Ham Fest

I got up at 4:45AM today, to ready,  travel, and attend the Annual Mike and Key Ham Fest at Puyallup, near Seattle.

I just returned - it was great!

There was more stuff than could be viewed. The crowd was large, but we managed to get around to all of the tables.

Several of the local pQRP club members were seen, on one side of the tables or the other.

My purchased treasures include;

• four each 90deg BNC connectors, 
• six each 1/8th inch shaft knobs (for a audio adapter circuit that I am building),
• and, an order for a new MFJ 269 from HamRadio.com, at a very nice discounted show-price, with free shipping to my home.

I am normally a sucker for Large Variable Capacitors, but some how I managed to avoided temptation.

We watched one fellow buy a milk crate full of some very nice Variables for only $20.00

Many older Mike and Keys were available, the D104 was well represented.

 -

The Show Queen was sitting on its own old original box.

It was a great day, now we just have to wait 354 more days for the next event.

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Signal Generation

I have been watching Jeff's - KO7M Blog and his current QRSS/WSPR Transmitter project using the DDS-60 as part of the prototype. Jeff had previously done some work with the AD5330 8 bit DAC.

Jeff's efforts have inspired me to look at a previous purchased Si750 SDR-Kit, that I still had not built.

Without much difficulty, I now have put the Si570 SDR-Kit together (only the 3.3v Regulator went in backwards, which I fixed). Testing is still in progress.

While investigating; the kit's circuit and the Si570 datasheet, the DDS-60 and its AD9851 device, I have learned a lot more about micro-controlled frequency generators and DDS's in general.

This may be Old Stuff for some folks, but this is what I have learned, this info is saved here for my future use:

The Si570

The Si750 SDR-Kit is a real neat device with a very wide frequency range of 10MHz to >900MHz and can be controlled via a two wire computer connection (I²C). It's output is square-wave, which is ideal for a mixer LO of a receiver

But, the Si570 has some limitations for use as a general use signal source. The output (square-wave) would require difficult frequency sensitive filtering to obtain a clean sine wave over the entire frequency range.

Obviously for a single frequency, a filter can be easily created, but for that single frequency, a simpler crystal or oscillator circuit could be used instead. 

Once setup, the Si570 output is continuious, without assistance from the computer or micro controller. 

The DDS-60 

More information needed.

The AD5330 

The AD5330 8 bit DAC is a general purpose signal/wave-form source with a frequency range of 1kHz to 36kHz. It uses DDS processor to create the output wave form. Almost any shape of output can be created.

For use as a AF signal source, it's output is normally a stepped waveform, which normally needs a low pass filter to remove the steps.The output can be used with a mixer to create double sideband signals. 

A continuous use computer or micro controller is needed to generate the steps of the intended frequency or wave form.

I need to explore these circuits more, and will update as necessary.

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New Headset

I have been needing a new Computer Headset for a long time. My old set was getting tired and recently one of the plastic brackets/bands broke and was unusable. I had been looking for a replacement for a long time, but could not find anything that I liked.

Must locally available Headsets (in stores) are of the "pad on the ear" type, for radio work and Echolink, I wanted "around the ear" cup type for better noise rejection. Web searches found several, but they seemed expensive and lacked the personal recommendation that I was looking for.

I requested recommendations on the Sunday Night Echolink "QRP" QSO, someone suggested the following:

SONCM
Stereo Dynamic Headphones
SM-750M.V
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=170466481487

The Headset looked good on the web page and the price was right (only $6.38 with free shipping), but at that low price how could they be of any good?

But, for only six dollars and change, how can I go wrong, my order was placed that night.

I received the Headset on Friday, and have been using the new Headset since. They feel good, sounds good, and are light on my ears and head. The new Headset has an inline volume control, which is nice, as my old set lacked the local control. The slight angle of the ear cups (with respect to the band) and the limited mic boom rotation angle, requires the mic to be located on the left side only. My old headset allowed the mic on either side. I previously used the mic on the right side, I will have to get use to the mic on the left side only.

The Headset is mostly plastic, but if they hold together, I think they will be a good valued addition to my shack.

