: either a \u003cb\u003ewideband 160–10 m choke\u003c\/b\u003e or another \u003cb\u003e40–10 m choke\u003c\/b\u003e. This pushes the total common-mode impedance on 40 m comfortably above the 5 kΩ guideline in most real stations.\u003cbr\u003e\u003cbr\u003e\u003cspan class=\"inline-note\"\u003e\u003cb\u003eSeries stacking tip:\u003c\/b\u003e chokes in series add in \u003cb\u003eΩ\u003c\/b\u003e (Z\u003csub\u003etotal\u003c\/sub\u003e ≈ Z\u003csub\u003e1\u003c\/sub\u003e + Z\u003csub\u003e2\u003c\/sub\u003e). Do \u003cb\u003enot\u003c\/b\u003e add the dB figures. If you want an “impedance-equivalent dB” number, recompute it from the \u003cb\u003etotal\u003c\/b\u003e |Zc| using the same reference as the table.\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cp class=\"inline-note\"\u003eExcellent wideband suppression from \u003cb\u003e40 m through 10 m\u003c\/b\u003e (with very strong performance at 30 m as well). For extended low-band coverage (160\/80\/60), combine this unit with a dedicated low-band choke in series at the feedpoint or station entry.\u003c\/p\u003e\n\u003ch3\u003e\u003cb\u003eMaximum ICAS\/CCS Power Ratings\u003c\/b\u003e\u003c\/h3\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eConnector Type\u003c\/th\u003e\n\u003cth\u003e160–40 m Band\u003c\/th\u003e\n\u003cth\u003e\u003cb\u003e40–10 m Band\u003c\/b\u003e\u003c\/th\u003e\n\u003cth\u003e6–2 m Band\u003c\/th\u003e\n\u003cth\u003eLimiting Factor\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cb\u003ePL-259 \/ UHF\u003c\/b\u003e\u003c\/td\u003e\n\u003ctd\u003e≈ 2.7 kW ICAS\u003c\/td\u003e\n\u003ctd\u003e≈ 1.3 kW ICAS\u003c\/td\u003e\n\u003ctd\u003e≈ 0.6 kW ICAS\u003c\/td\u003e\n\u003ctd\u003eConnector\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cb\u003eType-N\u003c\/b\u003e\u003c\/td\u003e\n\u003ctd\u003e≈ 10 kW ICAS\u003c\/td\u003e\n\u003ctd\u003e≈ 5 kW ICAS\u003c\/td\u003e\n\u003ctd\u003e≈ 2 kW ICAS\u003c\/td\u003e\n\u003ctd\u003eCoax\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cb\u003e7\/16 DIN\u003c\/b\u003e\u003c\/td\u003e\n\u003ctd\u003e≈ 10 kW ICAS\u003c\/td\u003e\n\u003ctd\u003e≈ 5 kW ICAS\u003c\/td\u003e\n\u003ctd\u003e≈ 2 kW ICAS\u003c\/td\u003e\n\u003ctd\u003eCoax\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e\u003cb\u003eInstallation Guidance\u003c\/b\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eInstall at the amplifier output, station entry, or antenna feedpoint for maximum suppression.\u003c\/li\u003e\n\u003cli\u003eThe M6 terminal version is especially well suited to direct connection on verticals, beams, and rotary rigid dipoles.\u003c\/li\u003e\n\u003cli\u003eHorizontal or vertical mounting — the enclosure is sealed and pressure-equalized.\u003c\/li\u003e\n\u003cli\u003eAll ratings reflect conservative real-world measurements under continuous carrier load.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cdiv class=\"tech-box\"\u003e\n\u003cb\u003eTechnical Validation — How We Measure It\u003c\/b\u003e\u003cbr\u003e\u003cbr\u003eAt RF.Guru Lab, all baluns are evaluated using \u003cb\u003eEMC-standard dual-probe common-mode testing\u003c\/b\u003e. One probe injects controlled common-mode current into the device under test, while a second probe measures the resulting CM current at the output.\u003cbr\u003e\u003cbr\u003eThis method reveals the choke’s \u003cb\u003etrue Common-Mode Rejection (CMR)\u003c\/b\u003e under load — not the differential-mode artifacts seen in simple S21 shield-to-shield VNA tests.\u003cbr\u003e\u003cbr\u003e\u003cspan class=\"inline-note\"\u003eTypical VNA fixtures excite the feedline in \u003cb\u003edifferential mode\u003c\/b\u003e, so they do not measure actual CM behaviour. Our EMC method measures \u003cb\u003ereal suppression performance under power\u003c\/b\u003e, matching what happens in tuner-fed and PA-fed HF systems.\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"mini-faq\"\u003e\n\u003ch3\u003eMini-FAQ\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cb\u003eQ:\u003c\/b\u003e What makes this a “quad-core” choke?\u003cbr\u003e— Two dual-core sections in series, doubling thermal overhead and total |Zc|.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eQ:\u003c\/b\u003e What is this version best suited for?\u003cbr\u003e— Verticals, beams, and (rotary) rigid dipoles that benefit from a robust terminal connection.