This is the effort of two retired guys, John Fisher K5JHF and I, (and other AQRP members) to make some useful kits available for you at reasonable prices to encourage kit building and homebrewing. As you can quickly determine, these kits are all based around readily available, low cost Microcontrollers with flash (program) memory and most use a certain LCD display that was very, very, inexpensive. The criteria for us, as "low buck" designers, was that firmware development tools have to be free, hardware interface tools have to be inexpensive, and PC board design tools have to be free.

As we run out of parts we'll just order more if there is interest in the kit. Some kits may be retired as the number of kits grow or demand falls off. Should be fun and educational and that's what this is all about. I'll make improvements to the web site as time allows and hope to make it convenient to use. Both John and I are ready to answer any questions and help out.

I just got back from the post office and the rates went up Jan 27th, 2013, especially for DX, so I had to adjust the postage charged.

I realize there are some Hams out there who think they will have difficulty with the small surface mount parts placement and soldering and "think" they can't do it. I highly encourage you to try. If you "ping" a small part across the room and it's lost forever, contact me and I'll send you another at no cost. Some may have vision problems, steadiness problems, etc, again I encourage you to try.



To order kits please contact me directly at K5BCQ followed by an @ sign followed by ARRL.net with no spaces. Or via mail (OK in QRZ).

There have been some problems with the email forwarding through the ARRL Website so let me try this as an alternative; hopefully to also cut down on the robospam. You can also contact me through windy10605 followed by an @ sign followed by Juno.com with no spaces. Let me also do the same for the other email IDs.



The Hi/Lo Temperature Kit #1

Back for another 30 Kit Run

An assembled Hi/Lo Temperature Kit #1.

Closeup of the small microcontroller board with the temperature sensor (8 pin SOIC). The microcontroller is on the back of the board.

This is one of the easier to build kits. It simultaneously shows the Low, Actual, and High Temperature readings in degrees F or degrees C (so it's educational too). You reset it by momentarily turning the power OFF and back ON. The default is degrees F. If you want it to read in degrees C, short out jumper "J1" on the small board. The battery consists of 2-AA Alkaline cells and should last about one year. Use Alkaline cells because of the 1.5V rating. Rechargeable NiCad cells at 1.2V are really too low for proper LCD contrast. The temperature sensor is a MicroChip MCP9801 which is spec'ed at +/-1 degree C from -10C to +85C and +/-3 degrees C from -55C to +125C.

So what comes in today's Hi/Lo Temperature kit ? .....Bill of Material:

The price for of this Kit is $10 plus $3 postage in the USA and $9.50 postage for DX.


The Si570 Controller and Frequency Generator Kit #2

An assembled Si570 Controller. The LCD shows Memory location "36" and 14.060Mhz with the cursor in the 1Khz position.

You can see the Si570 chip soldered on the back.

New V4.x board with 4 mounting holes and a more convenient way to interface the I2C Bus to an externally mounted Si570.

This standalone unit (no attached PC required) has a frequency range of 3.5Mhz to 1417.5Mhz (yes, 1.4Ghz) depending on the Si570 part used. I have tested it up to 1200Mhz which is as high as my scope will go. Really an amazing, low jitter, and very low spur levels chip. You can go to the SiLabs website and look at the specifications. All setup and control is via the rotary encoder knob and it's push button. Power is battery (3V) or external power (5V-12V). It's compatible with all Si570 CMOS and LVDS versions, single ended or differential output, and any default frequency. This makes an ideal signal source for SoftRocks and many other projects. The Si570 Controller and Frequency Generator Kit includes a 12 digit LCD frequency display, a programmed MC9S08QG8 microcontroller, and a rotary encoder for tuning. It can ordered with a CMOS Si570 chip which is spec’d at 3.5Mhz to 160Mhz. Using other LVDS Si570 parts, the frequency range can be extended up to 1.417Ghz.

