The Art of Soldering (PL259 to RG8/U)

The other day I finally installed the 2 meter J-Pole I’d bought late last year.  I made use of a run of coax that had been used for a dipole antenna, and I had cut the run shorter to use the minimum amount of cable between the shack and the antenna.  So, I had to solder a new connector to the feedline in the shack.

Technically, it’s not RG8/u, but rather RG/213U, which is the modern part number.  Still, old time hams have been calling the cable RG/8U for decades, and as both part numbers look the same from a few feet away,  a rose by any other name ….. to quote the Bard.

Attaching the common PL259 UHF connector to this 1/2″ cable looks simple, until you actually try to do it.  The cable is thick, and not very flexible, and difficult to handle.  The operation of striping the insulation and tinning the copper braid is a messy operation with the thick cable fighting you all the way.  Over the years, I’ve figured out a method of taming the beast, and produce a good strong and perfect electrical and mechanical connection between the ancient connector and the coax.

I really don’t know why new amateur (and CB) gear continue to use this relic from WWII, but the PL259 (and it SO-239 mate) just refuse to die.  You’d think that the superior N type connector would have supplanted it by now, but alas no.  Not that the N connector is any easier to attach to coax, but it is simpler to solder to, and has a lower SWR bump, especially above 30 Mhz.

Anyway, the first thing I do is to strip about 1.5″ of the outer insulation off of the cable to expose the copper braid.  Normally, you’d then cut the braid back to size (about 1/2″) and the tin it, however that will leave rough loose ends of braid about, ready to end up inside of the completed assembly to short it out.

So what  do is to tin about an inch of the braid from the outer insulation towards the end of the cable.  First smear a good amount of rosin flux on the braid and then melt a thin layer of solder on it.  Use a Weller soldering gun, NOT a wimpy pencil or iron.  A 140 watt or higher gun is ideal, though I have been able to get good results with my old 100 watt Weller Junior gun.

After tinning the braid, I file off the excess solder to leave a smooth evenly tinned braid with no solder lumps.  Now we will cut the braid back to 1/2″ in length.  The ideal tool to use here would be a tubing cutter.  I’ve used  a pipe cutter for this with good results, but you have to be careful to only cut through the braid, and not all the way though the insulation to the center conductor.  I’ve also got good results with a hack saw, or a jewelers saw.

Next peel away the rest of the braid to leave the center insulation and conductor.  About 1/16″ from the end of the tinned braid cut away the center insulator to expose the inner conductor.  Twist this some and then tin the end and cut it just long enough to stick out of the connector.  Use the connector as a size guide.  Now slip the connector clamping ring over the cable (with the open end towards the end of the cable!), and screw the connector on to the cable.  You should see the tinned braid through the four holes though which you will solder, and the center conductor should be sticking out the front by at least 1/8″.

File or sandpaper the connector where you will be adding solder to remove any corrosion that would result in a bad solder joint, and then wipe on some rosin paste flux.  Use a small vise to hold the cable while you solder the connector to the cable at the four body holes, and the center connector.  Trim the excess center connector off, and touch up the soldering here.  Now screw on the clamping ring (You DID remember to slip it on on the cable the right way didn’t you?), and the job is done.  A thing of beauty forever.

 

Computer Build part 2

So my parts arrived and I’ve done the initial POST test.  Hurrah, it all works.  I’ve downloaded the current Alpha build of the future Kubuntu 20.04 LTS (the final release will be sometime in April, as the release version name indicates).  That seems to work too.  I’m still not too sure about the video card though.

I bought two different cards, the first was a 2GB Radeon R7-250, and the second was a EVGA GeForce 8400 GS.  Both are older, single slot cards that while no longer recommended for gaming, will handle the usual office applications and Youtube videos just fine.  They both also have enough resolution for CAD work, so I’m covered here.  I wasn’t interested in building a gaming rig.

The Radeon card came from Ebay, as a Dell overstock item.  It has two outputs, one DVI and one Displayport.  In theory, it should drive both outputs, but so far I haven’t been able to get anything out of the DP  I’ve read online that the card defaults to the DVI output until a driver is loaded, and at least in my case the MB bios does not display anything out the DP, even when its the only one connected.

