Important: updated assembly guide (v1.1) for the aluminum enclosure

There is an updated assembly guide (version 1.1) for those of you who have purchased the new aluminum enclosure. Corrections to the parts list, clearer photos and an important note about removing one of the two pieces of sticky tape attached to the fan. Special thanks to Dave, PJ4VHF, from Bonaire for discovering the issue.


KA7U

Comments

  • Page layout is better too. Thanks!
  • Just put mine together, the instructions were excellent.
  • good to know I wasn't the only one tripped up by the twin tapes 8-X
  • One issue I have noticed, the fan is vibrating, making an annoying sound. Anyone else have this problem? I Fonzi tap every now and then fixes it, for a while.
  • I have four operating Kiwis scattered about, and at least two of them have somewhat "buzzy" fans - but they are still operating OK. I think that this is more of a mechanical vibration of the fan's rotor than a noisy bearing/bushing, but I have on my list to get more of them on-hand (of a different brand) - just in case this vibration turns out to cause excess wear.

    I have on my "short list" of things to do to re-lubricate one of the noisiest of the lot (which happens to be on my ham shack) them with PTFE oil (which lasts much longer than the terrible stuff typically used by the manufacturer) to see if this helps: If it does, I'll have to reconsider what to do about the fans - and when - as that would not bode well for longevity.

    Clint
  • Mine's always noisy on start-up, has been for a year(?)
  • edited March 2019
    I have a bit of follow-up related to the KiwiSDR case fan. It would appear that at least some the noisiness is likely related to insufficient/poor lubrication after all.

    Having powered down my Kiwi for a week or so due to other work in my shack, I powered it up again a while back, hearing it "shudder" as it tried to spin up. In the past, I've noted that this can often happen with a cold fan with an "Oilite" (sintered bronze) bushing that is dry. These sorts of "bearings" are very common in inexpensive fans, but they have a few weaknesses, including:

    - The oil used in cheap Chinese fans seems to "dry out" rather quickly. It seems that the volatiles slowly evaporate, leaving behind heavier fractions. (I've noticed that it often smells slightly of naptha - not usually a sign of quality...)

    - Oilite, by its nature, often tends to be "dry" when cold: Warming up, the embedded lubricant will often come to the surface, but this may take a while.

    - If it goes on too long, the bearing surfaces can become worn and/or "coked" (e.g. surface lubricant may be cooked to a sludge/solid from friction) and reduce the ability of the embedded lubricant within the oilite to surface - if there's even any left.

    * * *

    Over the past 15 years, in non-critical applications (and because I may not have had a new fan of the same size - or because I was cheap...) I've actually "fixed" sleeve-bearing fans just to see what would happen over time. Sometimes this "fix" was simply re-lubricating it, but other times it required disassembly and cleaning with denatured alcohol to remove gum from the "dried" oil, reassembling and re-lubricating. In particularly tough cases, I would heat up the oilite bushing with a soldering iron before applying the new lubricant to help work it into the pores.

    Unless the sleeve bearing or spindle shaft was physically damaged (due to galling, perhaps) the "rebuilt" fan has lasted far longer than the time before the fan had failed - and almost none of these have failed since. Some of these re-lubed sleeve fans have out-lasted ball-bearing fans, which often have lubricant that is of no better quality than is found in the sleeve bearings and offers little benefit in longer life: Typically, when this happens to ball-bearing fans, they cannot be fixed because the balls/races have been damaged/spalled from running dry.

    * * *

    Such seems to be the case of many of these very inexpensive fans, including the fan that comes with the Kiwi case: Insufficient/poor quality oil that evaporates quickly (within a year or so) resulting in noisy operation.

    Carefully peeling the sticker back, I put a few small drops of a PTFE (Teflon) based synthetic lubricant - the same that I have used to "fix" fans in the past (as well as "un-gall" potentiometer shafts on an audio amplifier at my work about 20 years ago - none of which have "re-galled" since). This stuff is sold in the U.S. as "Super Lube" (made by Synco) which is a liquid in a bottle or a small pen-sized dropper - readily available on Amazon.

    After working the new lubricant into the bushing (sliding it back and forth to distribute it) I cleaned the plastic housing with a cotton swab and alcohol and covered it with a round piece of plastic tape (the reason for cleaning the plastic) to keep dust out of it. (Note that "Household oil" or "3-in-1 oil" should not even be considered for this purpose - and is probably similar to what was originally used. Don't even think of something like WD-40!)

    Since it was re-done, the fan's noise has been only a slight whine of the fan's BLDC driver and air movement - it wasn't this quiet when it was new.

    I have three more Kiwis at a remote site, all of which are getting noisier every time that I go there, and they will all get the same treatment on the next site visit and will be observed in the long term.

    Clint
    KA7OEI
    n6gn
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