I talked with John - KB0ADD, he also placed a set on order, it will be interesting to hear his evaluation report.

To the person on EchoLink QRP that suggested this Headset - Thanks.

Interesting: I see the Headset has increased in price, they are now $7.09

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UPDATE
I have now been using this Headset for a couple of weeks, I like them and found the inline volume control very useful. The cord is about 18 inches shorter than my previous set, but still very usable. I purchased two additional sets, one for each of my other workstation locations.

A very good value!

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More PCB Work

Practice has not made perfect, yet.

I thought the new found targets for DipTrace PCB was going help me do the Double Sided Alignment trick, see previous post. The concentric circles looked good on paper, but in practice they are too thin to stick to the PCB for Toner Transfer. The solution is simple make the circles lines thicker - ah, no-can-do with DipTrace. The targets were made from software built-in "Mounting Hole" art (for reasons given before) and the image thickness for circles can not be altered. Too bad, it was a good idea. Other software PCB packages may have more flexibility for creating Targets.

So, back to the drawing board.

I created PAD art for a target. Pads and holes are the only items that DipTrace prints on all layers (Component and Circuit Side of the PCB). My new Target (pad) is 500 mils dia, with a hole 475 mils, which creates a nice circle with a line thickness of about 12 mils. This photos shows the results after Toner Transfer and Etch.


A major part of the lower center Target (circle) was lost in the process. The rest of the circuit looks great.

Now, for the new (maybe hard) part, aligning the second side art with the the first. The Transfer Paper is shown behind the PCB material with the Targets (circles) in alignment. So far, everything has worked as I expected or hoped. Note: the shiny surface on the PCB is clear tape, used to avoid addition etching while the second side is being etched. I inadvertently cut the Transfer paper too short, note the missing targets on the right side, with multiple redundant targets recovery was easy.

The second side did not Transfer or turn out a well as the first, some of the Toner came off in the water soak process. I think when I changed the water in the bath, the water was TOO hot, which "shocked" the PCB material and it expanded faster than of the paper (or vise versa).

A little of the Board Outline Trace and most of the Targets came off the PCB (maybe popped off) near one end of the image. Other than that, the alignment as inspected on the light table looks very good, as shown by light through the center of the pads and VIAs (click on the next image for a good look).

Note: the 60Hz hum bars on the photo were created by the flickering florescent lights of the light Table.

Good alignment can be check by inspecting the small 10 mil holes in the VIAs, five VIAs can be found on the board.

I will not use this PCB to build a project, it will be kept as an example. Due to some of my experimental last minute PCB design edits, the holes on the major PADs had reverted to the default size (35 mils), which is too large for my project (I actually wanted 12 mils holes). I will have to re-make the board.

My next experiment will include more attention to the thermal environment of all processes.

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Targets for PCBs

It is amazing, how simple ideas can make a world of difference.

As stated in the previous post, adding Targets to the edge of PCB Layout Art will allow me to accurately align both sides of the PCB images for the Toner Transfer Method of building double sided boards.

Use of targets is not new, but my use of them with Toner Transfer is new to me.

I have struggled with image alignment while building double sided boards in the past, Toner Transfer make the task much more difficult compared to Optic Film Exposer Methods. With the optic film method it is easy to see through the art work for alignment and both images can be taped together and/or exposed together in a double side exposer fixture.

I have search the web for ideas regarding Double Side Toner Transfer methods and found nothing that I liked. Some suggest holes and pins to provide alignment, but transferring the resulting sandwich for lamination is problematic.

The Toner Transfer process normally uses non-transparent transfer paper, and therefore alignment of the two images is difficult. But, alignment can be done by adding target around the layout image (similarly as done with optical method) and partly extending them beyond the edge of the intended PCB material.

The etch process becomes a two step process, one for each side. The first etch creates the first side of the intended PCB layout pattern and copper targets that extend beyond the edge of the board. The etched targets on the edge of the board are aligned with the second side target images that extend beyond the edge of the PCB material.  Both target sets are created from the same computer art work.

Circles are used for targets, as your eye is much more sensitive, to slight phase shift (or displacement) of concentric overlapping circles, than as can be seen with just straight lines.