I haven’t yet tested the GeForce 8400 yet in this regard.  Obtained from a B stock sale on EVGA’s website (for only $10 and free shipping), it has three outputs, one HDMI, one DVI, and one VGA.  With monitors connected to the DVI and VGA  ports I only get output under the BIOS setup from the DVI, but I didn’t try that with ONLY the VGA connected.  I do get dual head operation under Kubuntu, so even the open source drivers can handle this.  I don’t yet know if I can drive both digital outputs (DVI and HDMI) at the same time in dual head mode, I’m still waiting for another HDMI cable in the mail to try that.  I did get an HDMI to DVI adapter, but it won’t plug into the card along side the DVI cable as the sockets are too close together.  I can always use the DVI and VGA outputs, as my monitors will handle that, but I’d rather not use the VGA inputs as they probably lose a little bit in signal quality over the Digital inputs in full HD resolution.

I also have the older Nividia dual head card that’s in my current computer.  It only has 512gb of ram, but does drive dual DVI outputs to full HD.  It’s good enough, but I was hoping to get a cheap, more modern GPU running on the new machine.

Now to answer the question of why I chose the other stuff that I did.

1: CPU:  Short and simple, I’ve always liked AMD for being a bit better in the bang for the buck, and for being a smaller target for the malware writers.  Their new Ryzen Zen processors are currently the best price vs performance available, sorry Intel.  The Zen 2, Ryzen 5 3600 is actually at the bottom of the current heap (except for the Ryzen 3 3200G, and the Ryzen 5 3400G APUs).  I drew a $250 line in the sand, and the CPU I picked clocked in at $180.  The next one up was the slightly faster Ryzen 5 3600X, offering a bit higher base and boost clock rates, but not worth the extra $50 IMHO.  The Ryzen 7 CPUs which have 8 cores and 16 threads (vs the 5’s 6/12) start at about $310.  If I ever need more power later on I can upgrade to this point, and then there are the Ryzen 9 processors that go up to 12 or 16 cores!

2: Motherboard:  My price line in the sand was about $100.  This pretty much limited me to a B450 chipset, and a uATX format, but I’d already settled on the smaller sized board because I wanted to use the case that I’d salvaged from an old Lenovo machine.  There are plenty to chose from with these parameters from MSI, Gigibyte, ASRock, and ASUS.  Most of these will have one M.2 PCIex4 SSD slot (usually with this chipset if there is a second M.2 SSD slot it will be SATA3 based).  I chose the MSI board mentioned as it fit my price range, and also included board headers for both a COM port, and a PARALLEL port.  Both of these are useful for driving micro-controller development tools.

3: Memory:  As I wasn’t going to sink extra money into a high end video card, or a more powerful processor, I decided to get the most/best memory I could afford.  I budgeted about $150 for the ram.  I did run over that by $10, but spent only $80 on the MB, so we’re not over budget.  Crucial recently (just a week before I placed my order) announced a new line of their Ballistix gaming memory in 2667, 3000, 3200, and 3600 mhz speeds, with and without RGB LEDs (WTF?).  AMD recommended 3200 mhz speed ram as the sweet spot for the Zen 2 processors, so I decided to go with that.  I ordered a 32gb kit (two 16gb modules) which is probably overkill by double what I REALLY need.  However, I do intend to run Windows 10 in a VM under Linux, and having the cores and ram to throw at it I’ll be able to run any micro controller development tool that isn’t available for Linux in a large enough sandbox.  Atmel Studio, that means YOU (you G-D resource hog!).

 

 

Building Computers

First of all, I’m sorry for being off the blog for an extended period of time.  I’ve been recovering from mitral valve repair heart surgery (in November)

Since 1995 or so, my ham shack personal computer has been one I’ve built from purchased parts, rather than an off the shelf machine.  During this time I’ve mostly used AMD processors, though a few machines did use Intel CPUs.  My current computer is a factory reconditioned Dell purchased from Ebay (Intel Core-i7), although it’s been upgraded with a new video card, power supply larger hard disk, and an SSD boot drive.  (Running Kubuntu Linux, it has the net-name of “ThePenguinInTheDell“)

The first PC I ever built was an upgrade to a PC-XT clone.  On that one I changed out the mother board for one with an 80386SX processor (I later moved everything into a larger case).  I then progressed to an AMD K6-233 in an AT Tower case, later upgraded to an Intel Pentium III-500 (mother board swap).   My next build was an Intel Pentium-III 833mhz this time in an ATX format ( later upgrading the processor to a 1 Ghz version). The next few builds were AMD Athlon and Athlon-64 based, with the final in this series using the Phenom-II 4 core processor.