NOTE: I have received a few emails from people who accidentally applied reverse voltage to the 12VDC input and took out some parts. To prevent this from causing damage, in the future, I am adding a silicon diode to the kit .....to be mounted in series with the 56 ohm resistor (R1). If you think you might accidentally reverse power sometime on an existing unit, and who doesn't, I would suggest adding a diode to your Si570 Controller.

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ERATTA for V4.x Boards

Looks like SiLabs has changed the programming spec and disabled some math multipliers to facilitate their implementation of "Speed Grade". "A" Grade (1.4GHz) parts are not affected. I don't know how "B" parts are affected by the present Si570 Controller code. We use the "C" grade CMOS (160MHz) and LVDS (280MHz) parts. Using the existing Si570 Controller code does not appear to affect CMOS "C" level part operation, but the LVDS "C" level part is now limited to 260MHz with the existing Si570 Controller code (4 programming dots).

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Jack Smith, K8ZOA, of Clifton Laboratories has provided an excellent evaluation of the CMOS Si570 capabilities and the Si570 Controller kit at Clifton Laboratories

Sid Boyce, G3VBV, provided additional insite on how he used his Si570 Controller at G3VBV info

Features:

The display is a 12x1 serial LCD (3-3/4" x 7/8") and the programmed microcontroller is a Freescale MC9S08QG8. All the parts are supplied (except the batteries) and an instruction sheet is provided.

There are many output options available ranging from normal termination resistors to isolation transformers to LVDS/ LVTTL level converters. Some of thse devices have their own frequency limitations such as the MiniCircuits RF transformers are spec'ed to 800Mhz and the FIN1002 is spec'ed to 400Mhz. It's totally dependent on your application. The Si570 Controller board has footprint options for many alternatives. Also some of you bought Si570 parts from Tom Hoflich, KM5H, and may want to use those parts. Some of you have sample parts or parts from other sources. For that reason, the kit is offered with or without the Si570 part. The Si570 parts I supply are CMOS "C" speed which means they are spec'ed 3.5Mhz to 160Mhz by SiLabs (although they have been observed much faster than that).

So what comes in today's Si570 Controller kit ? ......Bill of Material:

The price for of this Kit without Si570 is $25 plus $4 postage in the USA and $12.75 postage for DX.

The price for of this Kit with CMOS Si570 (160MHz) is $40 plus $4 postage in the USA and $12.75 postage for DX.

The price for of this Kit with LVDS Si570 (260MHz...see Eratta above) is $45 plus $4 postage in the USA and $12.75 postage for DX.

Options:

There are 2 optional parts available. None of thse are required for an operational kit, only if you want complete DC isolation or LVDS conversion from differential to single ended LVTTL.

Mini Circuits TC1-1TG2+ (easier to solder than the previous TC1-1T+) RF Transformer is $2 plus $2 postage in the USA and $2 postage for DX. No postage if ordered with a kit. You only need this part if you want complete DC isolation.

FIN-1002 LVDS to LVTTL Converter $1 plus $1 postage in the USA and $2 postage for DX. No postage if ordered with a kit. You only need this part if you are using a LVDS Si570 and you want to have an LVTTL single ended output vs the differential LVDS output.


The Morse Code Buddy Kit #4

A MCB with keyboard, headphones, and a set of homebrew Iambic paddles made from two sections of hacksaw blade. Those blades are hard to drill but have the right spring feel.

Closeup of the MCB. The large pads (on both sides of the keyboard connector) are for attaching two spring contacts which, when grounded to the keyboard connector shield become a small iambic paddle. Neat, huh ?

More detail on soldering relay contacts as a cheap iambic paddle ....sorta.

This is the MCB-II. The Beeper and Microcontroller locations are switched, making it much easier to change out the microcontroller for different functions.