With DipTrace (the PCB software that I use), targets can be created using Mounting Hole images, multiple holes are stacked one on another, and then saved as a library part.

What this means to me

My abilitiy to build much more complex Homebrew PCB has greatly improved.

I have now experimentally used this method to build a PCB with 8 mil traces, 12 mil clearance, and 40 mil "VIA's" pads with 8 mil (or maybe smaller) holes. Solder and tight fitting clipped wires will be used in the VIA's  to provide double sided connectivity.

Note: This is a great tip that I found on the Web; use a single long wire, stitched between all VIA's with loops between, solder the wire at the VIAs and then clip the loops away.

I have found installing (looping) VIAs after all other parts to be helpful, it avoids adjacent part installation dislodging the very sort clipped wire that form the VIA.

Component Side Targets                Circuit Side Targets

The targets are randomly placed around the Layout, the odd number of targets and placement help avoids confusion when attempting alignment. In theory, only two targets are needed, but more targets ensure enough are properly etched and are usable in practice.

For use with PCB Toner Transfer Method, the Component Side image is must be Mirrored via the laser print process.

The example shown here are very small boards (1x2 inch), alignment for larger boards with larger traces should be even easier.

It is interesting, once a long time ago, I was involved with the production of Technical Manuals and their Art Layup, many of the techniques that I used almost 40 years ago find their way into my projects of today.

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HB Two Sided PCB

Up to this point I have always created single sided PCB using the Toner Transfer Method. I go to a lot of effort to arrange parts to avoid the need for Double Sided Boards. For more complex circuits that is difficult without circuit jumpers.

It is difficult to produce Double Sided PCBs, the lack of the ability to see through the PCB material makes it is difficult to line up the second side art work with precession. Yes, it can be done using pins and holes, but I don't like the idea.

It occurred to me that if the PCB material was exactly the right size, alignment may be possible, but alas, my attempts have failed to provide the precession that I need. I do not like to have to try to cut the PCB material with that high level of precession, and Toner Transfer does not work well near the edge of the PCB material.

Then an Idea!

If common artwork extended beyond the edge of the PCB blank, it could be used for alignment of the second side art, without the need of seeing the pads through the PCB material.

So, now to try it.

I added large makeshift (or crude) Targets around the proposed artwork. As it turns out DipTrace (the PCB software that I use) does not have a Target symbol and all normal "Assembly" art includes component symbol information that over prints onto the PCB circuit layout.

So for my first attempt, I created several large PADs (250 mils) with a large holes (245 mils) and placed them around the PCB, because the pads over print each other the results looks like a clover leaf, shown at each corner of both sides of the layout. Note: this is a small board that is 1 inch wide and 2 inches long. Traces are 8 mils, with 12 mill clearance, the front side ground grid is 8 mils on 24 mil centers.

Side One and Side Two Art

Makeshift Targets

The PCB material was cut small enough to not obscure all of the Targets but yet large enough to cover the circuit.

Ready for Lamination

The results are not perfect but usable, the targets did not transfer as well as expected, this is a normal problem near the edge of the PCB material.

The alignment targets are easily usable

for alignment of the second side layout

After the first side has been etched (while the back side was covered with tape), the Targets are used to align the second side art before lamination. If not careful, the lamination process can sometimes slightly shift the art.

Sorry, I did not take photos of the second side alignment process, here are the results after drilling holes while holding a Dremel Tool by hand (I really need to build/buy a hole drilling jig). If you look close (click to zoom in), the errors are my lack of ability to drill accurate holes by hand, and not the art work alignment problem. There a few holes (example, upper center) with good alignment on both sides.

The second side did not print as well as expected, but I am sure that is because I did not wash or clean the second side after removing the tape used as a mask for the first etch.

The smallest of the PCB holes are "via's" which are a 40 mil pad with a 10 mil hole.

After this first experiment, Gerard Yvraut (a fellow DipTrace user) pointed out "Mounting Hole" art prints on all layers as hole art - Just the thing that is needed to make this process easier.

My next attempt will be better.