Building your own computer might sound like rocket science, but it’s not.  The only tools you will need will be a #1 Philips screwdriver, and maybe a suitable sized nut driver.  An anti static wrist strap (which might be easier to use on your ankle) is also a good idea.  The hard part is in selecting compatible parts that will actually work together.  Obviously you must use a motherboard that has the socket and chip set that is compatible with the processor you intend to use.  The on board BIOS version must support the version of the processor, or you will need a way to update the BIOS.  You must also select suitable memory.  Any motherboard purchased today will be using DDR4 memory (unless you are building a ‘retro’ machine with an older processor and motherboard).  Getting the right memory process isn’t enough, the speed, voltage, and timing parameters must match the processor and chipset being used.  Sometimes memory that works on an Intel board won’t play with an AMD one (and visa versa).  If you buy your memory from Crucial, their website can help select the correct modules for the motherboard/process you are using.

Recently I decided that it was time to look at moving on to newer tech in the computer department.  AMD now has their Zen Ryzen processors in the third generation, with the fourth gen parts due out this summer.  The Ryzen 5 3600 processor I selected is a 6 core, 12 thread CPU with clock speeds starting at 3600 Mhz, and capable of being burst mode, and overclocked past 4 Ghz.  I selected Crucial’s new Ballistix memory at 3200mhz speed, getting 32 gigabytes (two modules).  Ebay provided a nearly unused M.2 256gb SSD for the boot disk, and I’ll probably transplant the 2gb SCSI III hard drive from my current computer to the new one (which contains all my user data files).

I selected an MSI B450M pro-vdh-max mother board, and I had a suitable mATX mini tower case salvaged from an old Lenovo Think-Center computer.  I know that Chineseium computer cases can be had for cheap, and the new case designs do offer improvements in air flow, and cable management, but the old Lenovo case is a ‘looker’, and it sports two 5.25” drive bays suitable for an optical drive, and a built in SD card reader / USB hub.  I had both of these items salvaged from previous computer upgrades.

The final item needed was a new video card.  I could use the current 256mb dual DVI PCIe card in my current computer, but I found an EVGA “B” stock Gforce 8400 GS on sale (on EVGA’s website) for only $10, with free shipping.  This card sports 1GB of memory, and DVI / HDMI outputs.  It will take an adapter thing-a-ma-gig to connect the HDMI output to my monitor’s available DVI or DP input, but otherwise it should work fine.

Kubuntu will release their 20-4 LTS version sometime in April, and that will be the OS I’ll install on the new PC.  In the meanwhile, I’ll be testing everything to make sure it all works.   I’ve already managed to do the initial power up and POST tests.  It all worked, except for the AMD R7-250 video card that I had originally planed to upgrade my current machine with (to fix a driver problem with the Nivida card).  It seems that this AMD card defaults to the DVI output, and won’t drive the DP output without the proper driver setup.  The motherboard BIOS doesn’t know how to talk to the DP output.  I could probably get this to play eventually, but I now have the option of using a Nivida card that should work.

 

Heathkit GC-1006 Clock Assembly Log

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Packed in a plain cardboard box inside of a Priority Mail shipping box, awaiting my attention.

P1020648.JPGOn top the famous Heathkit assembly manual, and a note congratulating me on my purchase.  Strangely enough, this is called a “First Edition” kit, even though it’s been in production for some two years now.

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Inside, several envelopes containing the parts.  The white box has the 9 volt “Wall Wart” power transformer.

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We begin by going through the parts list, making sure that nothing is missing (nothing was).

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There are two circuit boards, joined at the hip (will snap them apart later on).  Here I’ve started to add parts, resistors, capacitors, and diodes.