The Morse Code Buddy (MCB) allows you to receive and send practice code at speeds of 3-wpm to 40-wpm with a keyboard or iambic paddles, or just shirt pocket use for receiving practice code via the beeper or headphones. For those in the know .....and real CW operators, this is a Type B iambic keyer. There are three versions of the microcontroller, which is pluggable. The "C" version sends random 1x1, 1x2, 1x3, 2x1, 2x2, 2x3 calls (USA and DX) with 20 varying tones on a per call basis (sorry, no random noise in the background). It will send all alphabetic combinations. The "P" version sends random groups of all Morse Code letters, numbers, and characters. The "B" version will allow Beacon mode where one character string you define is repeated at an interval you define. Handy for calling CQ on a basically dead band or use during transmitter hunts. Hit any keyboard key on any of the versions and it reverts to iambic keyer mode.

It's also a 512 byte memory keyer, with adjustable tone, keyboard or iambic paddle input, Tx keying via a 2N7000, and it's powered by 3-AA Alkaline batteries (>100hrs). Do not use rechargeable NiCads. It's not required from a power standpoint and the 3.6V voltage is too low. The two large pads to the side of the keyboard connector can be used for isolated mounting or fabricate a set of paddles from the pads to the grounded shield of the keyboard connector (old relay contacts ?) and you have yourself a set of homebrew mini-paddles. Cool, huh ? ....check out the picture above.

The power options are many since the power requirement is 4-5VDC. You can use the battery box provided with 3-AA Alkaline batteries for portability, you can tap 5V off your rig if that is available, you can use an external 5V power supply, or you can tap 5V off a computer USB port you may have on the desk (all you need is a cable with the USB connector). If you use a cable for power it's a good idea to provide a strain relief using a plastic tie-wrap through one of the two holes at the keyboard connector end of the board.

This is a relatively easy kit to build. Some of the parts are an interference (tight) fit so they stay in place when you flip the board over for soldering.

Features:

So what comes in today's MCB kit ? .....Bill of Material:

The price for of this Kit is $15 plus $4 postage in the USA and $9.50 postage for DX.

Each kit is supplied with a "C","B", or "P" microcontroller (you specify). If you want more than one, please add $5 for each additional microcontroller to the above numbers.


The Digital QRP mWattmeter II Kit #9

K5BCQ's mWattmeter II packaging scheme using a "Royal Crown" LMB #CR-531 box. The tactile pushbuttons (Up, Down, Mode) which come with the kit (you can use both Up and Down pushbuttons or only one of them) are mounted on the bottom of the ADC/Microcontroller board in this enclosure scheme and protrude far enough to be used from the front of the enclosure if you bevel the hole edges a little. The bezel and On/Off toggle switch are not included in the kit. I call this "flounder packaging" ....due to this enclosure's aspect ratio and the LCD on top ;o)

Inside of the LMB #CR-531 box. The AAA bias battery can be mounted on either side to suit your enclosure. Here it is on the bottom of the Directional Coupler board. The Berg connectors were added on my unit because it was removed often during development.

Top view. Mount T1 on the top of the coupler board and T2 on the bottom of the coupler board using a small piece of double sided tape as a spacer off the board. This locates the board between the two transformers for isolation. It also puts a spacer between the toroid coils and the ground plane to reduce capacitive coupling. The single turn of wire is a short piece of RG-188A/U coax (just like RG-174A/U but it's Teflon so much more "solder iron friendly") and ground (ONLY) one end of the shield to a nearby ground via on the board. This provides a Faraday shield between the primary and secondary of the transformers to reduce capacitive coupling between the windings.

I cut slits in the coax jacket to make it more flexible. Any derbis comes from a "helpful" cat (Inspector #2) who insisted on checking all the solder joints and as you can see, it's very stressful and tiring work.

This shows the bottom of the coupler board. I cut slits in the coax jacket to make it more flexible.

Thanks to John Fisher, K5JHF, and Milt Cram, W8NUE, for the microcode and Ben Bibb, NO5K, for taking one heck of a lot of data in his lab. Power measurements have been surprisingly accurate from 160m to 6m at better than 3% in the QRP <5W range which was the focus of this design. I was talked into raising the power to 20W at a later time. Thirty-three curve fitting polynomials are used, three per band, 11 bands. All thirty-three are second order. Eleven band selections, between 6m and 160m, are used to further improve accuracy by not having to "average" any data readings.

