KX3 encoder issue

While operating on DM/BW-852 I encountered an issue with the Keyer/Mic- encoder of my KX3. For about a minute it wasn’t possible to change the keyer speed. Luckily the speed was set to a reasonable value (20 wpm). Then, maybe by touching the knob differently, it worked again.
A couple days ago, when preparing the activation, I had the same issue while trying to reduce the KX3’s output power. I pushed the button (the display showed 10 W) and turned the knob. The reading went down to 9.8 and stayed there regardless of any further turning. I switched to „keyer speed“ by pushing the knob (which actually worked) and tried to change the keyer speed to no avail. Then I switched back to output power and turned the knob again: the encoder did not work. Even after switching the KX3 off an on, it remained in this state.

Next I opened the KX3, took out the CP- board and did some resistance measurements at the back side of [Z4]. Now the encoder seemed to be working again. After assembling the KX3 everything worked smoothly.

It looks like the encoder has an issue. But before I replace it (or even all four of them) I asked the experts at ELECRAFT for a confirmation. The reply arrived within a few hors (!)

„Hi Roman,
Thanks for the contact.  To your questions on the KX3 encoders, we have received reports of some encoders losing some of the damping fluid that is embedded into the shaft and sleeve.  These are sealed but can leak.  When this happens, some of the fluid will get into the optical encoders and cause the symptoms you are seeing.
Generally, we recommend all 4 be replaced at the same time to save having to do them individually.  We do this with the K3 and K3S encoders in much the same way.
The KX3 encoder is Elecraft part #E640018 at $2.08 each.“

The encoders are already ordered and will be replaced as time permits. Thanks ELECRAFT for the fast support!

Edit:

In the meantime, I took the defective device apart. To my surprise it was a contacting encoder rather than an optical one.

encoder_1
There is some fluid visible in the picture above. If this gets on the contacts it could cause trouble.

encoder_2

Most likely the encoder is from Bourns. The data sheet can be found under this Link.

 

10 Gedanken zu “KX3 encoder issue

  1. Ged Wilkinson 3. Juni 2019 / 14:34

    Can you confirm the price that you paid for the KX3 encoders from Elecraft? The email in your blog quotes Elecraft saying they are $2.08 each. Waters & Stanton, Elecraft’s main dealer in the UK, has just quoted me £35.00! I am hoping that this figure is a mistake otherwise it would appear somebody is excessively profiteering on what appears to be a inherent design issue/faulty part!

    • dl3tu 3. Juni 2019 / 16:48

      Hi, the price was indeed USD 2,08 per piece.
      Shipping to DL was about twice as expensive as the four encoders.

    • Ged Wilkinson 7. Dezember 2019 / 16:33

      When I asked Waters and Stanton to check that they had quoted me for the correct part and that the price quoted was correct they initially insisted that this was for the correct part and that the price was correct. I pointed out that Elecraft were actually selling that part for $2.20 and recommended changing all four encoders at the same time so purchasing 4 encoders from Elecraft US would cost me a total of $8.80 plus $20 shipping a total of $28.80. Purchasing the 4 encoders from them would cost me £140 which, even taking into account import duties and VAT, appeared to be an outrageously large mark up. They eventually responded that they had re-checked the prices and their original engineer „was way off the mark“ and that the actual cost was £9.95 each (still a 500% mark up!).

      In the end I purchased 5 encoders from Mouser UK for £1.46 each.

      I only replaced the one faulty encoder as I found removing the encoder was quite difficult due to the amount of solder around the main encoder casing pins. Combined use of de-soldering braid and a de-soldering sucker tool eventually did the trick. But care is needed to ensure you use just the right temperature to melt and remove the solder quickly to minimise the risk of damaging the PCB. Having replaced the one faulty encoder I erred on the side of caution and followed the old edict ‚if it isn’t broken don’t fix it!‘

  2. chaplinhugo 7. Dezember 2019 / 04:46

    Hello,
    Do you have Bourn’s exact part number?
    If I can have the room locally or at a lower cost I’d better.

    Thanks/Merci!

  3. Ged Wilkinson 7. Dezember 2019 / 15:55

    Elecraft Part E640018 Encoder, 80 Counts,w/PB Switch is manufactured by Bourns Inc.

    Bourns part number is PEC11R-4015F-S0018

    It can be purchased from:

    Digi-Key here https://www.digikey.com/product-detail/en/bourns-inc/PEC11R-4015F-S0018/PEC11R-4015F-S0018-ND/4699185

    Mouser UK here https://www.mouser.co.uk/ProductDetail/bourns/pec11r-4015f-s0018/?qs=Zq5ylnUbLm7fgcChbBK5PA==&countrycode=GB&currencycode=GBP

    Mouser EU here https://eu.mouser.com/ProductDetail/bourns/pec11r-4015f-s0018/?qs=Zq5ylnUbLm7fgcChbBK5PA==&countrycode=DE&currencycode=EU

    The Bourns Data Sheet can be downloaded here: https://eu.mouser.com/datasheet/2/54/PEC11R-777457.pdf

    Best Regards,

    Ged, G4XQL

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