From First Questions to First QSOs: Engineering ON3VZ's HF Station
From First Questions to First QSOs: Engineering ON3VZ's HF Station
A compact-garden installation can be a successful first station without turning one SWR trace or first contact into proof of efficiency, safety or universal design.
Kristof, ON3VZ, wanted a serious first HF station in a compact Belgian garden. The result was an IronWave 6 vertical, a non-penetrating ballast frame, 32 installed radials, a planned coax entry, multiple common-mode chokes and an Icom IC-7300MK2. The station made contacts—but the useful engineering lesson lies in what those observations do, and do not, establish.
Safety boundary: this is a documented installation, not a universal wiring, structural or lightning-protection drawing. Wind loading, ballast, roof or surface loading, electrical bonding, cable entry, surge protection, mains filtering and RF exposure must be assessed for the actual site under current local rules. Never defeat protective earth or create an isolated “RF earth” to cure interference.
1. Start With the Site, Not the Antenna Catalogue
The project began with normal first-station questions: where can the antenna stand, what can the radio's internal tuner accommodate, how might nearby photovoltaic equipment affect reception, where should coax enter, and which work belongs to an electrician? Those questions are more valuable than choosing equipment by popularity alone.
The site had limited space, nearby buildings, household electronics and the practical requirement that the installation remain acceptable to the family and neighbours. RF.Guru's at-home installation was carried out by Jonas, RF.Guru's mechanical engineer and designer. That made the first phase an integrated build rather than an antenna dropped beside an otherwise unplanned station.
| Part of the station | Job it is intended to perform | Evidence still needed for a general claim |
|---|---|---|
| Radiator and 4:1 network | Create and transform the antenna feed impedance over the intended bands | Feedpoint impedance, loss, voltage/current stress, pattern and efficiency by band |
| Radials and nearby conductors | Provide part of the RF return and shape the current distribution | Lengths, layout, soil or mounting environment, current distribution and field or loss measurements |
| Coax and chokes | Carry the wanted transmission-line mode and impede unwanted exterior-shield current | Installed common-mode current plus complex choke impedance and temperature by band |
| Entry panel and bonding | Provide a controlled cable-entry and bonding point | Coordination with the building earthing and lightning-protection design, conductors and surge devices |
| Transceiver SWR display | Estimate the match seen at the radio | Calibration, feedline effects and separate evidence for loss, efficiency, pattern, common mode and exposure |
2. The Mechanical Base Is a Site-Specific Structure
The installation uses an industrial-style ballast frame on a 2.5 cm rubber mat. The mat protects the surface and can increase friction, but it does not establish resistance to sliding or overturning. Wind area, mast leverage, ballast mass and position, surface slope and friction, drainage, ice and the load capacity of any roof or platform all enter the calculation.
A non-penetrating base avoids drilling, but “non-penetrating” is not a synonym for “structurally verified.” The safe design must cover local wind conditions and the completed antenna configuration. Periodic inspection also matters because ballast can move, rubber can creep, fasteners can loosen and corrosion can change joints.
In this build, 32 radials connect to the radial plate. That is an installed fact, not a direct measurement of antenna efficiency. Radial count alone omits length, spacing, elevation, soil, conductor resistance, bonding and how current divides into other nearby structures. More radials often reduce loss in a ground-mounted vertical system, but the result belongs to the complete geometry.
The radiator is described as one approximately 6 m marine-grade aluminium tube, 35 mm in diameter with a 2 mm wall, with critical outdoor hardware in 316 stainless steel. Those are useful construction details. They are not independent proof of lifetime or storm survival. Mixed aluminium/stainless joints need appropriate contact preparation, drainage, compatible compounds where specified, controlled clamp pressure and inspection because galvanic and crevice corrosion depend on the actual environment.
3. Connector Weatherproofing Is a Seal System
Collapsible rubber protectors were fitted to outdoor connectors to keep connections accessible for inspection. That can be a clean serviceable approach when the protector fits the cable and connector and sheds water in the installed orientation.
It is too strong, however, to say that one protector is universally better than correctly applied self-amalgamating tape. A durable interface can require several functions: connector torque and strain relief, a primary moisture seal, an ultraviolet-resistant outer layer, drip geometry and a way to prevent water travelling along the cable. The exact connector and product instructions decide the correct stack. Inspectability is valuable, but only if opening the protection does not damage its seal.
Maintenance rule: record the product, installation date and inspection criteria. Look for displaced seals, cable movement, water tracks, corrosion and changes in loss or SWR. “Weatherproof” should describe a verified assembly, not the appearance of one part.
