[Qcwa] Bragging Rights (A good thing!?)
WILHITE, JIM
[email protected]
Mon, 8 Jul 2002 15:48:28 -0600
Bob and Jay,
One of the things taught in technical electronics school is logic. It ha=
s that name for a reason. If anyone will approach repair with common sen=
se and logic, much can be done. I have often heard teachers in lab state=
to the students: "If you break it, we will fix it" (meaning the test equ=
ipment). =20
Decidedly SMT requires a much steadier hand than I have today, so I don't=
approach it unless it won't be repaired at a shop. I have small hands b=
ut the way I use them, you would think they are hams. For that reason I =
use the old and classic gear and work on it quite regularly. But as for =
test equipment you guys are right on. I have a URM 25 signal generator w=
hich has calibrated output (25 bucks at a hamfest and I had to work on it=
to get it going). The calibrated output is only necessary if you desire=
lab results or measurements when aligning. It has two outputs, high lev=
el which I hook to my counter and the calibrated output which goes to the=
receiver under test. Sure it wanders and I have to keep my hand on the =
frequency knob, but so what. The approach Jay mentioned of building a si=
mple one does not have the wandering problem and is cheap and easy to do.=
Just keep the input below the AGC/AVC level and you can't go wrong ass=
uming you are touching up a circuit that has been aligned before. Add to=
that an audio oscillator which are cheap and plentiful. Hook your gener=
ator to the counter, set it, then move the output to the receiver you wan=
t to test. =20
With the soldering station I would add some dental tools (picks, one or t=
wo), two pair of hemostats, tweezers, a good collection of screwdrivers, =
small wrenches (a pouch of ignition wrenches can be bought from Sears), a=
lignment tools and good cutters, needle nose pliers, allen wrenches, and =
nutdrivers. Pick up phillips and flat blade screwdrivers that hold the =
screw for upside down vertical or horizontal insertion.
I am not sure about using solder suckers on SMT since some of the diode=
s, logic chips, FETs and other components are very sensitive to static el=
ectricity. Solder suckers can cause static electricity. In its place I =
would use the wick, and be sure it is a very good brand (not Radio Shack)=
. Also remember to work on a surface using techniques that reduce static=
electricity, especially around SMT, CMOS and the like. Sometimes the mo=
st challenging situation is finding the parts. Many parts in modern radi=
os are not available in the common market and once the model is discontin=
ued the parts production does as well, so you may have to be resourceful =
as stated.
Have one very good multimeter like a Fluke to calibrate others you may us=
e against it as a standard, (less than $75 brand new with .25% accuracy).=
I use a Simpson 260 and an RCA Senior Voltohmyst most of the time. Som=
e circuits utilize very small voltage changes and they are difficult to m=
easure with an analog. The scope is a very nice addition to any bench, b=
ut not necessary in all applications. Not that I haven't had to use one =
to find a particular problem from time to time, but not much of the time.=
I have a dual channel 50 Mcy. version, brand is not important and aroun=
d most circuits calibration is not either.
I have the MFJ 259B and it is a very nice piece of equipment for ballpark=
measurements. It does a lot but, used in tuned circuits, it will not gi=
ve sign of X. For all it will do within its limitations, I do recommend =
it especially for the counter and its ability to measure coax loss, fault=
s and length. =20
Depending on frequency, accuracy can be an issue. And everything I have =
falls into the accuracy category that amateur radio requires. Most of it=
will not fit the bill in commercial service, but kind of accuracy is not=
commonly required in amateur radio. So I go with your assertion. The co=
unter should be checked for accuracy if used to set transmit freq. and sh=
ould be checked regularly. The variable temp. soldering station is a must=
. Keep that tip clean for maximum heat transfer and wipe it off every ti=
me you use it. =20
You guys are surely on the right track here and it would be interesting t=
o read some of the problems you have encountered. In my case the most ch=
allenging problems can be disassembly and reassembly after repair so it i=
s best to have the manual close by. =20
Altogether I have spent less than 350 dollars for my equipment over a per=
iod of about 10 years including the 259B. Watch those hamfests, test equ=
ipment is all around and mostly cheap. Sure wish I had a sweep generator=
though. Good posts.
73 Jim
de W5JPW
Quite impressive, and you've obviously thought this out. You
sound like an accomplished tinkerer (and I use that term in only the
most complimentary sense)! I have in the past been able to repair all
my own gear, and I've worked on Surface Mount devices with little more
than a low-wattage iron, a pair of tweezers and not a little luck. It
is, as you say, very satisfying.
