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Author Topic: First true homebrew project  (Read 13313 times)
WA8JNM
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Posts: 175




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« on: December 28, 2013, 06:11:48 AM »

Friends,

I'm 64 years old.  Since childhood I have dreamed of constructing a true homebrew device, using only a schematic diagram with no further instruction. I'm finally ready to attempt it.  Thus far, I have only had the kit building experience.  A CW, crystal controlled transmitter, with perhaps a couple watts or more output, may be my first goal.  I hope to actually make a few contacts with it. So, I would appreciate some basic suggestions:

1. What circuit? I have almost an entire collection of QSTs at my disposal and, of course, the web.
2.  What construction technique?  Start with a breadboard (never used one)? Ugly manhattan? (Is that the right term?) Other construction method? Keep in mind I will eventually want to put the working unit in a chassis. If I start with a breadboard, do I have to redo the build to make it permanent?
3.  The parts need to be reasonably available, of course.  Where do you folks buy such parts?

Thanks in advance.

Dave
WA8JNM
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KA4POL
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« Reply #1 on: December 28, 2013, 06:43:56 AM »

You'll receive lots of suggestions for sure. One would be http://users.belgacom.net/hamradio/schemas/transmitter_1Watt_10meterband_on6mu.htm

If you go for more modern circuits you'll have less problemsgetting the parts.
I would use a perf board like the ON circuit. That can easily be put into a box. Using breadboard would mean redoing the board.
You can buy parts locally at RS or order through the web from different suppliers like Digikey, Mouser etc.

Good to see another diy guy, good luck.
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W1JKA
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Posts: 1821




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« Reply #2 on: December 28, 2013, 07:14:28 AM »

Re: WA8JNM

Parts suggestion only, haunt yard sales, flee markets, thrift stores for the $1-2 dollar older table top radios,
CB sets, stereo equipment etc. for an almost limitless cheap supply of useful parts to strip, i.e. variable capacitors, tubes/sockets, xtals, all types of filters, pots, transformers, coils, knobs, chokes, ferrite rods, filter caps, plugs/jacks etc. I have as much fun stripping old gear for parts as I do with making the HB project.
« Last Edit: December 28, 2013, 07:18:45 AM by W1JKA » Logged
WA8JNM
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Posts: 175




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« Reply #3 on: December 28, 2013, 07:59:25 AM »

Thanks for the quick responses, guys. The perf idea seems good to me, although I'm not sure what the "ON" circuit is in reference to. Thanks for that idea.

I don't think I want to use ICs; too much "already done" to meet my homebrew instinct for the first time out.

Also, I think I'll avoid 10 meters. By the time I succeed, we will probably be at the bottom of the sunspot cycle. :-)

I also want to stick to 12 volts; I figure any B+ might keep me from seeing the bottom if that sunspot cycle. :-)

Also thanks for the parts supply idea by rummaging around the thrift stores, etc. I may try that. Although, that said, what is the chance of finding the precisely correct components by that method?

I hope the ideas keep coming. I'm a real novice at this, despite the fact that the Novice ticket expired 48 years ago.

Dave

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AC5UP
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« Reply #4 on: December 28, 2013, 08:30:07 AM »

Click This:  http://redcircuits.com/

Nice assortment of audio and gadget circuits with some radio stuff mixed in. Poke around and see what catches your eye. The complexity varies and somewhere in the stack you should find a good fit for your first venture, even if it's a sequential blinky-light LED gadget. Always thought those were cool as shelf decor...........
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K8AXW
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« Reply #5 on: December 28, 2013, 08:34:58 AM »

Dave,

Books have been written supplying you the information you request!  Books!  However, I'll offer my suggestions and procedures I've used for 57 years.  I've been exactly where you are now and so I understand your questions and understand how you feel.

Let me say right off, you can be starting one of the most incredible fun journeys of your hobby career!

For a first project I suggest you narrow your search to WHAT you want to build.  Then you search past issues of QST or look in one of the ARRL Handbooks for a circuit for that item.  Then determine if it's something you think you can do.  Even after 57 years I still look at a circuit and determine "if I can do that."  

I'd stay with solid state.....transistors.  I'd avoid tubes and Integrated Circuits (ICs) if at all possible. (some refer to them as 14 legged fuses)  Definitely stay away from PICs (Programmable Integrated Circuits) because they create a whole wold of problems or procedures.

Remember the acronym, KISS.... which means, Keep It Simple Stupid.  In other words don't ruin your first "go" at homebrewing with a complex circuit.

I'd recommend using a perfboard that can be bought a Radio shack.  They have (depending on size) anywhere from dozens to hundreds of holes, each with it's own copper pad on the flip side.

Wire the circuit in the exact (or close to it) fashion as the schematic.  Left to right.  Bring the power and signal lines out to a plug in connector of your choice.... the options here are almost infinite.