4. Feed Network and Chokes Need Band-by-Band Evidence
The feed area includes a 4:1 network, a short roughly 60 cm PTFE coax section, ferrites and a quad-core choke using two ferrite mixes. Further chokes were installed near the feed area, roughly 8 m along the route, before the shack entry and behind the transceiver.
That layout is the record of this installation; it is not a general four-choke recipe. Exterior-shield current depends on antenna asymmetry, feedline length and route, nearby conductors, grounding and bonding, and choke impedance. A choke has a complex common-mode impedance, ZCM = RCM + jXCM, that varies with frequency, construction, current and temperature. A useful evaluation therefore combines:
- common-mode current measurements at several positions on every relevant band;
- complex choke impedance across those bands, not only a single “dB” label;
- insertion loss and heating at the actual current, power and duty cycle;
- a before/after check of receiver noise, transmitted interference and touch current; and
- verification that required safety and lightning bonds have not been removed.
A choke controls a mode; it does not repair every station problem. It cannot replace protective bonding, surge protection, a suitable matching network, adequate coax, safe separation or RF-exposure assessment.
5. Cable Entry, Protective Earth and Lightning Are Different Layers
The outdoor entry box mounts coax connectors on a 19-inch metal panel. The panel is bonded into the building's protective bonding system before the coax reaches the operating position. Bringing cable shields together at a defined entry can be sound installation discipline and can reduce uncontrolled conductor loops.
That panel bond does not by itself constitute a lightning-protection system. A complete assessment includes the building's earthing arrangement, lightning risk and any existing external lightning-protection system, antenna and mast bonding, conductor routes and cross-sections, separation, coordinated surge-protective devices on every entering service, and the equipment manufacturer's requirements. Parallel paths through coax, PE, data and mains cables must be considered together.
Current Belgian electrical requirements are published in the AREI/RGIE books. IEC 60364-5-54 addresses earthing arrangements, protective conductors and protective bonding; IEC 62305-3:2024 addresses protection of structures and persons in a lightning-protection system. ITU-T K.71 covers protection of customer antenna installations. The applicable national implementation and the site's qualified designer govern the real work.
Do not copy a photograph as a safety design. The conductor hidden from the camera, the building supply system, cable routes, surge devices and local lightning exposure can change the correct solution completely.
6. The Shack Busbar Bonds; It Does Not Absorb RF
A local busbar connects station chassis and required bonding conductors at an accessible point. It can improve organization and reduce accidental daisy chains. It must be integrated with the required protective-bonding system rather than treated as a separate earth.
At RF, conductor length and geometry matter. A busbar or long wire is not automatically a low-impedance broadband return, and current does not obediently choose it instead of USB, audio, control and coax cables. Common-mode current is controlled by antenna/feedline geometry, balanced routing, measured choking and interface filtering while mandatory protective conductors remain intact.
7. Mains Filtering Requires the Exact Part and Installation
Because photovoltaic and other switched electronics were present, a Schaffner AC choke/filter was included in the site's interference-control work. The photograph documents an installed component; the exact part number, circuit position, ratings and before/after noise data were not supplied here.
A mains EMI filter may use line-to-earth capacitors and can contribute protective-conductor or touch current. It also has voltage, current, temperature, overvoltage, enclosure and installation requirements. It should be selected from the exact manufacturer's data and installed by a competent person under the applicable electrical rules. Do not infer a DIY wiring method from this case study.
Interference work should begin by identifying whether energy is conducted or radiated and whether it is differential or common mode. Then measure the noise before and after one controlled change. A named filter is not evidence of a solved problem without that comparison.
8. What the IC-7300MK2 SWR Screens Establish
The following readings were estimated from the radio's SWR display after installation. They are valuable commissioning observations, but they are not calibrated VNA measurements at the antenna feedpoint. Feedline transformation and loss lie between the antenna and the radio, and the display's scale limits precision.
| Frequency | Band | Approximate displayed SWR | Careful interpretation |
|---|---|---|---|
| 7.100 MHz | 40 m | 2.0:1–2.2:1 | A moderate mismatch at the radio; likely within the published internal-tuner matching range, subject to the actual complex impedance |
| 14.210 MHz | 20 m | 1.0:1–1.1:1 | A low displayed mismatch at this frequency |
| 21.225 MHz | 15 m | 1.0:1–1.1:1 | A low displayed mismatch at this frequency |
| 28.500 MHz | 10 m | 1.0:1–1.2:1 | A low displayed mismatch at this frequency |
| 28.900 MHz | 10 m | 1.2:1–1.4:1 | A modest displayed mismatch at this frequency |
| 29.600 MHz | 10 m | 1.4:1–1.5:1 | A modest displayed mismatch at this frequency |
Icom specifies the IC-7300MK2 internal tuner for 16.7–150 Ω unbalanced, described as 3:1 VSWR or less, with 1.5:1 or less tuning accuracy under its stated conditions. The current Icom manual page remains the operating reference. A tuner finding a match does not remove loss or high voltage/current elsewhere in the feed system.