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Another PCB in the Bag

John - KB0ADD, is planning to build an IOIO Antenna and wanted me to build the PCB for the Duplexer. The "KI0AG Micro-Duplexer" design is documented by K0LEE on his web site at: http://k0lee.com/duplexer.htm. John and I chat often about his projects on Google Chat, and on the Sunday Evening EchoLink "QRP" conference call.

It is a cold bright winter day in the Pacific Northwest, just the kind of day for an indoor shop project.

Winter in the Pacific Northwest - Near Seattle

About 30 Deg F

For this project, I used the "Toner Transfer Paper" and GBC Laminator from Pulsar, , and the following "Etch In a Bag" method to produce the PCB, it is fast and easy.

Etch In a Bag

I use a little Ferric Chloride in a Zip Lock Bag, warmed under hot running water - it took about 6 minutes (dependant on the freshness of the etch) for this 1/2 oz copper clad board. Running Hot water over the Bag while etching provides gentle agitation of the etch. A small air pocket within the bag assist in etch movement.

Ready to go to the sink and running hot water
Trouble spots can be helped by rubbing them
through the bag with your fingers
Photo taken at 12:26:49

A Quick Look - Finished and ready for Clean Up

Photo taken at 12:32:21

A Flawless Print/Etch, Ready for Resist Removal

Photo taken after Clean Up and Inspection at 12:39:24

I did not use the suggested "Green Foil" (see Fab-in-A-Box) to cover the Toner, as the laser print was very dark and full, the result was much-much better than I expected.

Clean Up

Normally I store the Bag with Etch within yet another Zip Lock Bag hanging via a clip for later use. Storing the bag vertical prevents the etch from invading the bag zipper.

The Bags that I use are brand name "Ziploc" Heavy Duty Freeze Bags.

I will use Scotch Brite and warm running water to remove the Resist, it is easy and not a chemical mess.

Note: this batch of Ferric Chloride is about spent. The next project will go into a fresh bag and etch.

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UPDATE

I did not start with fresh the Etch for the next project (see next post), I was lazy. This old stuff etched a bit slower, but it worked OK with the aid of heat from running hot water over the bag.

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QRSS Beacon

Initial QRSS Project Success

My QRSS Beacon Project is a success (see previous post), it is transmitting FSK on 30m with about 43uW. The onboard K1EL Keyer still needs to be programmed with a Standard Messages, and put into the real Beacon mode - but that will come later. The Keyer works now to send interactive FSK.

QRSS 30m Beacon

The thing that this project adds to my "Family of Marker and Beacons", is message programmability and interactive FSK demo use.

The following capture is from my local QRSS Grabber, the "SEA" message was shorter than my call and was easier to setup for this initial test. SEA is designator for the Seattle Airport. Note: for QRSS each "dit" is sent for 3 seconds - as shown this three letter message is about 50 seconds - but very-very low bandwidth.

The initial Short Term Stability,

and Frequency Shift - Looks Acceptable

The completed demonstration station, with a Key, is as follows. In normal use, the transmitter alone will occupy the inside of a tube, which is used as the center insulator of a 30m Dipole. See the results of my previous experiment.

A 30m FSK Transmitter

The silly (very short) vertical antenna (seen in the close up) provides some coupling and load for demonstrations.

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More on Fading Labels

Fading Part Bag Labels is a real problem that should NOT exist in this High Tech Information Age, see previous post. Some SMD parts do not have individual nomenclature and are almost worthless when the bag label fades.

I placed an "Open Letter to Mouser" on the Homebrew_PCBs Yahoo Group List, and have received a lot of list user responses. I hated to place the Off Topic letter on the list, but I did not know of another place where so many effected people share.

Maybe, we can get some help with this problem. 

I have updated my previous post with additional information and a few proposed solutions.

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QRSS Beacon Progress

I have installed the few K1EL Keyer required componenets on the QRSS Beacon Project (see previous post). With so few parts I did not expect any problems, but it is nice to see something working.

http://www.youtube.com/watch?v=Adcfd3B22aU

That was easy, this is the first video that I have posted via YouTube, it was recorded via my HTC Droid Cell Phone - it was easy enough, maybe more will follow.

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