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The Siamese twins have been separated.  Top board is the microprocessor, bottom board is the display.  An Atmel ATtiny processor holds is the brains.  It communicates via a serial bus to the LED display driver board.  A photo resistor in the lower right hand corner of the display instructs the processor how bright to shine the LEDs depending on room brightness.

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The two boards are now connected via a ribbon cable, and the battery holder has been added.  6 AA cells can power the clock for over a week during a power outage.

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Another view of the two married circuit boards.

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The two circuit boards and the battery holder have been mounted to the bottom plate of the case.  It’s now electrically finished.

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Sideways view of the almost completed clock.

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Powered up and being tested.  The final step will be to add the wood sides and the top, then it will look just like the photo on the Heathkit Web site.   I just may buy the Heathkit 144/450 mhz antenna kit next.  Wish they would make a QRP SDR ham transceiver kit.

Heathkit Clock

Sometime in the late 1970’s or early 1980’s I built my last Heathkit, the GC-1108 digital alarm clock.  I still have it and it still works.  I did have to replace the alarm on/off switch on top with a slide switch from RatShack when the original went bad.  Now the three position set time/ set alarm/ run switch is going bad, resulting in the clock loosing the time setting when the switch is operated if I apply any inward pressure on it (carefully sliding it  is OK).

Heathkit went out of the kit business, and then disappeared after my purchase of that kit.  I’ve since purchased several already-built Heath products, including a tube tester, solid state curve tracer, and a signal generator.  Their test equipment and ham radio gear were usually designed at the perfect level of performance vs cost for the hobbyist, and being kits they gave the owner a sense of pride and accomplishment once assembled.  They were also fun to build.  Needless to say, I do miss Heathkit.

As of 2015, Heathkit is back, sort of.  I’m not sure just who the new owners of the brand name are, if there is a real, direct connection with the new Heathkit and the old, or if this is just a case of a new entity having purchased all of the IP and Logos of the former company.  They are no longer in Benton Harbor, Michigan, the new company is shipping product from Ottsville, PA, and I’ve heard that their engineering office is somewhere in California.  At the moment their website store lists only four kits, an AM Radio-Tuner (available in no solder and solder versions), an Alarm Clock, a Dual Band J-Pole type antenna for the Amateur 144/440 Mhz bands, and a SMT practice soldering kit (code practice oscillator on a ruler).  They also list a precision RF meter that seems to be stuck in pre-order hell.  I don’t know if it will EVER be available.

I hope the new Heathkit will eventually add more stuff to their catalog.  I had been eyeing their new “Most Reliable Clock” kit ever since it was announced, and I finally decided to order one and relive the Heathkit building experience again.  Unfortunately, Heathkit seems to be running hand to mouth on their inventory, building kits on order.  As a result, there is a backlog of about a month from order to shipment.  You will get an order number once you place your order, and will get an email when the kit actually ships.  Mine was sent USPS Priority Mail and shipment took three days.

So far, I’ve only opened the box and verified the contents.  I’ve just started reading though the manual.  The new Heathkit assembly manual is just as good as the old ones (maybe better).  The manual is spiral bound to lay flat open to a single page.  While there is new artwork appropriate to the current date, there are also many illustrations lifted right out of older Heathkit manuals from the 60’s-80’s.

I hope to document the build of this new clock kit and report on it here.   I don’t think they have added a 24 hour mode to the clock, which would be nice for use in the ham shack (though I intend to replace the GC-1108 on my night stand with the new one).  I got the Green LED version, that’s more pleasant to the eyes at night (same color as the GC-1108).   This is going to be fun.

Cutting the Cord

A few days ago my wife noticed that our local CBS station was missing from Direct TV. It seems that Nexstar, the troll that owns distribution rights to CBS (and other local stations) is holding AT&T up for ransom in order to get more money out of them for the right to carry the local stations. While we do have an antenna, and can bypass the satellite to receive CBS’s programming, we can no longer use the DVR feature on our Direct TV receiver. We were planning on cutting Direct TV’s cord when our contract ends sometime next year, at which time we’d get an OTA DVR. Thanks to Nexstar, I decided to get one now.

