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Setting Up a Bug from Scratch
Just got your first bug? Here's a step-by-step walkthrough — from mechanical prep to sending your first dits.
🔩 Part 1: Pre-Setup & Physical Maintenance
Before making any functional adjustments, ensure the mechanical integrity of the key.
1
Tighten the base
Ensure all screws on the underside of the base are snug to maintain electrical continuity.
2
Clean bearing surfaces
The arbor (pivot post) must be clean. Use alcohol and a toothpick or cotton swab to remove oxidation from the trunion screw cups.
3
Polish the arbor tips
Use fine sandpaper (1000 grit) to polish the cone-shaped points of the arbor for smooth movement.
4
Adjust vertical play
Set the top trunion screw so there is just a tad of up-and-down play — enough to prevent binding, but not so much that it feels sloppy.
⚙️ Part 2: Initial Adjustments & Spacing
This stage establishes the geometry of the key's movement.
1
The damper
Back off the right trunion screw until the pendulum rests gently against the damper — without pushing it or vibrating.
2
Gap settings
Using a feeler gauge, set the gap between the left trunion screw and the lever to approximately .011 to .015 inches.
3
Dash contact
Set the dash contact gap to a similar distance (~.015 inches) to ensure consistent spacing between dots and dashes.
🎯 Part 3: Final Functional Setup
The final tuning involves setting the spring tension and the weight of the dots.
1
Spring tension
Start with springs at a medium (halfway) tension. They should be strong enough to return the lever quickly but light enough that the key doesn't walk across the table.
2
Weight placement
Place the sliding weights in the center of the pendulum for a balanced starting speed.
3
Dot contact timing
Move the dot contact in until the key produces roughly 12 to 15 solid dits before the vibration dies out or slurs into a continuous tone.
📺 Video Walkthroughs
These videos cover the full process from start to finish. Watch them in order:
Bug Setup Series — Thomas Waits, WA9CW
Foundational Reference — Jim, WB8SIW
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Getting scratchy dits? Here's what the operators recommend.
⚡ The "Descratcher" Debate
Capacitor-based "descratchers" are a common accessory sold to filter noise from bug contacts. Opinions vary on their effectiveness:
- The case for: DL6ZB's oscilloscope measurements show that a 330nF capacitor across the bug connections visibly reduces dit bounce at ~20 WPM. He recommends 220nF at the bug plus 100nF in the keyer jack for additional RF filtering.
- The case against: Some operators report minimal audible difference, or find that proper adjustment and contact cleaning solve the problem without added components.
- The radio factor: Your radio may already have built-in filtering on the key input. Icoms and Kenwoods typically do; many Yaesus don't. If your radio already filters, an external descratcher may be redundant.
"Same bug sounds lovely on an Icom or Kenwood and like hot trash on my Yaesu FT710." — AJ7CM
🔧 What Actually Helps
Before buying a descratcher, try these proven techniques:
1
Clean the contacts
Match your cleaning to the bug's condition: New/clean bug? Paper between the dit contacts is usually enough. Older bug? DeoxIT on the contacts. Antique with heavy oxidation? Fine polish compound. Wiggle the contacts while testing — if you get solid dits with the post rotated off-center, they're still grimy.
2
Adjust properly
Don't set up your bug like iambic paddles with tiny travel. Bugs want some slap — put velocity into those dits. A properly adjusted bug has more travel than you might expect.
3
The sponge trick
Cut a small piece of kitchen sponge and wedge it inside the gap of the dit spring. This reduces wobble and makes contact more consistent. Multiple operators (WO6W, AJ7CM) swear by this simple fix.
4
3D printed wedge
Some ops use a 3D printed wedge instead of sponge for a more permanent solution. Placing it closer to the contact point seems to work best. See K8CES's designs below.
🐢 Slowing Down Your Bug
Need to send slower? Moving the weight only goes so far. Arm extensions add mass to the pendulum, letting you reach slower speeds without sacrificing control.
🖨️ 3D Printed Improvements
K8CES has been experimenting with 3D printed accessories for Vibroplex bugs, including damper wedges and other improvements.
🎧 Diagnostic Tips
- Record yourself on WebSDR: What you hear locally (bug mechanics + sidetone) isn't what goes out on the air. Use a WebSDR to hear your actual transmitted signal.
- Try noise-canceling headphones: Helps you focus on sidetone rather than the mechanical clatter of the bug.
- Test on different radios: If possible, try your bug on another rig. Night-and-day differences between radios can reveal whether it's the bug or the radio's filtering.
📻 Radio Filtering Notes
Based on operator reports:
- Good filtering: Icom, Kenwood (generally)
- Less filtering: Yaesu FT710, some others
- Varies: Xiegu G90 (reported better than FT710)
Your mileage may vary — these are anecdotal reports from operators, not official specs.
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Maintenance & Restoration
Tips from elmers on keeping your bug clean, bright, and running smooth.
🧼 Ultrasonic Cleaning
An ultrasonic cleaner is a game-changer for bug maintenance. It removes dirt and brightens/polishes parts without manual abrasion — no polishing compound needed. Especially handy given all the small screws and parts in a bug.
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Recommended setup: A Vevor 6L ultrasonic cleaner works well. Mix up a gallon of ammoniated cleaning solution: ammonia, acetone, water, and Murphy's Oil Soap.
Alternatively, L&R makes off-the-shelf water-based solutions specifically for clock cleaning that also work great.
🦶 Replacement Feet
Original rubber feet often deteriorate or go missing over the decades. These replacement feet have been recommended by operators:
📋 Parts Lists
Official Vibroplex parts diagrams for current-production models. Useful for identifying replacement parts or understanding assembly.
Vibroplex Parts Diagrams (PDF)
✨ Nickel Plating / Refinishing
For bugs with worn or tarnished nickel plating, DIY nickel plating is an option. KD7DUG has used the following process to great effect:
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Watch the current! After ~10 minutes, you may see blackening on the metal. Turn the current down to 0.1 amps and voltage to 2.5V. The blackening rubs right off. Buff with a Dremel after the bath for a clean finish.
Tips compiled from the CW community.
Thanks to WA9CW, WB8SIW, AJ7CM, KD7DUG, K8CES, WO6W, KG5VNQ, DL6ZB, and others.
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