This particular project has provided me with considerable education. In order to maintain good accuracy (<3%) at the low end (the design point) I've found out that the data is only as good as the test equipment used to obtain the curves. The math is straight forward, the hardware is not. First, it's much easier to make an accurate mWattmeter using my design point than it is to make an accurate INLINE mWattmeter, or even more so, an accurate INLINE mWattmeter which shows VSWR. Directional Couplers with toroids are not known for stablity/ accuracy and a separate enclosure with better RF bypassing of the analog voltage would help some, but ferrite material is inherently affected by temperature (power) and RF coupling between the two transformers. Second, there are Amp output impedances to consider, LPF characteristics, Attenuator characteristics, etc, etc. There is a considerable difference between "ham quality" and "commercial quality" instrumentation. This is my best run with available instrumentation.......most of it lab quality, callibrated, and excellent, some of it, like the LPF, "ham quality". At a later date, if someone can provide me with better ADC voltage to power data, it's relatively easy to update the microcode via the BDM socket on the board and/or the kit is now supplied with a 16 pin DIP socket for the microcontroller.

IMPORTANT: The mWattmeter V2.0 microcode will only produce correct readings with the Directional Coupler wired as described and shown above. The earlier V1.0 microcode compensated for unwanted coupling between the toroids and is no longer required. The mWattmeter II is designed for 50 ohm impedance input and 50 ohm impedance output. Variations from that will effect data accuracy. When measuring the output from a Power Amplifier be sure and use a good 50 ohm LPF, otherwise the additional output frequency harmonics will distort the observed readings.

There are six LCD display Modes; #1) shows raw Forward/Reverse voltage being sent to the ADC by the Directional Coupler board in 0.1mV increments. #2) shows the battery Voltage as x.xV, #3) shows "BBBFxx.xxxsY.Y" where BBB is the Band from 6 to 160, "F" indicates Forward Power, xx.xxx is the Wattage in 1mW increments, s is a space, and Y.Y is the VSWR from 1.0 to 9.8. #4) shows "BBBFxx.xx*x.xx" for the higher power levels and is in 10mW increments, * is a backwards "F" for Reverse "Forward" Power, x.xx is the Reverse Power in 10mW increments. #5) shows "BBBFx.xxx*.xxx" for the lower power levels and is in 1mW increments, * is the backwards "F" for Reverse Power, .xxx is the Reverse Power in 1mW increments. #6) provides some additional detail on the bands covered .....the bytes were free, what the heck.

Use Alkaline cells because of the 1.5V rating. Rechargeable NiCad cells at 1.2V are really too low for proper LCD contrast. Power consumption is about 1.25mA......not much.

The mWattmeter uses a (very familiar) 12x1 digital readout, will measure 0.25mW (actually a little lower) to 20W (that's about a 50dB dynamic range), has automatic range switching of 3 ranges (0 to 45mV, 45mV to 450mV, and 450mV to 2.0V), uses a total of 33 polynomials for curve fitting, uses matched Schottky diodes which are forward biased at 5uA, uses an 18bit differential input ADC (vs the usual 10bit or 12bit ADC), that allows temperature compensation by utilizing the differential ADC inputs, Battery operation (2-AA Alkaline, 1-AAA Alkaline for bias), draws 1.25mA so batteries should last even if it's accidentally left on, has a battery voltage indication, will store selections automatically and power up in the last state used, has a 6-pin BDM connector for reprogramming with a USB Multilink or USB Spyder, and provides 2 BNC connectors.

Most of the recent low power wattmeters have used log-amps like the AD8307, AD8310, LT5537, etc. (and there are many more, largely driven by the cell phone and RF tag industry). In addition to the obvious log curve linearization, one key advantage of the log-amps over diode detection is that they provide range "compression" resulting in a very wide dynamic range (80dBm to 100dBm). The main drawbacks are cost (in my opinion), unuseable packaging (ever hand solder an 8 pin CSP ?), and we don't really need that much dynamic range (maybe 45dBm to 50dBm).

