May 8, 2012

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Project Building Tips

So how do you go about building up a project that you see in QST or QEX magazine?  Is it an excruciating effort to collect the parts and get started?  Or perhaps do you see it all as a big adventure and dive into things before evening thinking through some of the issues about to be tackled?

Well, the discussion this week may give you some ideas for closing the loop on how to get your next new project built up.  Whether it's a source of parts, some old tools used in new ways, or just some ideas you might get from the years and years of bench experience that Joe, George and others bring, we pretty much guarantee that you'll come away from the session with some fresh ideas that you'll be itching to try out on the bench!

73, George N2APB & Joe N2CX

Audio Recording ... (Listen to MP3 recording)

Text Log ...

?<20:11:25> "W2AEW - Alan": Do you have a source for one of these circular punches?
?<20:11:45> "George - N2APB": Yep, it's a Harbor Freight tool. Will get the number.
?<20:12:50> "Pete - WB2QLL": I make pads out of the fingers of old pc cards. Just cut 'em off and make 'em as long as you need.
?<20:15:17> "George - N2APB": I also use a small, 4" high-speed hobby circular saw (again from Harbor Freight!) to cut long, thin strips of the pcb material, then cut off little square pieces, about 1/8"-square
?<20:16:44> "Mike WA8BXN": The harbor freight punch that makes the round pads can put a little "peak" on one side of the pad, be sure to put the peak up when gluing them down
?<20:17:10> "Mike KD5KXF": or file hat point off... if filed flush you wont get that peak
?<20:18:03> "Ray K2ULR": Everclear (grain alcohol) might also be a good solvent.. (good old white lightning). :)
?<20:18:09> "Kelly K4UPG": What is best way to place the pads to keep from touching them with my fingers? Do you use tongs?
?<20:18:48> "Joe N2CX": http://www.njqrp.org/islanderpadcutter/index.html
?<20:19:00> "Mike KD5KXF": I usually have superglue covering my fingers so it isnt an issue Kelly
?<20:19:12> "Mike WA8BXN": I use tweezers/tongs so I don't get the super glue on my fingers. once positioned i press down with a small screwdriver
?<20:20:51> "Joe N2CX": http://www.njqrp.org/islanderamp/Islander%20Amp%20Manual%20v1.pdf
?<20:22:38> "Mike KD5KXF": Do you do a lot of preplanning before gluing Mikey?
?<20:22:43> "Sam KD0QJL": Harbor Freight in my area does not have a hand punch but Grizzly does. Here's the link http://www.grizzly.com/products/Portable-Hand-Punch/G8780  . I use it and it works great.
?<20:23:13> "Frank N3PUU": those are often referred to as "roper whitney" hand punches
?<20:23:47> "Joe N2CX": Harbor freight does not always carry the hand punch Northern tools is another source.
?<20:24:23> "Mike WA8BXN": I have sometimes sketched out a section of circuit on paper before doing the pads. like each stage from the schematic
?<20:24:54> "Pete - WB2QLL": There is a difference between brand name and off brand cyanoacrylate!
?<20:25:34> "Larry - W2HHV": This is a neat audible continuity checker for verifying isolation between adjacent pads: http://www.carnut.info/star-parts/pcbs/buzzer.htm
?<20:25:39> "Joe N2CX": There are test poiins shown on a pc board half way down the page
?<20:27:37> "Joe N2CX": One can also put more circuitry on the bottom side of the board but use standoffs!
?<20:29:03> "Mike WA8BXN": I have never had a worry about shorts between adjacent pads
?<20:33:25> "W2AEW - Alan": Be careful with NiCd - very low internal resistance!
?<20:33:31> "Mike KD5KXF": if you are cutting rectangular pads for ic's and using saw or similar for the separate traces it is good to use a DMM to check for lack of continuity between them
?<20:34:40> "Mike WA8BXN": What about a low voltage dial light with appropriate current --- like putting one in series with a crystal, provides protection and indication of high current draw
