OR7C/P Field Day 2026: Divide the Work, Keep the Station Predictable
OR7C/P Field Day 2026: Divide the Work, Keep the Station Predictable
One portable antenna should not be expected to deliver every band, every elevation angle and every receive job. OR7C/P will split those jobs across three systems, then let measurements and on-air results—not product labels—decide the final layout.
For OR7C/P Field Day 2026, we are deliberately refusing the usual one-antenna compromise. The planned upper-HF transmit antenna is the DeltaRex closed loop. The low-band job goes to the EFHW16080 end-fed wire. Receive gets its own EchoTracer3 active E-field probe. That is the equipment plan—not a promise that three product names automatically make a good station.
The real design is the installed system: support heights, wire geometry, ground and ballast arrangement, feedline routes, common-mode boundaries, station spacing, filters, switching, interlocks and the noise environment. Each part will be checked on site, and the layout can change when the measurements disagree with the sketch.
The operating split: DeltaRex for planned 40–10-metre transmitting, EFHW16080 for dedicated 80- and 160-metre work, and EchoTracer3 as a receive-only comparison and operating antenna. Day/night propagation determines when each band is useful; it does not certify an antenna.
Upper HF Goes to the Closed Loop
OR7C/P intends to use the DeltaRex on 40, 20, 15, 12 and 10 metres. Keeping that assignment bounded is useful. It leaves the physically large low-band job to a separate wire and lets the loop be installed for the upper-HF paths that matter during the event.
The starting geometry places the lower vertex at roughly 2 metres and the upper span near 7 metres. Those numbers describe a support plan, not an invariant pattern. Changing height changes the direct and ground-reflected field, while soil, slope, nearby conductors, loop shape and feedline current alter the result. A few metres of height cannot be translated into “regional” or “DX” performance without an installed model or field measurement.
We will therefore treat 2 metres at the bottom as the first configuration, record resonance and feedpoint data, inspect exterior-feedline current and compare real contacts. If practical constraints move the lower vertex to 3 or 4 metres, that is a new configuration to measure—not an automatic upgrade or downgrade.
The Low Bands Get Their Own Wire
The EFHW16080 is assigned only the 80- and 160-metre work. The initial field layout uses three 6-metre aluminium supports on ballasted frames, forming a low inverted-L or bent horizontal-L. It is a compact Field Day geometry for a very long wavelength, so expectations on 160 metres must remain honest.
A low wire can make contacts, particularly on paths supported by higher elevation angles, but it is not automatically efficient and its pattern is not defined by the words “inverted-L.” Current-bearing wire close to lossy ground, vertical and horizontal proportions, bends, end height, return path and feedline participation all matter. The 80-metre and 160-metre current distributions are also different, even though the same conductor is used.
If logistics permit, the centre section may be raised to about 16 metres while the outer supports remain near 6 metres. That creates a shallow centre-peaked or inverted-U-like layout. Moving part of the conductor higher changes ground coupling and the vector sum of the fields; it does not guarantee a specific efficiency gain or lower take-off angle. The useful comparison is measured feedpoint behaviour plus A/B/B/A on-air results after restoring the first geometry.
High-voltage wire: an end-fed half-wave has a high-voltage region near its end. Supports, guying, public access and conductor clearance must be designed so nobody can touch or approach the radiator while transmitting. Ballast stability and a clearly controlled exclusion area matter more than a convenient sketch.
The Feedline Is Part of Both Transmit Systems
The loop feed and end-fed feed are different current-path problems. Neither is solved by placing a choke at a fashionable fraction of a wavelength and assuming the exterior of the coax has disappeared.
For the DeltaRex, the matching network handles impedance transformation and a separate current choke addresses unwanted common-mode current. For the EFHW16080, the intended return path, transformer, coax exterior, local ground or counterpoise and choke position interact. In both cases, the field procedure is the same:
- route each feedline deliberately and keep its geometry repeatable;
- measure exterior-shield current at several positions and on every operating band;
- move or add choking only when the current map shows where it is useful;
- repeat the antenna measurement after changing the common-mode boundary; and
- keep a final choke and station bonding arrangement appropriate to the complete shack installation.
A low SWR at the radio proves neither low feedline radiation nor a stable antenna pattern. Conversely, an exterior-current reading is not useful without a repeatable probe position, frequency, transmitter level and baseline.
