[Hammarlund] SP-600 RF Deck

[Kevin Ward]

I was the shop manager of an avionics repair shop for many years.  We
used desoldering stations with the hollow heated tips.  I forget who
made them but I believe they were bought out by Sylvania.  They had a
push button on the iron handle that activated an electric vacuum pump. 
They were outstanding, but as someone else mentioned, periodic cleaning
of the tip and suction tube was mandatory.  Even so, on some stubborn
multi-layer boards it was necessary to use the desoldering tool on the
back side of the board, while simultaneously applying a soldering iron
to the same pin on the top side of the board.  A strong light shining
through the board was a big help here.  This technique markedly reduced
the "heat" time and was actually better for the circuit board!

I heartily disagree with the practice of reusing desoldered parts,
except in very non-critical or hobby applications.  The logic is this: 
The process of soldering the part in place stresses the device. 
Desoldering and resoldering stresses the part twice more.  Each insult
compromises the reliability of the device, regardless of what it is. 
Most avionics manufacturers absolutely forbid the process. In fact, they
recommend clipping each lead with a pair of "dikes" and desoldering each
lead, one-at-a-time, pulling out the pin remnant with needle-nose pliers
while the solder is still molten. 

"Borrowing" and returning a device to a donor equipment is only asking
for later troubles.  If nothing else, think of the abuse the circuit
board takes.  Most of these parts are cheap.  Use a new one and give
yourself a break; leave the working equipment alone. 

Kevin  N2IE