Late June: Ferrites, Feedlines, and the Parts Theory Leaves Out
By late June, most stations have settled into their summer shape. The antennas are up, the ferrites are clipped on, the meters are being watched, and the same old simplifications are back: SWR is being treated like truth, feedlines are being treated like abstractions, and somebody is still hoping one antenna will do everything well.
That makes this a good moment to revisit the parts of HF that are easy to flatten into neat stories: what meters are really showing, where SWR should be measured, what ferrites actually do, why theory and practice keep parting ways, and why receive performance still refuses to be an afterthought.
So this issue is about exactly that: the difference between a useful model and the whole RF reality, and why better stations start when we stop mistaking one for the other.
The Transmission-Line Model Is Not the Whole EM Reality
A necessary correction for anyone who starts treating a useful model as if it were the full electromagnetic behavior of the system.
🔗 https://shop.rf.guru/pages/the-transmission-line-model-is-not-the-whole-em-reality
Why Not Use a Galvanically Isolated Transformer for HF?
A good example of how a clean-looking idea can run into trouble once actual HF behavior and return paths enter the conversation.
🔗 https://shop.rf.guru/pages/why-not-use-a-galvanically-isolated-transformer-for-hf
Ferrite Sleeves vs FT240 Cores: Why There Is No Simple 1:1 Comparison
Same ferrite category, very different mechanical and electrical realities.
This one explains why “equivalent” is often doing far too much work.
🔗 https://shop.rf.guru/pages/ferrite-sleeves-vs-ft240-cores-why-there-is-no-simple-1-1-comparison
Clip-On Ferrites and RF Transmission Lines: From HF to UHF
A practical look at where clip-ons help, where they do not, and why frequency range changes the story dramatically.
🔗 https://shop.rf.guru/pages/clip-on-ferrites-and-rf-transmission-lines-from-hf-to-uhf
A Ferrite Around Coax Measures Common-Mode Current, Not Shield Leakage
One more measurement myth cleaned up properly: the ferrite tells you something useful, just not the thing people keep naming it.
🔗 https://shop.rf.guru/pages/a-ferrite-around-coax-measures-common-mode-current-not-shield-leakage
Where Should SWR Be Measured?
A simple question that becomes much less simple once the feedline, tuner, and actual antenna current paths are all allowed into the answer.
🔗 https://shop.rf.guru/pages/where-should-swr-be-measured
What Your FWD/REV SWR Power Meter Is Actually Showing
A useful reset for anyone who has been reading the meter with more confidence than context.
🔗 https://shop.rf.guru/pages/what-your-fwd-rev-swr-power-meter-is-actually-showing
Reflected Power, SWR, Tuners, and Finals
A practical cleanup of one of amateur radio’s most persistent anxiety loops:
what really gets stressed, what the tuner changes, and what the finals actually “see.”
🔗 https://shop.rf.guru/pages/reflected-power-swr-tuners-and-finals
Ground Tuning Units and Artificial Grounds in Ham Radio
Another case where a familiar product category sounds clearer than the physics behind it really is.
🔗 https://shop.rf.guru/pages/ground-tuning-units-and-artificial-grounds-in-ham-radio
EFHW Efficiency: Any Antenna Works. That Was Never the Issue.
A timely reminder that “it makes contacts” is not a serious efficiency argument, even if it is often used like one.
🔗 https://shop.rf.guru/pages/efhw-efficiency-any-antenna-works-that-was-never-the-issue
The Very Efficient Antenna That Radiates to Nowhere
A good title, and an even better correction: efficiency alone does not guarantee useful radiation in useful directions.
🔗 https://shop.rf.guru/pages/the-very-efficient-antenna-that-radiates-to-nowhere
DX Is Not Always Low Angle
A welcome reminder that propagation mythology often outlives the conditions that created it.
🔗 https://shop.rf.guru/pages/dx-is-not-always-low-angle
Diversity Receive on HF: Why One Antenna Is Often Not Enough
Receive performance is still a system problem, and this one shows why a second view of the same band can matter more than people expect.
🔗 https://shop.rf.guru/pages/diversity-receive-on-hf-why-one-antenna-is-often-not-enough
Theory and Practice Are Different in HF
A title that almost sounds too obvious — until you remember how many arguments collapse the moment real installations enter the picture.
🔗 https://shop.rf.guru/pages/theory-and-practice-are-different-in-hf
Who Really Invented Morse Code: Samuel Morse or Alfred Vail?
A small historical detour, and a useful reminder that even foundational radio stories are often tidier in retelling than they were in reality.
🔗 https://shop.rf.guru/pages/who-really-invented-morse-code-samuel-morse-or-alfred-vail
Prefer to watch the measurements, hear the reasoning, and skip the late-June crop of oversimplified RF certainty?
Mark covers many of the same themes with calm explanations, practical demonstrations, and a very welcome resistance to magical thinking.
🔗 Watch the featured videos from our collaboration
If this issue leaves you slightly less impressed by neat meter readings, slightly more cautious around oversimplified ferrite comparisons, and slightly more interested in what the full station is actually doing — good.
That is a very healthy way to end June.
73,
Joeri – ON6URE
Founder – RF.Guru
https://rf.guru/