?<20:38:07> "Joe N2CX": <http://www.qrpme.com/?p=product&id=MEP>
?<20:38:24> "Joe N2CX": That was link for ME PADS
?<20:41:01> "Joe N2CX": Rex's grid of pads board is mint-tin sized
?<20:44:30> "Curt WB8YYY": K3PEG is the well known guru for extreme manhattan of 2n2 and Islander
?<20:45:41> "W2AEW - Alan": Take care with RF circuits with plug boards - lots of parasitic capacitance and inductance with them
?<20:46:23> "Curt WB8YYY": yes here for example -- http://www.learnmorsecode.com/k3peg.html
?<20:50:09> "George - N2APB": Great collection of John KE3S use of copperclad in homebrew projects ... http://www.midnightdesignsolutions.com/atlanticon/atlanticon%202003/pics/hires/cawthorne-table.jpg
?<20:50:24> "Mike WA8BXN": cut boards with a heavy duty paper cutter?
?<20:50:51> "W2AEW - Alan": A fine toothed blade in a tabletop scroll/jig saw works well too
?<20:50:59> "George - N2APB": Another view of Jim Kortge's manhattan style construction ... 2N2/30 transceiver: http://www.midnightdesignsolutions.com/atlanticon/atlanticon%202003/pics/hires/2n2-30-1.jpg
?<20:51:59> "George - N2APB": And Nancy Feeny NJ8B projects of copperclad construction ... http://www.midnightdesignsolutions.com/atlanticon/atlanticon%202003/pics/hires/feeney-project-table-2.jpg
?<20:54:11> "Joe N2CX": WB8RCR has some software to do panel artwork
?<20:59:24> "Joe N2CX": Terry WA0ITP has a good presentation on doing custom panel artwork on his website www.wa0itp.com
?<21:01:48> "Joe N2CX": I believe that Dymo labels with clear backing and white lettering are available.
?<21:04:11> "Mike WA8BXN": if you are printing on clear film and can print the black background around clear (white) lettering, could you spray the back with white paint?
?<21:05:22> "Curt WB8YYY": another nice link with MEsquares - http://aa7ee.wordpress.com/2011/07/24/the-wbr-a-simple-high-performance-regen-receiver-for-40m-by-n1byt/
?<21:09:38> "Howie - K3HW": Are the "L" brackets for BNC's, connectors, and other panel mount devices available from a vendor or are they homebrew?
?<21:10:29> "Mike WA8BXN": you can make L brackets from aluminum angle stock cut to length
?<21:16:59> "Terry WB4JFI": I use a five-drawer plastic roll-around cart, with audio/video in one drawer, RF adaptors in the next, DC adaptors and common walwarts in the next, short audio cables in the next, and short RF cables in the last. The cart sits under my bench, but can roll our for easy access.
?<21:18:02> "Terry WB4JFI": RF step attenuators (surplus or homebrew) are also very nice accessories.
?<21:20:11> "Mike WA8BXN": What is the story about the last picture - Holding down the soldiering iron cradle?
?<21:21:17> "George - N2APB": Well, the soldering iron holder has strong double-sticky tape (or velcro) to hold it fast to the table. Otherwise, the holder will move around a lot when replacing the iron into the holder.
?<21:22:05> "George - N2APB": Thus when you have a messy bench (such as mine), you don't push the junk around all over the table.
?<21:22:09> "Mike WA8BXN": Thanks George, good idea!
?<21:23:36> "Howie - K3HW": I use waxed dental floss for lacing and bundling cables using the old fashioned "wire harness" method.
?<21:25:56> "W2AEW - Alan": Those litttle stray pieces of shield wire are known as Murphy's Whiskers
?<21:26:27> "George - N2APB": Ha! Yes, Bill (of SolderSmoke fame) mentioned that too. How true and aptly-named!
?<21:27:03> "Mike KD5KXF": Great presentation, thank you very much!!!
?<21:27:15> "Frank N3PUU": thanks guys, that was a fun one!
?<21:27:35> "Howie - K3HW": Great session
?<21:27:45> "Terry WB4JFI": thanks guys! another great discussion
?<21:28:28> "Russ G3OTH": Thanks George and Joe 73
?<21:28:34> "Ray K2ULR": 73
?<21:28:38> "George - N2APB": Dental floss for wrapping cables ... great idea Howie! (Hopefully it's unused floss?)