There are a few different options out there for OTA DVRs. Being a geek, I had thought of building my own MythTV box. There are several different Linux compatible TV tuners for this, with the SiliconDust HdHomeRun being the current favorite. However the Mythbuntu Linux distribution is no longer being supported, making it necessary to configure the Mythtv packages around one of the Ubuntu or Mint distros. Then I’d need to build up a micro ITX computer box to run the back end, as well as get the required tuner. An off the shelf solution wouldn’t be as versatile as MythTV, but I can always revisit the idea later.

Mention TV DVR’s and one of the first ones that comes to mind is Tivo. Tivo is a decent product, but it’s no longer the only game in town here. A quick Google search narrowed the options down to two different products, Amazon’s Recast, and Tablo. Both of these products are available in two or four tuner versions (meaning the ability to record two or four different channels at the same time). Both use a networked streaming connection to your TV, no HDMI cords. This of course, means that you need either a streaming device connected to your TV to watch the output of the DVR, or to use a ‘smart’ TV with a suitable app installed.

If you go with the Recast, you’ll need an Amazon FireTV or Fire Stick as the Recast ONLY works with Amazon branded equipment. The Tablo will connect to the FireTV / Fire Stick, but will also play with Roku streaming devices, Samsung and LG smart TV’s, Android and Apple devices, and computer web browsers.

As we have a Samsung 65” TV in one room, and a Fire Stick in another, the Tablo was the logical choice. We ordered a second Fire Stick for a third TV.

We got the Tablo Quad, which is the four tuner model. This is the latest and greatest version, which can use WiFi-AC, and has a built in SATA compartment to install the required hard disk. You can use any 2.5” hard disk (rotating or SSD) up to 8tb, but it must be 7mm or less thick to fit inside the unit. External USB hard disks can also be used (USB 2.0 or 3.0 are OK). I selected a Seagate 2tb Barracuda drive.

Setup was easy, I accessed the DVR from my Linux PC by setting my browser to my.tablotv.com to access the web app. From here I was able to scan for available channels, register the unit with Tablo, and start my 30 day free trial of their on line schedule subscription.
Yes, just like Tivo, they do charge you a monthly fee to access the schedule info (though if you’re OK with manually entering record schedules by channel, date, time, once-repeat, you can live without the subscription).   I’d have to pay for a similar subscription to schedulesdirect.org if I built a MythTV box.   Tablo does give you a discount for buying the subscription for a full year, or you can pay them $150 once and you’re good for the rest of your life.

The unit seems to work nicely. The FireTV app is rather slow, it takes about 4 minutes to start up after opening the app (including the amount of time the Fire Stick takes to boot up after tuning on the TV, selecting the HDMI port, and hitting the home button on the Fire Stick remote). But this is a version 1 Fire Stick, hopefully the new version 2 I have on order will be faster (dual core vs quad core). The Samsung TV app is much faster, it starts almost instantly, ditto for the web app on the computer. Once you select a channel to watch in the live TV section, there is a 5 to 7 second buffer delay before play starts (regardless of the device used to connect). Video quality is good, but not all of your OTA stations are in HD (mix of 480p, 720p, and 1080i). The default setting of the Tablo is 720p, but you can bump this to 1080 at the cost of eating up more disk space.

So FSCK-you Nexstar!  I wonder if I can get a reduction on my DirectTV bill by asking them to drop all of my local channels, since I don’t need them anymore to get them?

Home brew Arduino

The Arduino controller boards are easily the most popular ‘go to’ for quick and dirty microcontroller based projects.  The Arduino Uno, with the Atmel-Microchip ATMega328P processor is the most popular, costing less than $23 US for the original version, and under $10 for clones and ‘mini’ bread board friendly versions.

For projects, you’ll probably want to just build the raw processor chip into your design, but you’ll still need the Arduino setup to download your code to the chip.  This means providing the USB to Serial interface, and programming the bootstrap onto the chip.  You’ll also have to provide the required oscillator crystal and resonating capacitors.