After considerable diode specification searching (special thanks to the Crystal Radio group for some really great links), I came to the conclusion that there are basically two alternatives left for a non log-amp wattmeter, 1) use a good pair of matched germanium diodes or 2) use a good Schottky diode pair and forward bias them slightly (5uA is good). After purchasing some germanium diodes (1N60, 1N34A, 1N270, 1N277) and testing them for stability and consistency it was determined that germanium diodes have neither. The "best" germanium diodes out of this batch were those labeled "ITT 1N277". The 1N270 diodes marked "1N270" or with color bands were very good also. 1N34A diode quality (several batches) depended heavily on the supplier. Some were really bad (forward resistance varied 5x+), some were "just so-so". I was really looking for low end accuracy and settled on the HP HSMS-2815, a matched pair of low barrier Schottky diodes. The matched pair comes in handy for balancing the bias levels into the differential ADC inputs and offers temperature compensation using the ADC differential inputs.

The next step was to decide on the directional coupler values based on our constraints of <1mW to 20W and max input to the ADC of 2V. I don't want to use resistor voltage dividers with their inherent tolerance variations. The fewer the components in the bridge frontend, the better. Using 20W as max and 2V as max, we need a coupling factor of about 1:200 or greater. Since the transformers give us a 1/(N*N) coupling factor, N must be 16 or more turns (1:256). From the ARRL Antenna Handbook.. The low frequency limit of the directional coupler is determined by the inductive reactance of the transformer secondary windings. The inductive reactance should be greater than 3x line characteristic impedance to reduce loss at the lower frequencies where the circulating current will be significant. The result is heat which we don't want. For 50 ohm line that is 150 ohms and that works out to be 13uH for 1.8MHz. That is why so many designs using small powdered iron cores "cook" them at the lower frequencies. A material #2 (red) T-68 or T-80 core with 30 turns, only has an inductance of about 5uH.

If we select type 61 Ferrite material on a FT-37 size core, 16 turns measures ~15.4uH ....close, but OK! We also want the lowest possible series inductive reactance of the single turn on the transformer. For the FT-37-61 that now measures 0.06uH.....GREAT! Note that type 43 material has a permeability 20x that of type 61 material and is not acceptable. For higher frequencies, we want to reduce the length of the transformer windings to "well below a significant fraction of a wavelength". We use a little more than one foot..... OK. We also want to reduce the turn-to-turn capacitance which can be achieved to some degree with insulated wire. Teflon insulated #30 wire is great but "slick" and a little difficult to wind. Kynar insulated #30 wire is easier to work with and has a slightly smaller diameter. I decided against using a "binocular" Ferrite core (although the board layout is wired to accept one) because the small ones are too difficult to wind with more than 10-12 turns and the larger ones have too much single turn inductance. I don't think we'll have a heat problem with FT-37-61 cores but there is always the FT-50-61 core or multiple FT-37-61 cores. The board layout will accept either one.

Milt Cram, W8NUE, ran simulations and mathmatical analysis on the design and so have I. Data indicates low insertion loss and relatively accurate SWR representations for 10 to 250 ohm resistive termination impedances. Complex impedances are more difficult to measure accurately.....tell me about it.

After all the above is said and done, MANY experiments run, MANY diodes purchased, and MANY prototype boards built (most which are now "drink coasters"), we narrowed in on an acceptable design. Two boards... a Directional Coupler board with all the RF and only the detect signals coming off the board and an ADC/Microcontroller board with no RF (that was the intent anyway). The best results for 160m to 6m were seen with two dual FT-37-61 cores with a 23 turn winding of #26 wire and a 1 turn winding of shielded wire.

Since all diodes are non-linear how do we compensate for that in order to calculate accurate Forward and Reflected power ? Well......Why not use the floating point math power of the modern microcontroller and a "few" 2nd or 3rd order polynomials to perform curve fitting ? Sounds interesting to me and I ended up with 18 polynomials. After enlisting the aid of John Fisher, K5JHF, and Milt Cram, W8NUE, to work their firmware magic, and Ben Bibb, NO5K, to make some accurate measurements in his well equipped lab, we're off to the races.

