[Elecraft] securing toroids in K2, why not?

[R Thompson]

Thanks Don,

     good point on the LCR meter, it measures values at 1KHz.  The
remaining coils are being installed as per the manual.

     I service avionics for living, the better gear has conformal coated
boards.  The coating is very thin, applied as an aerosol, and hasn't
been a problem for repairs, a soldering iron will melt through it no
problem.  Older coatings, which were applied very thick, were a
headache.  Its hard not to want to use it, I've had my gear end up in
puddle at Field Day after a gust of wind blew over the tent, tables, and
all.

     First things first, I'll finish it as per the manual.

     The help here has been wonderful, and fast!  Thanks everyone, and
enjoy your long weekend!

               Ron VE8RT

     

On Sat, 2011-07-02 at 22:14 -0400, Don Wilhelm wrote:
> Ron,
> 
> Forget the LCR meter with the K2 kit - other than to evaluate the 
> effects of various "fixatives" for toroids.
> Wind the toroids with the number of turns specified and all will be OK.
> 
> As far as conformal coating, again, it makes repair or rework a "pain" - 
> but if you insist ...
> What I can say is that I have worked on many K2s (over 600 to date), and 
> some have been subjected to extreme environmental conditions (salt 
> spray, high humidity, etc.), and on all of those, even though the 
> exterior of the K2 shows signs of corrosion from that environment, all 
> those I have seen look "pristine" on the surfaces of the boards.  Based 
> on that, I would discourage using any conformal coating, it is just not 
> necessary unless you intend to dip your boards in salt water.
> 
> I have no idea what problems may occur if you would use a conformal 
> coating, other than that the coating must be "worked through" if any 
> repairs or upgrades are needed in the future.
> 
> When measuring with an LCR meter, be certain it is working at the 
> frequency that the toroid will actually be used.  Many LCR meters work 
> at a low fixed frequency, and the results obtained from those meters can 
> be misleading when the toroid is used at the frequency that it was 
> designed for.
> 
> 73,
> Don W3FPR
> 
> On 7/2/2011 9:48 PM, Ron VE8RT wrote:
> > Thanks Don,
> >
> >       I've received a few helpful responses already, which I
> > appreciate.  I could do without the RTV, except I like it at RFC14
> > because its jammed into a tight space, and as you mentioned, its a RF
> > choke which wouldn't be critical.
> >
> >       For a very long time conformal coating has been used in my
> > field, avionics.  Its great stuff to reduce board corrosion in damp
> > environments, even if its just from condensation.  That is if its
> > applied carefully and the board and adjustable components and
> > contacts are well masked.  If it won't mess things up, when its
> > finished I'd like to apply conformal to parts of the board,
> > especially the underside of the board.
> >
> >       Back to the RTV on RFC14, there is a very small dab of it on the
> > bottom of the core, just to keep it upright.  Anymore than a small
> > dab would be a waste.
> >
> >       OK, future cores I'll leave alone unless the manual says
> > otherwise.  And conformal coating parts of the board can wait until I
> > look into this further.  I have spare cores and wire, and an
> > reasonably good LCR meter at work, I'll see what difference the
> > coating makes in the value of toroidal coil.
> >