Depending on what I’m doing, I’ll either lash up a simple breadboard to develop my projects code, or skip that step and solder up a perfboard with the minimal circuit.  An example of the former is shown below:

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The Atmega328P controller chip in a QFTP-32 package is shown soldered to a DIP adapter board.  These adapter PCB’s are available from overseas suppliers on Ebay cheaply, if you buy them in bulk you can get several for a dollar.  These boards come in several flavors as shown below:

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The ‘Quad’ styles are four sided and have single or double rows of pins.  The single row style can be used with breadboards by populating two parallel rows with bread board pins, and Arduino style sockets connectors on the other two rows.  For the ATmega328 only one such socket connector will be required as the other row only has two I/O connectors on it.  The other pins go to VCC, GND, and the crystal.  Wire fly leads can be soldered to the needed connectors and plugged into the breadboard.
The other ‘quad’ style board while not suitable for breadboard use, will more easily fit into your completed project.  This particular board is made to hold either a 32 pin style IC (ATmega328) or a 44 pin style chip (ATmega324, Atmega644, or Atmega1284).  These larger ATmegas are 3 to 6 times more expensive than the Atmega328, but if your project is memory or I/O space challenged on the smaller processor, they are a welcome option.

The dual inline style board has solder pads on the bottom for chip resistors or capacitors for bypass or pull downs.  I used them to bypass the VCC leads to ground, and to mount the crystal resonating capacitors.

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Atmel-Microchip recently introduced the ATmega328PB version of the ‘328.  This chip is only available in the QFTP and QFN style packages (both can be soldered to the adapter boards shown, but the QFN packages are a bit harder to solder, they will require the use of solder paste and a hot air soldering tool).  These parts have a few more I/O pins, and extra serial ports.

If you are using ‘bare’ AVR chips in this fashion, rather than the Arduino Uno, there are special Arduino board profiles available here.  The Minicore profile supports all of the 28/32 pin processors including the new ATmega328PB.  The MightyCore profile adds support for the 40/44 pin AVR chips, and the MegaCore profile adds support for all of the 64/100 pin variants.  There are a few other profiles available for some other less used AVR controllers.  The MegaCoreX for the Xmega parts looks interesting.

The link to the various ‘core’ profiles includes sample wiring diagrams.  There are several speed options available including the usual 16mhz, as well as 8mhz, 7.3728mhz, 14.7456mhz, 18.432mhz, 20mhz, and a few others.  The ‘oddball’ frequencies are special ones than divide down exactly to standard baud rates.  Crystals for these frequencies are quite common.  The frequencies above 16mhz are overclock rates for some of the older AVR processors (but still might work).

You’ll need some kind of programmer to flash the bootstrap onto your chip, which will require you to wire up the standard Atmel 6 pin ISP connector (see the sample wiring diagram provided with the core profiles).  For any of the AVR chips with 64K flash or less I recommend Adafruit’s USBtiny for $22.  If you want to use the larger AVR procssors with 128K or more flash, or any of the XMegas,  you’ll have to buy a programmer from Atmel-Microchip, or a suitable clone.  Another option is to use the Arduino Uno with a suitable sketch as a programmer (example on the Arduino website ).   However if you really need that much flash space, maybe you should be considering one of the ARM based Arduinos, but that’s another story.

 

 

Pic-A-Star, the saga continues

Having decided to house the transceiver in the chassis frame of an old Tektronix  model 620 CRT monitor, and to use the Pic-N-Mix DDS unit as the control processor I needed to figure out how to fit that circuit into the confines of the frame.  I had obtained a bare board from Glenn, VK3PE, which had both the Pick-n-Mix and Status board circuitry on it, but the board was too wide to fit in the available space in the chassis frame, nor could it be cut into two pieces to do so.  So I ended up using Peter’s design as re-implemented by G6AK.

The Tektronix 620 monitor was a 6″ CRT XY monitor, the one I had no longer functioned and was deemed unrepairable due to critical parts no longer being available (at a reasonable price).  The chassis frame measured about 8″ wide by 5″ high and was about 17″ deep.  It consisted of machined front and rear panel frames mounted between 4 extruded aluminum rails.  The top, bottom, and side covers slid into slots in the rails.  My unit was an OEM model, which came without the covers, feet, or handle, and was intended to be built into the OEM’s product.  I had obtained the monitor from a former employer as dumpster salvage.  As the frame is deeper than I’ll need, I plan on cutting the four rails down, probably to a depth of between 12-15″, the actual length to be determined once I’ve built all of the necessary transceiver modules and test fit them into the available space.

