[time-nuts] low noise multiplication to 100 MHz

EWKehren at aol.com EWKehren at aol.com
Tue Jan 26 10:17:23 EST 2016


Chuck
Thank you for your advice, I will print it out and when needed experiment.  
We use SMD.s and two of our tem members are very good at it, I do limited 
stuff  and have some tools but also a macular hole in one eye. In designs I 
try to stay  with solder able SMD's and we have projects like the AD9913 
which gets to the  limit what I will consider. I did not do the soldering.
Bert
 
 
In a message dated 1/26/2016 10:00:51 A.M. Eastern Standard Time,  
cfharris at erols.com writes:

Hi  Bert,

I have noticed that if I have the right magnification,
I can  do amazing things.  Even the tiny age related
tremors that naturally  occur in my hands reduce with
magnification.  The brain is a  marvelous  servo mechanism.

Get a good 40x-80x zoom stereo  microscope meant for
dissection, the type mounted on a boom, and I would  bet
you too could deal with the small surface mount parts.

When I  build with SMD, I always put all of the parts on
the top side, and use  solder paste.  I used to put lots
of tiny dots out with a syringe that  works a lot like a
caulking gun... only smaller.  But I found that  simply
drawing a thin stripe of paste across the SMD pads
on the board,  and then setting the part on the paste,
works just fine.  The solder  draws towards the pads, and
leaves the space between the pins clear.   Occasionally
there will be some tiny balls sitting between the pins,
but  they clean up when I clean the board with alcohol
and a brush...not that  they hurt anything anyway.

The chips self center while they are  floating on the
molten solder.  No need to touch them with a  soldering
iron, or anything else.

I use a lab grade hot plate to  bring the board up to reflow
temperature.  And I am off to the  races.

For disassembly, I use an IR underboard heater, and a
hot air  source... about 1/8 inch diameter, and move it
around the pin area until it  melts, and then lift the
part free.

To put parts on an already  populated board, I pre heat
the underside of the board to about 1/2-2/3 the  way to
the solder melting temperature, and use a little gentle
hot air  source to head the pads the rest of the way to
molten.  No need for  soldering irons.

Practice on junk boards until it becomes  natural.

-Chuck Harris

Bert Kehren via time-nuts wrote:
>  We have looked at the LMK devices but with my 74 years would not try  to
> solder it. There are other neat parts out there but again who is  able to
> solder  them.
> Bert  Kehren
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