Receive Is a Separate Engineering Job
The EchoTracer3 is planned on a wooden support at about 2 metres. The current product guidance presents 2–4 metres as a practical comparison range, not a maximum or universal optimum. That is exactly how OR7C/P will use it: start low enough for rapid deployment, move it away from obvious conductive clutter and noise sources, then compare wanted-signal SNR rather than S-meter level alone.
Whip choice and receiver-side Bias-T must cover the spectrum being monitored. The probe is receive only, and its 75-ohm signal path is a separate system from the transmit antennas. It is not “practically omnidirectional” under every installation: the whip, mounting reference, feedline, support and nearby conductors collectively determine what field reaches the receiver.
Transmit interlock is mandatory: the EchoTracer3 product package does not include an RX-disconnect-on-TX system. OR7C/P must positively isolate or protect the receive path whenever either transmitter is keyed. Antenna spacing alone is not a protection device, and receiver software is not a substitute for a tested hardware switching or protection sequence.
Three Antennas Can Still Behave Like One Coupled System
Separating jobs does not eliminate interaction. Transmit antennas couple to each other, to the receive probe, to feedlines, guying, frames, generators, network cables and the operating shelter. At a multi-band field station, the first practical limits may be receiver overload and inter-station interference rather than free-space antenna gain.
| Check | What to record | What the result can decide |
|---|---|---|
| Feedpoint and shack sweeps | Reference plane, frequency span, calibration, feedline state and geometry | Whether a change came from the antenna, feedline or measurement plane |
| Exterior-feedline current | Probe position, transmitter level, band and choke configuration | Where common-mode control is needed and whether it worked |
| Co-site transmit test | Every TX/RX band pair, power level, filter state and receiver symptoms | Required spacing, band-pass filtering, switching and power restrictions |
| Receive comparison | Same signal, same receiver state, A/B/B/A sequence or simultaneous channels | Whether the dedicated receive antenna improves copy under that noise and path |
| Support and safety inspection | Ballast, guys, clearances, access boundary, weather and cable strain | Whether the configuration is safe enough to energise |
Band-pass filters should be chosen for the actual transmit combinations and measured for insertion loss, rejection and power handling. Antennas should be spaced and oriented as far as the site permits, but the final protection plan must be based on coupled-power and overload tests at realistic transmit power.
The Field Day Plan Is a Controlled Experiment
The strength of this arrangement is not that one antenna is declared “best.” It is that every subsystem has a narrower job and can be changed without pretending the whole station stayed constant.
Document geometry, feedline routes, matching, choking, filters and receiver state before operating.
Test transmit-to-receive coupling, exterior current and overload across all intended band pairs.
Move height, choking, receive location or filtering one variable at a time and restore the baseline.
That approach preserves the original OR7C/P idea: do not ask one antenna to solve everything. It also makes the idea falsifiable. If the loop, low-band wire or receive probe does not deliver its assigned job at the site, the logs will show where the station needs a different geometry, filter, current boundary or operating compromise.
Bottom line: the DeltaRex, EFHW16080 and EchoTracer3 are the planned tools. Performance belongs to the installed OR7C/P system. Measure the current paths, protect the receive hardware, test every simultaneous-band combination and let the field results decide what remains.
Current product records checked
Mini-FAQ
- Why not use one antenna from 160 to 10 metres? Because the low-band radiator, upper-HF pattern, matching, receive noise and co-site protection impose different constraints. Separate systems make each job measurable.
- Does a 2-metre DeltaRex bottom height guarantee regional coverage? No. It is the first support geometry. Ground, terrain, loop shape, nearby conductors and feedline current determine the installed pattern.
- Will raising the EFHW16080 centre to 16 metres guarantee better 160-metre DX? No. It changes ground coupling and field addition, but the outcome requires an installed model or controlled field comparison.
- Where should the transmit chokes go? Use the maintained installation guidance as a starting point, then map exterior-shield current on every band and verify the result after each change.
- Is 2 metres the best EchoTracer3 height? Not universally. It is a practical starting point within the product page's 2–4-metre comparison range. Compare wanted-signal SNR and local noise with repeatable receiver settings.
- Can spacing protect the EchoTracer3 during transmit? Spacing reduces coupling but is not a protection guarantee. Use a tested RX-disconnect or protection/interlock system whenever a transmitter is keyed.