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Author Topic: Key Bounce Problem  (Read 508 times)

K3ZD

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Key Bounce Problem
« on: March 31, 2022, 06:07:36 AM »

I recently got two bugs, since I always wanted to try to learn using one.  One is a Vibroplex Original and the other is a KN4YB.  I don't have contact bounce or scratch problems with a FT-450 but its really annoying on my FTDX10.  I don't like building stuff anymore.  Don't have the steady hand or good eyes I used to have.  Is there any commercially made product I could use as a debouncer?  Before you say - its your technique or key adjustment, I repeat I don't have a problem with the FT-450.
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K1KP

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Re: Key Bounce Problem
« Reply #1 on: March 31, 2022, 06:13:15 AM »

The 450 may have an internal debounce circuit that helps it to work properly. Most modern rigs do the CW keying in software, and the implementation in the 450 may be better at filtering the keying lines.

You may be able to solve the problem simply with a small capacitor across each set of contacts. Start with .01uF and work your way up.
-Tony, K1KP
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G4LNA

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Re: Key Bounce Problem
« Reply #2 on: March 31, 2022, 06:41:32 AM »

Just to give you a head start on the capacitor that Tony mentions. I solved my FTDX10 problem with a 0.33µF across the key contacts, hopefully that will save you fiddling around trying to find the right cap that works, that was after trying various caps before ending up with the one mentioned.

73 Paul.
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VE3HIX

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Dental floss
« Reply #3 on: March 31, 2022, 07:42:06 AM »

In addition to the capacitor, you could try about four turns of dental floss wrapped and tied around the dit spring. This works for all of my bugs when connected to modern Kenwood rigs, but it raises the minimum speed of the dits by about one WPM.

For a commercial product, I noticed that KN4YB has a mechanical bounce dampener that attaches to the arm and is adjusted against the dit spring. I don't know whether he sells them separately.

Cheers,
Bob VE3HIX
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KH6AQ

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Re: Key Bounce Problem
« Reply #4 on: March 31, 2022, 08:00:07 AM »

I designed an active bug debouncer circuit in 1992 and a version of it is sold in kit form by WB9KZY as the Bug Descratcher Kit III.

I don't like the idea of placing a capacitor across the contacts because the bug contacts are then subjected to very high current capacitor discharges and this could erode them.

http://wb9kzy.com/bugde3.htm
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W9AC

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Re: Key Bounce Problem
« Reply #5 on: March 31, 2022, 08:46:26 AM »

I designed an active bug debouncer circuit in 1992 and a version of it is sold in kit form by WB9KZY as the Bug Descratcher Kit III.

For folks who like to build things, another option is my "S-QSK Mini" device, shown at the top of my QRZ page.  The total cost is slightly more than the WB9KZY kit, mostly due to shipping charges from two different vendors.  The PC board Gerber files are available on the same QRZ page -- or order the board directly from OshPark.  I've nothing to sell.  Files and instructions are all free.  No need to hunt down parts; parts can be ordered with a "one-click" link to Mouser. 

A few benefits:

1) Precise, user adjustable debounce time in 1 ms. increments with a simple one-line code change;
2) RCA phono input and output connectors.  No wires soldered to the S-QSK Mini board.  Just grab RCA cables;
3) No soldered wiring for power.  S-QSK Mini is powered exclusively from any USB jack including a close-by PC, iPhone wall cube, or any of the hundreds of +12v to USB powering devices;
4) Full optical input and output isolation to mitigate RFI issues;
5) Output device is an Ixys PLA140, fully balanced above ground potential and will key AC or DC loads. Standard positive or high voltage grid-block keying -- it doesn't matter.

Because of the debounce time flexibility, it does require flashing the code to the microcontroller using free Arduino IDE software.  S-QSK Mini construction time should be under 15 minutes, even for those with minimal kit building skill.

Paul, W9AC
« Last Edit: March 31, 2022, 08:54:35 AM by W9AC »
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W6MK

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Re: Key Bounce Problem
« Reply #6 on: March 31, 2022, 10:54:20 AM »

http://wb9kzy.com/bugde3.htm

Some otherwise well-designed transceivers are very sensitive to contact bounce when using mechanical keys of any sort, not just bugs. The assumption is that most if not all hams will be using paddles and the built-in keyer.

I use the debouncer mentioned above. Works great. Simple assembly of the kit.
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VE3HIX

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Re: Key Bounce Problem
« Reply #7 on: March 31, 2022, 05:30:56 PM »


I don't like the idea of placing a capacitor across the contacts because the bug contacts are then subjected to very high current capacitor discharges and this could erode them.

http://wb9kzy.com/bugde3.htm

I have noticed sparks at the contacts when using a capacitor in a vacuum tube grid keying circuit, but not in a solid state keying circuit. The contacts stay clean.

Cheers,
Bob VE3HIX
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G4LNA

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Re: Key Bounce Problem
« Reply #8 on: April 01, 2022, 07:16:24 AM »


I don't like the idea of placing a capacitor across the contacts because the bug contacts are then subjected to very high current capacitor discharges and this could erode them.

http://wb9kzy.com/bugde3.htm



I have noticed sparks at the contacts when using a capacitor in a vacuum tube grid keying circuit, but not in a solid state keying circuit. The contacts stay clean.

Cheers,
Bob VE3HIX

Exactly! With a 0.33µF capacitor with about 3 volts gives about 1.6 microjoules.
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K3ZD

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Re: Key Bounce Problem AND another question now added.
« Reply #9 on: April 17, 2022, 02:14:12 PM »

Here's my follow up.  I ordered the Bug Debouncer kit by WB9KZY and it works really well with my Vibroplex bug.  But my KN4YB bug and my Yaeseu FTDX10 just don't get along, even through the debouncer.  No matter what I do the dots have a chirp.  Its his model with the straight blade dot contact.
 KN4YB says in his Youtube setup videos the straight blade bugs don't have a chatter problem but I am not finding that to be the case, at least with the FTDX10. 

Another question.  Now that I'm used to the bug I find I can't go back to automatic electronic keying with a paddle.  So if any of you bug users go portable like POTA, do you bring your nice bug with you or do you use something else?  For portable I use a Yaesu FT-450 but it does not have an option for semi-automatic electronic keying. 
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KH6AQ

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Re: Key Bounce Problem
« Reply #10 on: April 17, 2022, 07:34:29 PM »

While I occasionally use a bug I have not used one when portable. If I were to do so I'd take my Hi-mound coffin bug. I have seen paddle/bug users transition between the two devices two different ways. Long ago Edith Smith, K6PRN, told me she worked a bug with one hand and would work a paddle with the other hand. Me, I switch automatically between the two with no problem.
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NI0C

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Re: Key Bounce Problem
« Reply #11 on: April 18, 2022, 08:19:59 AM »

Quote
For a commercial product, I noticed that KN4YB has a mechanical bounce dampener that attaches to the arm and is adjusted against the dit spring. I don't know whether he sells them separately.
W0EB also sells mechanical dot stabilizers that can be helpful. Accomplishes the same thing as the dental floss trick mentioned above. 
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