July 12, 2016
and the Small
Wonder Labs SW30+ Transceiver
Installment #4 ...
BPF, Preamp, Driver
and build-up of the classic 2-watt 30-meter superhet transceiver
designer Dave Benson K1SWL of Small Wonder Labs.
Are you keeping up with us in building your SW30+ rig?!
In this episode
we are finishing off much of the Tx chain and and getting
closer to seeing signal squirting out of this little radio!
you say you missed the last episode? You can download the podcast and
catch up on things at any time! The whiteboard material and audio
recordings for all shows are listed right there on our home page! (www.cwtd.org)
73, George N2APB and Joe N2CX
Download the Podcast
window during the show ...
- KC4VZT": http://www.mpja.com/0-18VDC-0-3-A-Variable-Benchtop-Power-Supply/productinfo/29600+PS
<20:13:25> "Pat W0BM": MPJA has always delivered on time and great
stuff. been using them for years...
<20:21:08> "Mike WA8BXN": Digispark ATTINY85 Arduino Micro perfect
to build a keyer
<20:23:06> "Joe N2CX": Gee, you get your modules this week! My
quoted delivery is 3 weeks!
<20:25:46> "Pat W0BM": I'd really be interested in seeing the
SOTABeam unit integrated with the SW30
<20:27:21> "Mike WA8BXN": amazon has the digispark boards, prime 2
day delivery, costs a bit more
<20:28:06> "Pat W0BM": The signal LED feature would be very helpful
tothis tin ear...
<20:34:14> "Wayne W6AHH": Thought we might be able to "stack" the
accessory case for more headroom in one unit.
<20:46:09> "Mike WA8BXN": 3 axis
<20:46:55> "Joe N2CX": Mike, shucks I did not see that Amazon was
selling it. I use Prime extensively. OTOH it will be some time
before I get around to using the baoards...
<20:47:41> "Obe - KC4VZT": My new HamShield a Kickstart project for
a Arduino tri band transceiver arrived but still working on it's
<20:50:52> "Mike WA8BXN": note buffer and driver are untuned
<20:56:52> "Wayne W6AHH": I emailed to try to get on of the nice
printed Elmer 101 books, but did not get response. Does anyone know
if still available or have a scan?
<21:00:19> "Pat W0BM": i'd be interested in more discussion on the
driver being untuned. It does explain why T4 is there rather than an
L something. I'm used to a load resistor in the collector for
amplifiers other than emmiter followers such as the buffer
<21:07:16> "Pat W0BM": so what is the output impeadance of the
<21:08:36> "Pat W0BM": would emrfd explain how to calculate the
<21:08:52> "Joe N2CX": EMRFD Experimental Methods for RF Design.
<21:09:30> "Joe N2CX": There is also an EMRFD email list.
<21:10:09> "Mike WA8BXN": Output Z of Q5 would be on the order of 12
V / collector current
<21:10:14> "Pat W0BM": I havethe revised first edition, any hints
where I might find info on a q5 circuit?
<21:11:47> "Obe - KC4VZT": there is also a Yahoo Group for EMRFD
<21:12:51> "Pat W0BM": Mike, the output Z for DC would make sense,
but with c 114 bypassing 51 ohms, doesn't that change the Zout?
<21:15:03> "Mike WA8BXN": I don't think so, will have more effect on
input Z. R27 gives some negative feedback
<21:15:35> "Obe - KC4VZT": That is true of even standard Digital
<21:15:49> "Pat W0BM": ok
<21:16:02> "Mike WA8BXN": C114 makes R28 not contribute to the
negative feedback for ac signals while both resistors give negative
feedback for dc bias
<21:16:15> "Joe N2CX": Yup, One can easily simulate it with PSpice
to get a good feel for the impedance levels.
<21:16:54> "Pat W0BM": so what calculates the Zout, or is that an
exercise for the student?
<21:17:25> "Joe N2CX": Zout of what?
<21:17:32> "Al - N8WQ": George can you address the GPS oscillator
<21:17:35> "Pat W0BM": Q5. sorry
<21:17:45> "Mike WA8BXN": AC variation in collector voltage/colelctor
<21:18:12> "George N2APB": Sure Al, just as soon Joe closes us down.
<21:18:18> "Al - N8WQ": thanks
<21:19:09> "Pat W0BM": thanks Joe
<21:19:46> "Obe - KC4VZT": It's been very fun with the project I've
been seeing lots of things while testing different stages to help me
learn more about RF design issues, I'm up to the last step 13 but
waiting to get some connectors to finish before completeing the
<21:20:43> "Pat W0BM": I've built through tonight, now need to test
the filter/buffer/driver. It's been a blast! Thanks for the
<21:22:09> "Mike WA8BXN": the receiver is done beofre the final
<21:22:22> "Pat W0BM": gpsdo
<21:22:47> "Joe N2CX": Thanks Mike! I'm gettting ahead of things...