 


SESSION NOTES ... "Project Building Tips"   [Photos and diagrams yet to be added ... GH]

 

      First things first – what is project goal?

 

      Copper-clad base board for prototypes

 

      Grounding

Copper-clad board ideal

      Making "Manhattan Pads"

Hand punch

 

 

Tin snips for square pads

 

K8IQY nibbler method

ME Pads

 

 

      Attaching Manhattan Pads

Keep it clean  +  Super Glue  (cyanopacrylate)

 

 

      Cleaning copper-clad pcb

Scotch-brite

Solvent

rubbing alcohol vs “Heet” fuel additive 95% alcohol

      Design for Testability

Plan ahead

      Adding test points to circuits

Low Z points

Diode detector

Hi R resistor for bias checks

      Alternate power supplies

Current limited supply

 

 

Alkaline AA cells (8)

 

Carbon-zinc cells have more of a current limiting capability.

 

Assortment of very convenient battery holders ... (L-to-R): 10 C-cells, 3-AA, 10-AA

 

 

2-AA cells for 3V supply

 

3 AA NiMH

4 AA Alkaline

      Making test points accessible

Test points exposed for easy measurement of control loops,

Voltages on the supply bus, processor or board state, etc.

 

 

      Building circuits in sections

 

      Using prototyping plug board

 

Temporary becomes semi-permanent

 

      Make modular, standard circuits

Don't reinvent the wheel

      Cutting panels & chassis (plastic, pcb, aluminum, mint tins)

Knives, step drills, ice, wooden block

      Marking front panels for cutting

      Making labels for controls

      Putting everything on a board during prototype (rotary encoder, LCD, other boards)

Like open-face sandwich

Easy access

Minimize bench clutter

      Putting feet on a prototyping board

Standoffs to work on both side

Rubber feet prevent shorts

 

      Mounting coax connectors

L brackets

 

Ring lugs

Solder

      Mounting other connectors

 

      Routing cables (tie-downs, signal sensitivity)

 

      Locating power supplies/converters

Noise, heat ground loops

      Using wiring in lieu of module standoffs

 

      Effective use of (readily available) standoffs

Pick a type and buy in bulk

Ugly construction

Air-wiring

      Standard connectoring for DC power on the bench

 

 

      Standard/test cables to the work area: antenna, DC power, meter probes, audio cables (3.5mm, RCA,…)

 

 

      Box o' adapters when all else fails

 

      Keep a project notebook

Note successes and failures

Don't skimp on notes

      Photographing intermediate progress – for documentation, for requesting help

      Preparing the ends of coax cables

          Shrink tubing for strain relief

          Directly solder Teflon coax

      Holding down the soldering iron cradle


REFERENCES

1. K8IQY "Manhattan Madness" page construction techniques and projects ... <http://www.k8iqy.com/>

2. Ken Locasale WA4MNT Construction Techniques ... <http://www.qrpbuilder.com/>

Tips for drilling holes in thin metal .. <http://www.qrpbuilder.com/downloads/sheet%20metal%20drills%20a.pdf>

Chassis from PCB material .. <http://www.qrpbuilder.com/downloads/pcb_chassis_a.pdf>

3. K7QO projects and techniques  ... <www.k7qo.net>

PC board enclosures ... <http://k7qo.net/enclosure_tutorial.html>

4. Sources for copper clad board:

Various Ebay dealers

Far Circuits ...  at Dayton

Circuit Specialists  ... <http://www.circuitspecialists.com/>

5. W1REX website ... <http://www.qrpme.com/>

ME PADS IC and SMT IC breadboarding boards ... <http://www.qrpme.com/?p=product&id=MEP>

ME SQUARES small pcb squares for Manhattan Construction  ... <http://www.qrpme.com/?p=product&id=MES>

 

 

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