SWR answers one question: how closely the impedance at the measurement plane matches the reference impedance. These screens do not establish radiation efficiency, gain, pattern, radial loss, feedline loss, common-mode suppression, receiver noise, RF exposure or lightning safety.
9. First Contacts Are the Human Milestone
The shack was assembled around the IC-7300MK2 and the completed feed system. Shortly after commissioning, ON3VZ contacted LZ100LZ in Sofia, a temporary station celebrating 100 years of amateur radio, and made it through the pileup. Further 20 m SSB contacts included a reported path into Russia on 14.205 MHz at about 2232 km.
A QSO is the right emotional validation for a new operator. Technically, it depends on propagation, the other station, noise, power, operating skill and timing as well as the antenna. It should be celebrated without being promoted into a laboratory performance test.
10. A Better Acceptance Test for a First Station
- Mechanical: verify ballast or foundation, mast, fasteners, cable strain, clearances and the inspection schedule for the real wind and site loads.
- Electrical safety: have required PE, bonding, overcurrent protection and mains work checked under current rules. Never use RF troubleshooting to justify defeating safety conductors.
- Lightning and surge: document the cable-entry, mast, building earthing/LPS and coordinated SPDs as one design.
- RF exposure: screen the intended bands, power, duty cycle, antenna geometry and accessible areas, then refine the assessment where required.
- Match and stress: measure impedance over each operating segment and verify the radio, tuner, feedline and network ratings under the worst intended mode.
- Common mode: map exterior-shield current along the feedline on each band, alter one choke position at a time and remeasure.
- Noise: record receiver noise with suspected household sources on and off, then test filtering or bonding changes one at a time.
- Thermal: inspect feed networks, chokes, connectors and filters during a representative transmission duty cycle.
- Documentation: save measurements, photographs, part numbers, torque or installation notes and maintenance dates.
Planning a home HF installation? RF.Guru can help translate site constraints into an antenna and station plan. Treat the result as a project with measurable acceptance criteria—not as a box of parts or a promise based on one SWR reading.
11. Maintenance and the Next Low-Band Phase
The accessible radial plate, panel-mounted connectors, visible chokes and openable entry box make inspection practical. That is a real design advantage. It still needs a schedule: examine clamps and mixed-metal joints, reseal or replace weather protection as specified, look for water and cable movement, retorque only where the manufacturer permits it, and compare measurements with the commissioning record.
A separate low-band solution for 40 m and 80 m is planned. That deserves its own site analysis because conductor length, return-current geometry, pattern, ground loss, voltage and the desired balance between local/NVIS and lower-angle paths differ from the higher-band vertical case.
Primary References and Product Data
- Icom IC-7300MK2 official product specifications
- Icom IC-7300MK2 manual download page
- Belgian FPS Economy: current AREI/RGIE publication
- IEC 60364-5-54: earthing arrangements and protective conductors
- IEC 62305-3:2024: physical damage to structures and life hazard
- ITU-T K.71: protection of customer antenna installations
Mini-FAQ
- Do 32 radials prove high antenna efficiency? No. They document the installed radial count; efficiency also depends on radial geometry, conductor and connection loss, soil, nearby structures and current distribution.
- Does a low SWR prove that the antenna radiates well? No. SWR describes match at the measurement plane, not efficiency, gain, pattern, common-mode current or RF safety.
- Does an internal tuner remove feed-system loss? No. It transforms the impedance presented to the radio; loss and electrical stress elsewhere in the system remain.
- Why use several common-mode chokes? Use multiple chokes only when installed current measurements and system geometry justify them. A fixed distance or core count is not universal.
- Is a PE-bonded coax panel a complete lightning-protection system? No. It is one possible bonding layer within a coordinated design covering the building, antenna, cable entry, conductors and surge protection.
- Do the first QSOs validate antenna gain? No. They validate successful communication under those conditions, not a controlled antenna comparison.