The Electronmans Hub

If you’re looking at the RadioDity HF-008, you probably already know what it is: a compact, multiband, loaded vertical antenna aimed at mobile and portable HF operation. This article skips the unboxing fluff and focuses on how it actually works, how to tune it efficiently, and why I modified mine for fast band changes in the field.

What Comes in the Kit

The HF-008 kit is straightforward:

• Main antenna base with SO-239 connector
• Primary loading coil with numbered tap points
• Extension section
• Two tuning whips (one short, one long)
• Small Allen wrench (more on this later)

No surprises here — everything you need to assemble and tune the antenna is included.

How the HF-008 Actually Works

At its core, the HF-008 is a multi-tap loaded vertical. The coil is wound continuously from bottom to top, with numbered tap points along the way.

By moving a jumper between tap points, you are effectively shortening or lengthening the electrical length of the antenna — exactly the same concept as adjusting the length of a dipole.

• No jumper installed: full coil in use (80 meters)
• Lower taps: longer effective length (40m, 30m)
• Higher taps: shorter effective length (20m, 15m, 10m, 6m)

Fine tuning is handled by sliding the whip in or out of the extension and locking it in place with a set screw.

Why I Modified Mine (Yes, I Cut a Brand-New Antenna)

Let’s address the obvious question: why cut a brand-new antenna?

After reviewing the manufacturer’s tuning chart and verifying it with a VNA, something stood out immediately:

• The total whip length variation across all bands is only about 11 inches
• The “long” whip bottoms out at ~32 inches when fully seated
• That length is only required for one configuration
• The short whip can already cover the entire tuning range

In other words, the long whip is functionally redundant — except that it prevents presetting two different band lengths.

Since this antenna is ideal for POTA-style operation, where I primarily work 20m and 40m, I wanted a faster solution:

• One whip permanently tuned for 20 meters
• One whip permanently tuned for 40 meters
• Quick band changes without re-measuring or sliding whips

By trimming the long whip by approximately six inches, I was able to preset two whips for two bands — swap the whip, move the jumper, and be on the air in under a minute.

This is a personal modification based on my operating style. I am not telling you to cut yours — just explaining why it made sense for me.

VNA Results (What the Measurements Show)

Using a VNA, I measured each configuration directly at the antenna. The results were exactly what you’d want to see from a portable HF antenna:

• 20m whip: clean resonance centered in the band
• 40m whip: wide usable bandwidth, much broader than expected
• 10/11m: extremely broad coverage by simply moving the jumper

In fact, the antenna shows excellent broadband behavior from roughly 26–29 MHz, making it a very easy 10m (and even 11m) solution.

Images of the VNA plots can be inserted here.

Mounting and Ground Considerations

The HF-008 uses an SO-239 base, which gives you flexibility in mounting. I used a heavy-duty triple-magnet mount, but this antenna is surprisingly stable even when placed directly on the ground.

From initial testing, ground coupling appears to be very forgiving:

• Ground placement works well for portable operation
• Vehicle mounting provides a solid RF ground
• Metal objects (grills, benches, rails) can work in a pinch

One Small but Important Tip: The Allen Wrench

The included Allen wrench technically works — but barely. It fits loosely and will almost certainly strip the set screws over time.

A properly fitting 5/64″ Allen key seats much better than the supplied tool and is worth using from day one.

Final Thoughts

The RadioDity HF-008 isn’t magic — it’s physics — but it’s a very well-executed portable HF antenna.

• Solid construction
• Predictable tuning
• Excellent flexibility for portable and mobile HF
• Especially well-suited for POTA-style operation

With a little planning — and optionally a simple modification — it becomes a fast, efficient, multiband antenna that’s easy to live with in the field.

73s — Electron Man