[Elecraft] A couple more questions (toroids and soldering)

[Kenworthy, Edward (EDS)]

Thanks very much for all that Tom.

-----Original Message-----
From: Tom Hammond [mailto:n0ss@earthlink.net]
Sent: 17 June 2003 15:41
To: Kenworthy, Edward (EDS); elecraft@mailman.qth.net
Subject: Re: [Elecraft] A couple more questions (toroids and soldering)


GM Edward:

The following is personal opinion, and worth (maybe) whatever you'll pay to 
read it.

>Ok getting close to toroid time - thing is until I read this list I wasn't
>at all concerned, having wound some for the powermeter I built, but now...
>:-) Anyway. Can anyone confirm that spacing and getting the wire through
the
>centre is the important bit, the windings being tight is mostly for
neatness
>? Also, I was considering holding the windings in place using a splodge of
>glue from a glue gun - good idea or not ?

1. Wind your toroidal inductors with the knowledge that others will 
undoubtedly see them when you're done. The effort you put into winding them 
well, and neatly, will reflect well upon your building prowess later.

2. While it is probably not terribly 'crucial' that you wind nice, 
tightly-wound turns, having them laid on snuggly (is that a word?) will 
help to ensure that the windings will stay where you put them once you're 
done and using the rig. Take time to 'form' the wire around the body of the 
core AS you lay on each turn, pull the wire tight once it's thru the 
center, and then form the wire around the core again, in preparation for 
the next turn being laid on. It's well worth the added effort when all is 
completed.

3. Once the toroidal inductor is wound, TAKE CARE to space the turns out 
evenly around the core, following Elecraft's urging to cover 80%-85% of the 
entire core with turns. As you 'space out' the turns with your fingers, if 
you took care to keep the turns nice 'n snug, the spacing will also serve 
to further tighten the turns against the body of the core, for a real 
snazzy looking final product.

4. DO NOT waste time attempting to 'secure' the turns with ANY form of 
glue. If you did your job in the first place (see items 1-3, above) glue 
will NOT be required. A small bit of movement of the inductors, due to 
physical 'bouncing' of the rig is to be expected and should not cause 
problems for the inductors. Finally, gluing inductors almost always results 
in a real pain in the backside if/when you find you need to work on one of 
them. Just don't do it.

5. Exercise the utmost care when TINNING your inductor leads. Follow the 
directions in the manual and NEVER install a toroidal inductor until you 
have confirmed that the leads HAVE been well-tinned, and that they have 
been tinned close enough to the body of the inductor that when you pull the 
excess wire thru the PC board, you will still have tinned lead (and not 
enameled wire) INSIDE the plated-thru hole.

>On a related note - crystal cans. I've had no problem soldering wire to
>crystal cans, but as part of a process of continual improvement :-) I read
>the tutorials and advice on the Elecraft web site. One piece of advice
there
>was to use some extra flux. Uhm, my copy of the K2 manual makes it quite
>clear that using extra flux invaldiates your warranty ! Am I
>misunderstanding something ?

Different 'extra' flux!

The manual is referring to the use of liquid or paste fluxes as an adjunct 
to soldering to the PC board pads. The 'extra flux' referred to in the xtal 
can comments refers to possibly adding a bit of extra flux to enhance the 
solderability of the metal of the can itself.

This having been said, I would personally not advise using liquid or paste 
fluxes on any component of and Elecraft kit unless specifically directed to 
do so by Elecraft.

If you find that you can't solder to the xtal can, first check it for 
corrosion (VERY IMprobable), and then check the tip temp of your iron. The 
small xtal cans used by Elecraft should take solder like a man in the 
desert takes water! At worst case, you can always use a little steel wool 
or emery cloth to 'clean' the edge of the xtal can prior to soldering. 
Though I've NEVER found ANY of these steps to be required. Tin the side of 
the can first, set it aside. Tin the end of the wire to be attached. Lay 
the wire against the tinned spot on the xtal can, and touch BOTH with the 
tip of the iron. That's all that should be required to effect to nicely 
'sweated' joint.

73,

Tom Hammond   N0SS