If you have access to a computer you can visit the numerous vendors that sell electronic components.  My favorites are Jameco, Allelectronics, Mouser and Digi-Key.

If you don't have a computer, let someone research this for you and get them to request catalogs in your name and address.  Catalogs are great fun to explore.

Other than the perfboard, I would avoid buying many parts at Radio Shack because of their inferior quality. They will work and I do use them on occasion when I need something NOW....but prefer to buy them through one of the mentioned outlets.  Shipping charges are quite reasonable and service is fast with those that I listed.

When ordering from a vendor, always buy two of each solid state device for spares and or if you "let the smoke out of one."  It's always a good idea to build your junk box by buying spare switches, commonly used capacitors and perhaps even resistors using the same shipping charges.

Good luck.  Have fun!  If I live another 30 days, I'll be 78.  Building has been my favorite facet of ham radio for those 57 years!

Al - K8AXW


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W1JKA
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« Reply #6 on: December 28, 2013, 09:39:29 AM »

Re: WA8JNM  reply #3

Basically precise parts needed will depend on era of HB project selected. Generally harder to find and costlier parts i.e. variable capacitors, xfmrs., chassis, speakers etc., can be salvaged from older hollow state/hybrid radios. On most of my projects I only have to buy the newer type caps, diodes, transistors if called for. I tend to work backwards and pick my project/schematics based on parts on hand the same way I did as an expired novice, also 48 years ago Grin
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WB6BYU
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« Reply #7 on: December 28, 2013, 09:41:03 AM »

Here is my favorite crystal-controlled QRP transmitter - the "Pippin" by G3MY:

http://www.qsl.net/g3pto/pippin.html

It is simple, cheap, uses commonly available parts, and can be adapted to a number
of different configurations.  It can be used on any band up through about 20m or
so (as long as you have a fundamental frequency crystal for it).  The only thing that
sets the band is the output filter, and you can build those for various bands and
switch them if desired.

The critical component, of course, is the crystal.  7.040 used to be the standard QRP
calling frequency in the US, but we've been shifting down to the 7.030 European standard
over time due to QRM.  You'll probably have to order the crystal (unless you find an old
FT-243 crystal in the 6 MHz range that you want to try grinding upwards...)

The rest of the components are relatively non-critical.  The 50pf variable capacitor in series
with the crystal is for fine tuning, but you can leave that out if your crystal is close enough.
The resistors can be +/- 50% or more - it may change the current draw, efficiency or output
power somewhat, but the rig will still work.  (You might try optimizing them once you have it
running.)  The two capacitors across the crystal set the feedback level - both are common
values, but you could use 47pf and 120pf or even 100pf if needed.  (The ratio is more important
than the exact values.)  This is a point where you would want to use good quality capacitors,
such as silver mica, NP0 ceramic or polystyrene.

Just about any general-purpose NPN transistor should work in this circuit, such as the 2N3904
or 2N2222.  It doesn't dissipate much heat, so a small plastic type is adequate.  The PNP
transistor can be a 2N2905 in a TO-39 case (which makes it convenient to fit a heat shink),
though you may find that a 2N2907 in the smaller TO-18 case, or even a plastic type such
as the 2N3906, doesn't get too hot in casual operation.  (Or put several of the TO-92 plastic
types in parallel.)  Again there are lots of options, including many that are commonly available.
And cheap, so you can blow up a few in your experiments and not worry about the expense.

The stuff connected to the collector of the output transistor depends on the operating
frequency.  The capacitors C1 - C3 and the coils L1 and L2 form a low pass filter for the
desired band.  There are standard tables for these.  You can wind the coils yourself, either
on a toroid core or a toilet paper tube.  The capacitors are standard values.  You can replace
all of these (as well as the RF choke) with a parallel-tuned circuit:  I'd probably use a loaded
Q of 1 (so both L and C have 50 ohms reactance), and then the L replaces the need for the
RFC.  (You'd still want to couple the output through a series capacitor.)


How to build it?  I usually use a prototype board for experimenting, then build the circuit
itself using "ugly construction", meaning that the parts are simply soldered to each other, and
to the plain surface of copper-clad board for a ground.  Here is a good tutorial on this method
(from a site with lots of other circuits for homebrewing as well):  http://www.qrp.pops.net/ugly.asp

Here is another method, from another site with lots of interesting circuits:
http://www.intio.or.jp/jf10zl/cmc.htm

You can also cut pads into the circuit board with a file, hack saw, or Dremel tool:  the transmitter
is easily built on a board with a 3x4 grid of pads.

