[Elecraft] K3, KX-1 Inductors

[Don Wilhelm]

Scott,

Read the warning on page 9 of the K3 assembly manual.
It specifically states:
"Also, do not attempt to fix the turns or coils in place with adhesives 
or other materials.
Those toroids needing support have been fixed at the factory. Adding 
material to the other
toroids will alter their inductance, again degrading circuit performance."

In other words, don't do that.  The K2 and K1 carry the same warning as 
the KX1.  I have encountered some of the Elecraft legacy gear in for 
repair that had the toroids fixed to the board with some kind of 
adhesive, it make them a mess to work with.
There have been several K2s that I know about which have been mounted in 
a high vibration environment such as the cab of an OTR truck, and the 
toroid leads have not failed.  The toroids were not fixed in place with 
any adhesive in at least one case - I know that because I built it for 
the customer.

If you do use a fixative, be aware that in the case of repair, toroids 
fastened like that are very difficult to remove and the board may be 
damaged in the process.  I have been there, done that.

73,
Don W3FPR


On 3/26/2016 12:24 AM, Scott Ellington wrote:
> My K3 hasn't traveled much, but if it did, I'd be very concerned about 
> all the inductors supported only by their leads.  It seems certain 
> that vibration would result in leads breaking.  However, there's a 
> note in the KX-1 assembly manual specifically warning against 
> fastening the inductors to the board with adhesive. (That's exactly 
> what I was planning to do.)  Why not?  I doubt the reason is 
> electrical, unless it's stray capacitance.  The only other reason I 
> can think of is that those handling power might get hot enough to melt 
> an adhesive.  If that's the case, I'd really like to find another way 
> to secure them.  Any suggestions?
>
> Or maybe someone can assure me that with all those K3 getting shipped 
> all over the planet for DX-peditions, etc., none of those wires ever 
> break.  Ever.  (I'd still take along some magnet wire.)