PanelFront.JPGAfter removing the CRT bezel and the controls from the 620 front panel, I made a new panel insert to replace the bezel, and a dress plate for the control portion of the panel.  I wanted the various jacks and the audio gain control on the left hand side, so I’m using the 620 panel mounted upside down from the way it was originally built.  I etched the two PnM boards from the artwork by G6AK, and trimmed the boards down by about 3/4″ removed from the side where the home brew optical encoder was.  I’ll be using an available encoder unit from Oak-Grigsby.   The layout is a bit different from the way G3XJP intended it, I have the keypad and status board on the lower right hand side of the display instead of to the left of it, and the encoder knob underneath the display instead of to the right of it.  I’ve combined the functions of the four VFO indicator LEDs into two by using dual color LEDs, and I’ve added a dual color LED to indicate ‘Best IP3 mode’ and ‘Attenuator on’ functions in the place of one of the VFO LEDs.  The other vacated LED position will now be the DSP LED.  I had a large 12 segment, three color bar graph LED display in the junque box, it was mounted above the display and wired to the status board in place of the called for 1.8mm LEDs.  Since this display required more drive current than the PIC could probably handle, I added a small perf board containing 12 PN2222 transistors for the extra drivers.

PanelBack.JPGHere you can see the back side placement of the parts, minus the PnM boards.

PnMdisplay.JPGThe Pic-n-Mix display board designed by G6AK

PnMmain.JPGAnd the Pic-n-Mix processor board.
I added a second LM7805 regulator on the reverse side of the board, underneath the one on top to power the DDS circuit.  In this photo the LM7808 regulator for the Butler oscillator has not yet been installed, nor has the oscillator.  (The DIP IC’s also have yet to be socketed). I plan on using an On-Semi 340mhz LVPCEL oscillator to drive the DDS.  I got this part a few years back, it looks like it isn’t made anymore by On-Semi, but there are other similar parts still available in the same 5x7mm package.

These photos show work in progress, I still need to finish wiring up the front panel boards together, and then test/debug the Pic-n-Mix.

Tools

Building your own radio equipment requires tools for soldering, and physical construction.  Everyone has their own preferences, I’ll discuss what I’m currently using.  I’ve collected quite the assortment of tools over the years, buying something new usually when the need for it arose with a new project.  Some of my tools have been in my possession for over 40 years or more now, a testament to how good things used to be made back then.

Soldering tools have changed quite a bit in the last 40 years.  Way before my time soldering irons were huge things, sometimes heated by a gas torch.  The heavy iron tip had to hold heat in to allow moving the tool from the torch stand to the work.  These things were used for soldering sheet metal, not electronics!  Smaller, electric powered versions of these ancient tools made in sizes of as much as 100 watts down to maybe 30 watts were common.  These early soldering irons took a long time to heat up, and were rather inefficient.

Then the soldering gun came along.  Rather than using a nichrome element to heat up the tip of the iron, the soldering gun had a directly heated tip made of heavy gauge copper.  It was heated by passing a low voltage, high amperage current though it, supplied by a step down transformer with a single turn secondary.  I still have the Weller Jr. 100 watt soldering gun that my father bought for himself, and then gave to me when I was in my teens.  Weller is still around today, and still makes similar soldering guns, but they’ve redesigned the clamps holding the tip to the gun.  The new clamps are cheaper to make, but the old system using heavy nuts instead of small set screws worked better.  Every time I find an old style Weller gun at a garage sale or ham flea market, I’ll buy it.

Soldering guns were fine for the point to point chassis wiring used on tube type equipment, but when printed circuit construction came along something less powerful was called for.  Lower powered soldering irons, sometimes called soldering pencils, were developed.  The latest generation having electronic temperature controls are referred to as soldering stations.  For surface mount work a hot air gun is used to heat the solder paste that is first applied to the board.  The hot air gun is required where a soldering iron cannot get to the small pads often underneath the parts.  There are two types of hot air guns, one has the variable speed blower built into the hand held tool, the other has an external air supply connected to the tool via a flexible hose.  Both kinds work equally well.   Special soldering stations, often called ‘rework stations’ combine a hot air soldering tool and a soldering pencil with separate controls for each.