With something this simple, getting it working on breadboard then rebuilding it for a final version
isn't difficult.  For larger circuits I often build up each stage on a separate piece of circuit board.
For example, one receiver has a RF preamp, mixer, oscillator, audio preamp, and audio power amp
as individual pieces.  That makes it easy to try a different circuit in one of the positions.  I then
reuse the boards for other projects, because my final versions are build directly into a case of
a particular size.  If you have enough space in your case you can just mount the individual pieces
of board and connect them together.
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KA4POL
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« Reply #8 on: December 28, 2013, 10:37:29 AM »

Take a look at the Feb 1998 QST page 40. This is a 80/40m TX.
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WA8JNM
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Posts: 175




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« Reply #9 on: December 28, 2013, 11:10:52 AM »

These generous comments are extremely helpful.  Thanks so much. I'll look at the two recommended circuits right now.  Your comments are quite encouraging.

Here is one I found.  It is in the April, 2006 QST, page 28. It is a 40 meter transmitter, designed by Wes Hayward.  You think it is too difficult to start with? 

      http://www.arrl.org/files/file/Technology/tis/info/pdf/0604028.pdf

I think perhaps I'll hire a tutor, if I can find one.  Some of this seems like it would be much easier to learn by observing and asking questions, rather than by reading.  Whether there are many people that really still build from scratch, though, I'm not sure.

73,

Dave



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VK2TIL
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Posts: 344




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« Reply #10 on: December 28, 2013, 11:40:01 AM »

No RF experimenter should be without "The Bible";

http://www.amazon.com/Experimental-Methods-Design-Wes-Hayward/dp/087259923X

A wonderful combination of theory and practice.
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G4AON
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Posts: 545




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« Reply #11 on: December 28, 2013, 05:07:04 PM »

These generous comments are extremely helpful.  Thanks so much. I'll look at the two recommended circuits right now.  Your comments are quite encouraging.

Here is one I found.  It is in the April, 2006 QST, page 28. It is a 40 meter transmitter, designed by Wes Hayward.  You think it is too difficult to start with? 

      http://www.arrl.org/files/file/Technology/tis/info/pdf/0604028.pdf

I think perhaps I'll hire a tutor, if I can find one.  Some of this seems like it would be much easier to learn by observing and asking questions, rather than by reading.  Whether there are many people that really still build from scratch, though, I'm not sure.

73,

Dave

That Universal QRP transmitter works really well, I have one running on 80m.

There are some minor tweaks to the timing capacitors that are worth considering, see my "Companion Transmitter" control board, which is based on that transmitter: www.astromag.co.uk

73 Dave
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K8AXW
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« Reply #12 on: December 28, 2013, 08:37:56 PM »

Dave,

Hiring a tutor is unnecessary!  You should look around locally for an "Elmer," which is willing to help you with specific questions.  Local ham clubs and or 2M radio is a good place to find "Elmers."

While it's good to have someone show you "how to" reading is still the best method of learning.  You might have to read something several times to get it clear in your head but it's easy to read "over and over."  Whereas if you ask a question and get an answer, then to ask the same question again sometimes gets awkward. 

A good thing to get into your head is that homebrewing or learning to homebrew isn't a quick process.  It is a learning process to be enjoyed....even savored.  Learning to assemble a circuit; learning the best way to arrange components for best appearance and functionality, is the fun part of homebrewing.

Most think that using what you build is the fun part of homebrewing, but I think if you took a poll, you would find that the actual building was the fun and the usage is anti-climatic.

73

Al - K8AXW



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WA8JNM
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Posts: 175




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« Reply #13 on: December 29, 2013, 02:41:39 PM »

Thanks again for all the encouragement.

As I stated, my ultimate goal is to build some RF device purely from scratch, using only a schematic.  I have built a few kits over the years, but it didn't seem as satisfying, or as educational, as I imagined a scratch build would feel.

Yesterday, I stumbled on the book The Electronics of Radio, by David Rutledge. The book apparently talks the reader through the theory of a NorCal 40A qrp transceiver, reading it as you simultaneously undertake building that KIT. I am now considering doing this first (read the book while building the kit) so as to get a better foundation of radio theory.  In that way, I would likely be to in better shape later to build from scratch and, especially, to undertake the inevitable troubleshooting necessary from my first scratch build.

That said, I hate to delay the scratch build.  Dale (BYU), the circuit you suggested strikes me as much simpler compared than the QST circuit I mentioned in Reply 9 that I am considering as my first scratch build. I wonder if the QST article build would carry the greater satisfaction of making something that had some resulting long term functional value?  However, the one you suggested might be the ideal first scratch build project, given that it may be much easier.

Finally, thanks to Al  (K8AXW) for his online and offline support!  It's all very encouraging to a guy that has loved radio for decades, but never understood it as well as he would like.

More comments are appreciated, especially as to whether you think the Norcal/book idea is, or is not, a better first step.

Dave
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W0BTU
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WWW

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« Reply #14 on: December 29, 2013, 07:00:47 PM »

How about a receiver? One of my first homebrew projects was a one-tube 6C5/6J5 regenerative receiver (two tubes if you count the 5Y3GT).

I've always wanted to build a solid-state direct-conversion receiver. But other homebrew projects that fill a more immediate need always seem to get priority.
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