(Click here if you
want to get straight to the Elmer 101 feature material farther down the
New Products of Interest to
Homebrewers & Experimenters
... Here's something that looks to be a real nice for your homebrewing
bench … a 0-30V, 3A variable power supply for $50. See pic and link
below. It’s “constant current” … you short the output and set the
current to the maximum that you want it to supply, such as in a
worst-case condition to limit current if/when you have a short-circuit
in the project you are powering. Then if there’s a fault, you can limit
the damage. NOTE: This one is a LINEAR supply, not a
switcher ... and I have this one on order!
Protective "Go Case" for radio
... Here's a *very* nice
“Multicomp” case that I used for taking to the field last weekend for
FD. It’s from MCM Electronics (http://www.mcmelectronics.com)
and about $42. High density polymer plastic, waterproof, and with
amazingly- customizable foam padding on the inside. (Link and photo
below.) Good friend Larry K3PEG loaned me his portable station for use
during FD, and he uses this case for transporting his KX3, PX3, NUE-PSK
Modem, and amplified speaker … and all the (many) interconnecting cables
for the station. The manual slides under the top foam piece, and I even
fit a 7 A-hr battery into the case as well. I was *very* please
with the case for transport and protection of it all, and will get one
myself for my own portable station: FT-817ND … unless I spring soon for
the new KX2. The Elecraft gear is just fabulous! Super intuitive user
interface and really provided me the best FD outing ever (rig-wise).
Digispark ATTINY85 Arduino Micro USB Development Board
This is a real inexpensive ($1.65) ATTINY85-on-a-USB-plug module,
that has a bunch of possible uses. A couple of us are considering
ways we could make up a display accessory for the SW30+ project.
4) SOTABEAM's new "Dual Bandwidth
Filter Modules SSB/CW" --
... I recently came across this new audio filter module offering
from SotaBeam ... and was very impressed. Priced at just $39, I placed
an order for one to try it out! It reminds me of the KK7P "DSPx"
module from way back, enabling one to adjust filter width and placement
to better hear CW and SSB signals in radios without the built-in DSP
filtering controls offered in expensive commercial radios. A
couple of us have been thinking that this would be a really dandy
accessory for the SW30 rig that we are building up in the CWTD Elmer 101
series ... what do you think?!
Nucleo-STM32 "Arduino-Compatible" Controller --
...Like many of us hams, I just love using
Arduino controllers (UNO, Nano, et al) for providing quick and
easily-modifiable code to control my projects. Well,
I've come across
this powerful and inexpensive "Nucleo-STM32"-line of modules that offers
pin-compatible use with the Arduino boards, as well as being able to be
programmed in the same manner as the Arduino software 'sketches'. So
think of this as an Arduino-on-steroids that just might be able to
handle some of the more performance-oriented tasks that we'd like to do
(e.g., DSP-like processing, filtering , faster sampling).
Amazingly there are many different modules available for order from
Mouser, ranging from $10-$23. I have one of each (pictured below)
on order for experimentation ... and maybe we'll see the Nucleo in
future CWTD project? ;-)
6) AA0ZZ Blank Enclosure Kit from
Craig Johnson --
(soon to be available for order) ... This is the same nifty red pcb
"enclosure kit" as Craig offered for the SW30+ project, except there are
no holes and no silkscreened labels! Perfect for adding your
accessories (e.g., keyer, display, audio filter, amp, speaker, Arduino
controller, et al) into a color-coordinated, same-size enclosure that
looks terrific side-by-side with your main SW30 rig. Craig tells
us that this new offering will be about the same price as the SW-30
version (~$18) and will be available for order in about 2 weeks.
Yay, and thanks Craig!
CWTD Episode #81:
Elmer 101 and the SW30+ Transceiver
Tx BPF, Preamp & Driver
First, a few Notes:
Kits are sold out.
SW30-specific Enclosures are sold out ... but see
the Big Surprise listed above in the New Products section: BLANK
ACCESSORY ENCLOSURE KIT from AA0ZZ.
Bare SW30 pc boards are sold out.
You can get the FreqMite Kits now from 4SQRP ...
http://www.4sqrp.com/freq-mite.php ... And AA0ZZ shows
how to connect it to your SW30.
Accessories in progress ... Keyer Kit, Display,
Arduino control, Spectrum output
For the latest & greatest SW30+ Kit information,
see/download the Updated Manual