I have both a Weller WES51 soldering station, and a ZENY 862D hot air rework station.  The latter is a Chinese made tool with a hot air gun (blower inside the handheld tool) and a soldering pencil.  The unit came with various sized hot air nozzles and soldering iron tips.  Both of these tools work reasonably well.

Also required are an assortment of hand tools to cut and bend wire leads, and to hold SMD parts while soldering.  I have several different wire cutters, including a flush cutter to snip excess leads close to the circuit board.  Various sizes of needle nose pliers, and tweezers, the latter for SMD work.  I also have a special cutter for #30 gauge wire wrap wire.  Wire wrapping was once a common method of wiring up a prototype circuit using special sockets with long square posts.  A wire wrap gun tightly twisted the end of a wire lead around the socket post actually making a better connection that soldering.  Parts in SMD, and dirt cheap printed circuit fabs in China have made wire wrapping go the way of the Dodo bird.  Wire wrapping wire is still made, it’s an idea gauge for bodge connections on circuit boards, for patching design mistakes in prototypes.

If you make your own circuit boards for one off projects you’ll need a way to drill out the board for through hole parts.  While they do sell drill bits made for this with standard 1/8″ shafts, I’ve found the kind usually available on Ebay from China to be quite fragile, often lasting for only a few holes.  OTOH, you can buy a set of wire drill bits #61 – #80 that will work as well, and seem to hold up.  Also  Harbor Freight  has a pack of miniature drills in sizes from 0.5mm to 3mm .   The four smallest sizes in this set will cover most through hole parts, and the larger sizes will find use as well.  At $4 it’s a bargain.

Drilling circuit boards with these tiny wire bits requires a drill press, and a high speed drill motor.  A Dremel moto tool with an adjustable chuck (instead of the standard single diameter clamp), mounted in the Dremel drill press is the ideal tool for this work.
I’ve also used a “standard” workbench drill press set on its highest speed (about 3100 rpm).  While not as fast as the Dremel  (which can get to 10000 rpm!) it does work.  Since the usual Jacob’s chuck supplied with these tools won’t clamp down on any bit less than 1/16″,  I obtained a small pin vise with a 1/4″ handle, and sawed off the end of the handle.  This is used to hold the desired drill bit (#61-#80) and is then chucked in the drill press.   The drill press in question is the Harbor Freight 8″ Central Machinery model.  It has a nice attached work light on a gooseneck mount.  I’ve replaced the supplied bulb with a screw in LED lamp.  It’s not a very powerful drill, but works well for this purpose, and for general drilling into aluminum or soft wood.
I also have Harbor Freight’s 29 piece Titanium drill set.  They work well into soft wood and metal.  As with any stuff from HF, wait till there is a good coupon sale before buying major tools. (Sign up on their website for coupons) I’ve seen the 8″ drill press for as low as $50, and the drill set for $10.

 

PC boards, Pic-A-Star

Having previously posted about building the Pic-a-Star transceiver, and making my own PC boards, I thought I’d show you a work in progress.  The two photos are of the band pass filter board.  Originally, the design used through hole capacitors and slug tuned inductors in the filters, however the Toko coils used are no longer available (except as hard to find NOS), although some builders have salvaged usable ones from old CB sets and rewound them.  I plan on using Toroids and trimmer caps, mounting these on daughter cards which will then be soldered to the BPF board instead of the Toko coils.

P1010502.JPG

This photo shows the ‘track’ side of the board with parts for the first two banks of filters mounted.  This board will perform the switching operation between filter banks, the actual filter parts to be mounted on daughter cards on the other side of this board.

P1010503.JPG

And this is the back side of the board.  Not much here; ground plane, pads where the daughter cards connect, and two bus lines for input and output.

The board was made using the process previously described using G3XJP’s artwork from the picastar project.  The ‘tin’ plating on the board is just a very thin layer of solder applied to the board with a soldering iron (paste flux rubbed on the board first).  This will help keep the copper foil from becoming tarnished.  Wish I had thought of doing that on the first boards I made!