Unfortunately, for me, many times I've found things that I
absolutely cannot match with the junk box, or custom ROMS, or some
proprietary LCD display driver IC that I can't do much with. I can
recall spending a good 16 hours working out an old burnt out display and
soldering in all 55 pins of the new, and feeling I accomplished
something at the end. I still hated every minute of it till the end,
and begrudged the time it took.
It would be interesting to hear, from the sagacious among us,
just what they feel comprises a minimum "bench" setup. You'd already
mentioned a variable Soldering Station, VTVM (or decent Fluke type DMM)
scope and signal generator, which I have, but I'd add a Freq Counter,
dip meter (or equivalent) and a variable DC power supply. You know what
I really like? Those MFJ antenna Analyzers. Not just for the stated
use, but because they incorporate a Freq Counter and Dip meter as part
of the package. For less than 250 bucks, that's quite a lot.
I'd also think we could hear some groups on the accuracy needed
in those test instruments. I've worked with people who scorn anything
without accuracy approaching PPM levels, and with others who say
whatever you have, estimate when needed (I tend to lean towards the
latter).
73, Bob, K2PI / ON9CPI
Brussels
-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of J Craswell
Sent: Monday, July 08, 2002 6:14 PM
To: [email protected]
Subject: [Qcwa] Bragging Rights (A good thing!?)
I suppose what I am trying to say and what I hope people will think
twice about is that my bench equipment. i.e. the gear needed to do this
is not that extensive. If we accept that a typical Short Wave Radio
costs a grand then the tools to work on it or build new stuff ought to
be less than that. I'm easily way under that. And I think my modest
set up is just that. A modest
bench. An adjustable temp iron is really not that expensive. Can we
stick
to our 100 watt solder irons? No, of course not. The cost of solder is
low a solder sucker (ditto) tweezers (ditto) Now the test equipment can
be anything you like to use. I've got one of those DVMs (From Radio
Shaft) and I have an old beat up signal generator from HP but a guy
could build his own (As I did) with an Analogue Devices DDS chip for
next to nothing. BTW the HP was a couple hundred bucks because someone
dropped it on the face and
bent the handles. The use of a scope is I think not so exotic as it
might
have been in the 50s. What is important is that the price of a good
used scope is pretty amazing. I bought a 350MHz Tektronix scope for a
couple hundred bucks and love being able to "see" what's going on.
Being alive today and be able to own such super science equipment for
next to nothing is a big plus! The good old days? 500 KHz scopes and
6V6s? No thanks!
I think being able to fix your own gear is a plus. Is it for everyone?
Well no - but I don't believe it ever was. What I think we should
promote
is that it "ought" to be for more folks. (In my opinion) I don't think
we
should make general statements that no one builds their own gear or that
no one can fix this new stuff like the good old days. Heck I remember
thinking the new parts like Transistors and ICs were too Hard and how
could anyone work on that junk? Nuvistors were good! 723 Regulators
were bad. <grin> The problem as I see it is that new hams not knowing
any better will nod their heads and turn into Appliance operators when
this is the last thing we need. If you step back and look at it this
era we live in is actually pretty nice with the mentality that anything
broke is Landfill. I can't tell you how many items I've gotten for
little to nothing and am using everyday. I've got a Lightning blasted
FT-847 that works like a charm. A FT-100 that had a bad -9 volt supply
also working like a charm. It's all powered by ASTRON supplies that
were "burned up" My XYLs radio is another
lightning special. That one was really toasted but a new audio circuit
(The real one cost too much so I glued in an Audio chip I had in the
junk
box) and some parts in the front end and some new coils put it back on
the air in good fashion. Heck I may never buy anything new again as
long as people break stuff and want to toss it! <grin> My cost on a
most of this was the gas to drive over and pick it up and the
replacement parts. Did I spend a lot of time on it? Some I did others
not much. If I was charging $75 an hour as some techs do I think I
would still be way ahead. But I don't charge $75 to fix my own stuff
<grin> And it's fun and gives you a little bragging rights which I hope
my fellow QCWA members will do more of. Bragging about being able to
copy 20+ wpm is good. Ditto designing your own radio etc. Isn't that
one of the goals of the part 97 regs? Increased operator skill and
technical ability?
73 my friend! de Jay W0VNE
p.s. KA0KLV reports my repair job on the little Icom is still working.
(Got my fingers crossed) He is buying lunch for sure!
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