Remote vs. Shack Tuner for Greyline Antennas: Which Setup Is Right?
Do I Really Need a Tuner at the Base of My Greyline Flagpole or HF Vertical Antenna?
The VDA Is Not a Monoband Antenna
The Greyline VDA (Vertical Dipole Antenna) is a broadband HF vertical designed to cover 160-6M. No single physical antenna element resonates on all those bands simultaneously. The VDA feedpoint presents a range of impedances across the HF spectrum — some bands close to 50Ω, others significantly off. An ATU (antenna tuning unit) matches that impedance to your radio and coax across all bands.
The question is not whether to use a tuner — it’s where to put it.
Remote ATU at the Base of the Antenna
A remote ATU mounted at the antenna base — the SGC-237, LDG RT-100, or similar — matches impedance right at the feedpoint. From the tuner to the shack, the coax sees a matched 50Ω load on every band. This is the cleaner RF solution.
Any coax grade works — even RG-8X on longer runs
No high-SWR voltage on long coax runs — cleaner signal
Simplifies shack: no ATU taking up desk space
Best choice for: runs over 75 feet, older coax, operators who want maximum low-band efficiency
Higher upfront cost ($150-$2500 depending on unit)
Some units power-limited — verify FT8 duty cycle rating before buying
Note: For high-power digital, use a desktop ATU — confirm FT8 duty cycle rating with ATU manufacturer before purchase.
Shack Tuner at the Radio End
A shack-side ATU — internal to your radio, an outboard auto-tuner, or a manual tuner — matches impedance at the radio end. The coax between antenna and shack runs at the raw antenna impedance on each band, which can be high on some bands and frequencies.
This is exactly how Bill (Florida HOA, 20’ flagpole, IC-7610 + AL-80B) runs his station — 40’ of LMR-400 from antenna to shack, Heathkit SA-2060 on the desk. Result: DXCC on 40M, 17M, 80M into Hawaii and India, 1,200+ DXCC Challenge additions. The shack tuner works.
No outdoor hardware, no DC control cable
Full power handling — rated for your amplifier
Easily swapped or upgraded
Best choice for: short runs under 50 feet, operators with existing desktop tuners, FT8 or amplifier use
Loss increases significantly with run length and frequency
Coax grade matters more — LMR-400 minimum, LMR-600 better
Rule: if your run exceeds 75 feet, upgrade coax for best results. RG-8X at 100 feet on 40M loses enough signal to matter. Bigger diameter coax has science backing on this topic.
The Coax You Choose Changes Everything
With a shack tuner, the coax carries unmatched impedance on many bands. Loss in that run matters. Here’s how coax grades compare at 100 feet on 14 MHz (20M), approximate:
RG-8X: ~1.5 dB — acceptable for short runs only
LMR-400: ~0.7 dB — minimum recommended / most of us use this
LMR-600: ~0.4 dB — better, worth the cost on long runs. A serious recommendation.
Hardline: ~0.2 dB — best, use where practical
Note: Loss scales with SWR. At 3:1 SWR on RG-8X at 100 feet, actual loss can exceed 4 dB. That’s nearly two S-units. Go up in coax grade before going down in tuner position.
For a full feedline selection guide including ladder line and open-wire options, see the Feedline Physics page → Signal Lab.
The Issue Both Tuner Options Share
Regardless of where you put the tuner, the feedline connecting a vertical antenna to your shack can carry common mode current — RF flowing on the outside of the coax shield rather than inside it. This causes RF in the shack, noisy receive, and in extreme cases can affect your radio’s performance or create RF feedback in audio circuits.
The fix is a common mode choke (line isolator or balun) at or near the antenna feedpoint. A string of snap-on ferrites on the coax, properly selected for the frequency range, also works. Bill’s station uses a 1:1 coax common mode choke plus six snap-on ferrites at the house entrance — result: no RF in the shack on any band.
Recommended: Install a common mode choke at the antenna feedpoint (or within a few feet of it) regardless of your tuner choice. This is the single most effective step you can take for clean receive and no shack RF. The Greyline Maxi Line Isolator and Mini Line Isolator are purpose-built for this application.
Which Setup Is Right for You?
Coax run 50-100 feet? → Shack tuner with LMR-400 minimum. LMR-600 preferred.
Coax run over 100 feet? → Remote ATU preferred, or LMR-600 / hardline to shack tuner.
Running FT8 at 100W+? → Verify tuner duty cycle rating. Many remote ATUs are not rated for sustained digital mode operation.
Running an amplifier? → Shack tuner is simpler. Verify it handles your power level.
Want the cleanest station possible? → Remote ATU + common mode choke + LMR-400 to shack.
Either choice gets you on 160-6M. Both have been proven in the field. Choose based on your run length and power habits.
Go Deeper in the Signal Lab
-
Feedline Physics: Coax, Loss & Line Selection →
Live loss calculator, coax comparison table, decision tree, and noise audit walkthrough. -
RF Mastery: The Physics of Balance →
Common mode current, isolation vs. balance, and why the choke position matters. -
Remote vs. Shack Tuner: Full Technical Discussion →
Extended technical breakdown of both configurations with real-world loss calculations.
Have a specific question about your run length, coax grade, or tuner choice? Call us — 435-200-4902. We enjoy talking radio.
73 Greyline Performance — Ham Radio is fun again!