So what comes in today's mWattmeter kit ? .....Bill of Material:

The price for of this Digital QRP mWattmeter II kit #9 is $55 (just like the mWattmeter I kit) plus $5 postage in the USA and $12.75 postage for DX.

In case you were wondering about the nice Bezel, they are available from Digi-Key and are part number PRD360B-ND.


The SDR2GO Kit #10

Now for the most ambitious and complex kit of them all .... a SDR Hardwarwe/Firmware Development Platform which nets a pretty nice Software Defined Radio Transceiver and does --NOT-- require an external computer. This makes it highly portable .....hence "SDR2GO". The idea here is to also not duplicate existing hardware which you may already have by using existing I/Q frontends, like the various SoftRock Rx/Tx units, UHFSDR, SR63ng, etc.

SDR2GO Builder's Notes V1.9x

SDR2GO Builders Notes V2.0

SDR2GO Bootloader Notes

SDR2GO Graphics Interface Notes

SDR2GO dsPIC33 HEX Code V1.9.0

SDR2GO dsPIC33 HEX Code V2.0

All SDR2GO kits are now shipping with the V2.0 full code which includes the bootloader code.

Be sure to check out kit #17 which provides an optional Graphics Interface for the SDR2GO. Graphics is required to take advantage of several functions provided in V2.0.

K5BCQ's first SDR2GO (board on the left) with SoftRock RxTx V6.3 (boards on the right). Keyboard is plugged into the back for convenient data loading and setting .....you can also use the rotary encoder. Many of the switches shown will be replaced with encoded BCD switches for future use.

Ben Bibb's, NO5K, SDR2GO with a UHFSDR board.

Ben Bibb's, NO5K, SDR2GO Transceiver, front view.

Riku Luostari's, ZL1KLP, compact packaging of a SDR2GO ....to go.

Yes, Virginia, there really is a SDR2GO. This unit takes the place of the computer and uses an existing I/Q frontend such as a SoftRock RxTx, SoftRock Ensemble RxTx, UHFSDR, and others. It is the work of mainly four hams; Charley Hill, W5BAA, who started this (and thus, deserves most of the blame/credit), John Fisher, K5JHF, Milt Cram, W8NUE, and myself Kees Talen, K5BCQ.

The major features are listed below:

The SDR2GO uses a dsPIC33JF128GP804 microcontroller for the DSP functions and a MC9S08SH32CWL for Si570 tuning, keyboard interface, alphanumeric display control.

Some New Additions (from The Si570 Controller Kit #2):

The unit is really a platform for firmware development (come and join in) and general SDR experimentation. As such, there is quite a bit of flexibiliy designed in (some of which, bit me) and there are several available interfaces for future expansion.

All that said, it makes a real nice low power CW/SSB rig "as is".

For our first trials, 30 V1.x kits were built and they are out there being used and refined (including trying to come up with good documentation). To be honest, this is NOT an easy kit to build because it has parts such as a 32 pin QFN CODEC TLV320AIC3204 (best part for our needs that we could find and only available in that package). It also has a 44 pin QFP and a SOT-6 package.

So what comes in today's SDR2GO kit ? .....Bill of Material:

The price for the SDR2GO Kit #10 is $73 plus $5.00 postage in the USA and $12.75 postage for DX.

Optional parts: CMOS Si570 chip $15, LVDS Si570 chip $20, MiniCircuits TC1-1TG2+ RF Transformer $2, FIN-1002 lever converter for LVDS $1.

Just to show other hams what a "state-of-the-art, volume manufacturing" operation this is, here is a picture of the two low cost homebrew fixtures used for programming loose Microcontrollers and the debug tool to verify programming success. Hey, QFP clamshells cost big bucks and this one will accept 44 pin to 64 pin devices.

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I didn't know whether to put this at the top or bottom of the SDR2GO section, but here it is ....

"GOTCHA, OOPS, @#$!!, HUH??" SECTION ......based on questions