At 01:58 PM 2002/01/23 +0100, Alberto di Bene wrote:
Larry Kayser wrote:
> If you can get the 51, grab it, if you can get the 52, 53 or 54 grab the
> highest number you can. each one is better than my 9250. The higher
> numbers let you use a lower reference frequency for controlling a higher
> output frequency , ie much greater than .45 of the reference frequency for
> the 9250.
>
I have in my drawer an AD9854, obtained as sample from Analog Device.
Problem is, I am horrified at the very thought of having to produce a PCB
for it, let alone soldering it.... SMD make life difficult for the
hobbyists, I am
afraid.....:-(
Alberto:
I had one of the kit G4JNT boards and I looked at it and nearly died with
fright. I have vision limitations here, and my stiff old fingers are not
much good anymore....but I borrowed the some optics, from my local
physician and I practiced on some dead MODEM and LAN Cards and I bought
some special tiny tips for my Ungar soldering iron, some special tiny
solder, some special liquid flux (for electronic work) and I managed to get
the 9850 into the right place. I put in several hours with the lamps
moving them around inspecting the slots between the foils and the now
soldered wire pins. I found one bad one, and with about half an hour I
managed to do the trick of cleaning out the bridge. I had zero problem
getting the SMD parts into place after getting the 9850 stuck in the right
place. I had to use three different B&L eyepieces to see the 9850 stuff,
and it took practice to miss the eyepiece and hit the 9850 wire pin with
the soldering iron, but I did it and it works.
The biggest trick here, was to get the PC pads for the 9850 tinned and in
place and then to hold the 9850 still while I got the three of the corners
soldered down, once that was done it was smooth sailing so to speak. The
process is to setup a work facility, old plywood and drywall screws so the
work is at the right height when I am sitting down and then to make up the
bits and jigs to hold everything in place. I made good use of my Dremmel
tool to fabricate the little clamp bits etc. One thing I did was make a
place in the box I built for my table here was a place to put my chin so I
could hold my head still. This was very important for me. Yes it was
certainly not my choice of activity but I did get it done.
My sense is that if I can do it almost anyone can. I used to watch a guy
who did actual repairs to the dice in IC's. He used to put spare gates and
transistors around the outside of experimental IC's and then when an error
was found he would "repair" the IC, now he had it rough. I figured if he
could pull that off I could repair anything built with those things hi.
Lets put it this way, if you try and succeed then you have an AD9854 with
its I and Q outputs, and I would prefer you to have a 9854 with those
capabilities hi. Alternatively you could send the 54 to Andy and he would
I am sure get it going, or as a last case you can send me the 54 and I will
take a run at it. You have options hi.
Larry
VA3LK
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