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eQ:\u003c\/b\u003e What antenna terminals does it use?\u003cbr\u003e— 2 × M6 INOX (RVS316 \/ INOX 316) terminals with Teflon spacers and 2 thumb screws.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eQ:\u003c\/b\u003e Can it replace two separate units?\u003cbr\u003e— Yes. For mid\/high HF it equals the performance of two dual-core chokes in series.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eQ:\u003c\/b\u003e What power levels?\u003cbr\u003e— PL-259: ~3 kW PEP \/ 1.5 kW CCS. Type-N: up to 5 kW ICAS.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eQ:\u003c\/b\u003e Best installation point?\u003cbr\u003e— Amplifier output, station entry, or antenna feedpoint.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eQ:\u003c\/b\u003e Are these values theoretical?\u003cbr\u003e— No. All values are measured under load using EMC-standard common-mode probes.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003cp\u003e\u003cb\u003eInterested in more technical content?\u003c\/b\u003e \u003ca href=\"https:\/\/shop.rf.guru\/pages\/subscribe\"\u003eSubscribe to our updates\u003c\/a\u003e for deep-dive RF articles and lab notes.\u003c\/p\u003e\n\u003cp\u003eQuestions or experiences to share? \u003ca href=\"https:\/\/shop.rf.guru\/pages\/contact\"\u003eContact RF.Guru\u003c\/a\u003e.\u003c\/p\u003e\n\u003cdiv class=\"author-bio\"\u003eWritten by \u003cb\u003e\u003ca href=\"https:\/\/on6ure.be\"\u003eJoeri Van Dooren, ON6URE\u003c\/a\u003e\u003c\/b\u003e — RF engineer, antenna designer, and founder of RF.Guru.\u003c\/div\u003e\n\u003cscript type=\"application\/ld+json\"\u003e\n  {\n    \"@context\":\"https:\/\/schema.org\",\n    \"@type\":\"FAQPage\",\n    \"mainEntity\":[\n      {\n        \"@type\":\"Question\",\n        \"name\":\"What makes this a quad-core choke?\",\n        \"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Two dual-core sections in series doubling choking impedance and thermal capacity.\"}\n      },\n      {\n        \"@type\":\"Question\",\n        \"name\":\"What is this version best suited for?\",\n        \"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"This version is meant for verticals, beams, and rotary rigid dipoles where a robust terminal connection is preferred.\"}\n      },\n      {\n        \"@type\":\"Question\",\n        \"name\":\"What antenna terminals does it use?\",\n        \"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"It uses 2 × M6 INOX (RVS316 \/ INOX 316) terminals with Teflon spacers and 2 thumb screws.\"}\n      },\n      {\n        \"@type\":\"Question\",\n        \"name\":\"Can it replace two separate units?\",\n        \"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Yes, for mid\/high HF it matches the performance of two dual-core chokes in series.\"}\n      },\n      {\n        \"@type\":\"Question\",\n        \"name\":\"What power levels can it handle?\",\n        \"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"PL-259: about 3 kW PEP \/ 1.5 kW CCS. Type-N: up to 5 kW ICAS.\"}\n      },\n      {\n        \"@type\":\"Question\",\n        \"name\":\"Where should I install it?\",\n        \"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Install at the amplifier output, station entry, or directly at the antenna feedpoint.\"}\n      },\n      {\n        \"@type\":\"Question\",\n        \"name\":\"Are these values theoretical?\",\n        \"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"No — all values are load-tested using EMC-standard common-mode injection and sensing.\"}\n      }\n    ]\n  }\n\u003c\/script\u003e\n\u003c\/div\u003e","brand":"RF Guru","offers":[{"title":"PL","offer_id":53117845176662,"sku":"2026-F-010-UH-PL-2M6-THUMBSCREW","price":226.0,"currency_code":"EUR","in_stock":true},{"title":"N","offer_id":53117845242198,"sku":"2026-F-010-UH-N-2M6-THUMBSCREW","price":240.0,"currency_code":"EUR","in_stock":true},{"title":"7\/16 DIN","offer_id":53117845307734,"sku":"2026-F-010-UH-716-2M6-THUMBSCREW","price":340.0,"currency_code":"EUR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0605\/4402\/4764\/files\/RFGBalun.webp?v=1776250373","url":"https:\/\/shop.rf.guru\/products\/5kw-icas-quad-core-high-bands-40-10-m-qro-1-1-current-balun-for-verticals-beams-and-rotary-dipoles","provider":"RF Guru","version":"1.0","type":"link"}