Tuesday, May 5, 2026

Just what is POTA anyway?

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Thursday, April 30, 2026

Hear and See ISS! plus weird signals

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Wednesday, April 29, 2026

random bandscan and a surprise live stream!

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Tuesday, April 28, 2026

My camera destroys the ISS Signals

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Thursday, April 23, 2026

Training Helps and you can only see this on Rumble

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How to Tune a Homemade 70cm Yagi Antenna (Optimized for 437.800 MHz)

Building your own 70 cm Yagi antenna is one of the most rewarding projects in amateur radio—but at UHF, precision matters. Small measurement errors can shift your antenna off frequency, so starting with accurate dimensions and tuning correctly makes all the difference.

In this guide, I’ll show you how to tune your antenna and give you a refined, field-tested 3-element design centered on 437.800 MHz—ideal for satellite work, weak signals, and directional simplex.

Why Precision Matters on 70cm

At 437.800 MHz:

Wavelength ≈ 68.5 cm (26.97 inches)
A 1–2 mm change can noticeably shift resonance
Feedline and mounting effects become more significant

This is not HF—you’re working in a range where millimeters matter.

📡 Optimized 3-Element Yagi Design (437.800 MHz)

These corrected dimensions will put you much closer to resonance right out of the gate.

Element Lengths

Reflector: 33.9 cm (13.35 in)
Driven Element (total length): 32.5 cm (12.80 in)
Director: 30.9 cm (12.17 in)

Element Spacing (Along the Boom)

Reflector → Driven: 13.7 cm (5.39 in)
Driven → Director: 10.3 cm (4.06 in)

Build Assumptions

Thin عناصر (≈ 1/8" or 3 mm rods)
Non-conductive boom (PVC recommended) or insulated mounting
Center-fed dipole driven element

Step 1: Set Up for Testing

Before tuning:

Mount the antenna in a clear, open space
Keep it away from metal objects
Use a short, good-quality coax feedline

For best results, use an analyzer like the NanoVNA to sweep the band and visualize resonance.

Step 2: Sweep for Resonance

Scan roughly 430–445 MHz and find:

The lowest SWR point

Interpretation:

Resonance below 437.800 MHz → antenna is too long
Resonance above 437.800 MHz → antenna is too short

Step 3: Adjust the Driven Element

This is your primary tuning control.

Too low in frequency → shorten slightly
Too high → lengthen (if possible)

Make very small changes:

1–2 mm at a time
Re-check after each adjustment

Step 4: Match It Properly

If you're using:

Gamma match
Hairpin match

Adjust for lowest SWR:

Target ~1.2:1 at 437.800 MHz

This step often makes the biggest performance difference.

Step 5: Verify Reflector and Director

These shape your antenna’s pattern and gain:

Reflector = longest
Director = shortest

If performance seems off:

Check spacing first
Then make very small length tweaks

Step 6: Add a Choke Balun

At UHF, feedline radiation can distort tuning.

Add a choke at the feedpoint:

Coil a few turns of coax
Or use ferrite beads

This stabilizes SWR and improves pattern consistency.

Step 7: Final Targets

A well-tuned antenna should achieve:

SWR ≤ 1.5:1 across your range
Ideally ~1.2:1 at 437.800 MHz

Real-World Builder Tips

Cut slightly long if you want room to trim
Always tune outdoors at operating height
Keep elements straight and aligned
Double-check spacing before drilling

Troubleshooting

If tuning isn’t working:

Re-measure all element lengths
Check feedpoint connections
Confirm choke balun is installed
Move antenna away from nearby metal

What Changed from Typical Designs?

Many online designs run slightly long, which shifts resonance lower (around 430–434 MHz).

This corrected version:

Centers resonance closer to 437.800 MHz
Reduces the amount of trimming required
Gets you on frequency faster

Final Thoughts

A properly tuned 70 cm Yagi can dramatically improve your signal—especially for satellite work and weak-signal contacts. With careful construction and a few small adjustments, you can turn a simple homebrew antenna into a high-performance directional tool.

ISS with a YAGI !

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Monday, April 20, 2026

Why I can't do this anymore

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Random SWL on Monday

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Friday, April 17, 2026

Comet C/2025 R3 PANSTARRS Pass by Earth

A bright comet is making its way through our solar system, and you might be able to go out to see it in the night sky.

Discovered this past September, Comet C/2025 R3 (PANSTARRS) has been steadily brightening throughout 2026, with predictions suggesting it will reach well within naked-eye visibility as it makes its closest passes to the Sun and Earth. To see it, head outside about an hour and a half before sunrise and face toward the east. It’s here that you’ll find Comet PANSTARRS as a faint, soft glow low on the horizon.

Try to spot it first with the naked eye, but you may need a pair of 10x50 binoculars to scan the sky until you come across it. If you own a telescope, switch to a low-powered eyepiece once you’ve found it to see the coma in more detail and possibly even a faint tail extending from it.

On the morning of April 19th, it will make its closest pass to the Sun and will appear near the star Alenib, somewhere around magnitude 2–3, putting it well within reach of naked-eye visibility. As it passes the Sun, PANSTARRS will get lower to the horizon each morning until it becomes too close to the rising Sun to safely view.

At this point, no one on Earth will be able to observe it for a few days because of how close it will be to the Sun. However, space-based telescopes, such as the Solar and Heliospheric Observatory, will be able to image and capture it during this time.

As it begins to move away from the Sun, it will become an impressive target for observers in the Southern Hemisphere. On April 26th, Comet PANSTARRS will make its closest pass to Earth, and from that date on, it will begin to slowly rise night after night in the western sky as a naked-eye object, possibly reaching between magnitude 1 and 0.

Head outside about 30 to 45 minutes after sunset and scan the western sky until you find it. As April transitions into May, the comet will climb higher in the western sky, offering increasingly better views. Predictions suggest it will remain visible to the naked eye throughout the first half of May.

As Comet PANSTARRS travels through the constellation Orion, it will make a close pass to the Orion Nebula around May 10th, creating excellent opportunities for astrophotography.

If this comet holds together and you’re able to observe or image it, share where you saw it from and what your experience was like in the comments below. If you enjoyed this content, consider liking and subscribing to stay updated on what you can see in the night sky.

Thank you all so much for your continued support, now get out there and look for this thing!