[Elecraft] securing toroids in K2, why not?

[Don Wilhelm]

  Ron,

I suggest that you indeed do that.  Actually on RFC14 it will likely 
make little difference because the exact inductance is not critical, but 
once the RTV hardens, you will have a bear of a time getting it off 
should it ever need replacement.  Do not use any fixatives on any more 
of the K2 toroids.  Many compounds will alter the inductance, and it is 
just not necessary.  To emphasize that point, I often refer to the K2 
that I built for an OTR truck driver.  That K2 lived for years in the 
cab of his 18 wheeler, and never suffered any toroid damage - the 
toroids were adequately supported by their leads.

More specifics, T5 (and sometimes, but not often, the inductors in the 
LPF) may need "tweaking" by adjusting the turns spacing.  The use of any 
fixatives will prevent that, and require you to purchase new cores and 
rewind the toroids.

Build the K2 as specified in the manual, and you will have no problems - 
if you add or subtract anything, it may not work correctly.

73,
Don W3FPR

On 7/2/2011 9:02 PM, R Thompson wrote:
>     I just installed the first toroid, RFC14, in my K2 kit.  After
> winding it, I sprayed it with conformal coating, and just before
> installing it I put a small dab of RTV3145 (non-corrosive) silicone seal
> on the end next to the PC board and then soldered it in place.
>
>     So.... I turn the page in the manual and the very next thing in bold
> is "Do not use adhesives or fixatives of any king to secure toroids to
> the PC board.
>
>     Would this also apply to conformal coating?  Should I remove RFC14
> and take the RTV off it?
>
>