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 yet 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. There are two versions of the code which you need to specify when ordering ....."T" (Toggle) which will automatically toggle between degrees F and degrees C every 5 seconds ("T" is the default if you do not specify "T" or "F") and "F" (Fixed) which will read degrees F without the jumper "J1" installed and degrees C with the jumper "J1" instsalled. 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 is the packaging used by Bill Sepulveda, K5LN, using a vinyl overlay printed with a color printer. He described the technique in a Dec, 2002 QST article and it will also cover up small holes and other "oops" marks on the panel.

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).

-------------------------------------------------------

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.

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.

ERATTA: It has been brought to my attention that some of the MCB-II boards don't have thermals on the R2 ground pad and therefore that point is not grounded. The fix is relatively simple. scratch some of the adjacent ground soldermask off and bridge the bare copper to the ungrounded resistor pad with solder. The second problem is that C3 is labeled but the pads are missing. The fix is to solder C3 on the bottom, between pins 3 and 4 of the microcontroller socket.

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 Stamp Amp Kit #8

Small Audio Amplifier board with 26/46 dB Gain. This shows the old one and the new kit board now offered.

This was a quick Audio Amp using a single power supply DIP OpAmp. You never know when you need one ....or two. Powered by 5-6V DC.

So what comes in today's Stamp Amp Kit ? ......Bill of Material:

The price for the Stamp Amp kit #8 is $10 plus $3 postage in the USA and $9.50 postage for DX.


The Digital QRP mWattmeter II Kit #9

K5BCQ's mWattmeter II packaging scheme using a "Royal Crown" LMB #CR-531 box.

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.

I have decided to retire this kit to a new home and all boards, parts, and documentation are now in the able hands of Ron, W4MMP, W4MMP"at"aol.com This was a really fun kit to develop.


The SDR2GO Kit #10

I am out of boards/parts and have decided to retire this kit because the programming support is now directed to the STM32-SDR kit with it's color graphics touchscreen and much higher performance microcontroller. The SDR2GO kit was a really great SDR Development platform.

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


The ThumbTach Kit #12

The ThumbTach is the small board in the middle. It's connected to a 4.5VDC (5V) power supply and a DSO nano-Scope which is showing the 60Hz output from the overhead lamp (120Hz on the screen).

This is a little tachometer circuit developed to measure propeller speeds on model airplanes. It also has many other uses measuring rotational speeds via changes in light. The detector is a simple photo-transistor driving an Op-Amp. This photo tansistor was picked to be most responsive to visible light.

The output is pulses as can be seen on the scope. You may use it to drive a counter circuit or whatever.

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

The price for the ThumbTach Kit #12 is $6 plus $3 postage in the USA and $4 postage for DX.


The Attenuator Kit #13

Two assembled Attenuator Kits, showing the back and front sides.

This was developed as a crude but simple HF Attenuator after I had miserable reliability problems with commercial attenuator switches. The attenuation would change depending on how the switches "felt" that day. Very difficult to get repeatable results. I also tended to stress the attenuator resistors because of their 1/4W rating. This kit provides Vishay 1W 5% resistors and uses jumper vs switches. Sure, they makes it a little more time consuming to change values, but the jumpers provide very positive contact and if they wear out .....get another jumper, they only cost 1 cent each and extras are included in the kit. Due to the "Open Design", I would not use this above HF frequencies.

It has served my needs, does what I need an attenuator for, and will work for you too.

The kit can be provided with BNC connectors as shown or SMA board edge connectors. Your choice to specify, same price.

OK, OK, so the jumpers are a little cumbersome if you change them often so we'll offer an option to replace the 9 2x3 Headers and 25 Jumpers with 9 nice APEM 2P2T slide switches for an additional $5.

What the one with the switch option looks like.

Ben Bibb, NO5K, checked this Attenuator in his lab and was very impressed. The SWR at 6m is only 1.2 and the SWR at 2m is only 1.4. Lower frequencies are, of course, better with a SWR of 1.0 to 1.1. Ben also found the accuracy of the attenuation to be within 1-2% and the Return Loss levels are very acceptable. Insertion loss is a fraction of a dB. Those 1W Vishay 5% resistors are good ones and cost $0.16 each. Overall not bad for a $20 open board Step Attenuator. Those slide switches are made in the USA and good for 50,000 cycles.

So what comes in today's Attenuator Kit ? ......Bill of Material:

The price for the Attenuator #13 is $15 (or $20 with slide switches) plus $4 postage in the USA and $9.50 postage for DX.


The 20W HF Amplifier II Kit V1.5 #15

The 20W HF Amplifier II shown. The SMA connectors (board has the footprints) were installed for my testing, the kit is provided with 50 ohm coax to connect to the BNC/SMA/HF connector of your choice. Normally the Ampifier would be mounted inside an enclosure with a hole so the MOSFETs can be bolted directly to the outside heatsink.

Shows some more detail of T2 and T3 mounted on the Amplifier board.

Shows some detail of T3 assembly steps.T3 is made up of two sleeve ferrites on 3/16" copper tubes soldered to a 1/32" copper plate on one end. The secondary is 2 turns of #20 stranded and Teflon coated wire. The 1 turn primary is connected to power via a Phasing Choke, T2.

T2 is the phasing choke and is made using a BN43-302 Binocular core with 1 hairpin turn of #20 bifilar wire. The bifilar wire is made from two 2" sections of #20 enameled wire (not twisted) throught 1-1/8" of 3/32" shrink tube. The shrink tube holds the wires tightly together in parallel and forms the bifilar turn. The turns are connected in series with power connected to the center terminal. The picture ought to clear up questions.

Never wanting to leave well enough alone, the 20w Amplifier I has been replaced by the 20W amplifier II. The main differences are adding some surface mount components, replacing the two output transformers with a single homebrew OPT as shown above, much better (lower DC loss) RF chokes, reducing the SOX timeout by changing the capacitor from 10uF to a lower value, and providing an optional drilled and tapped heatsink (no fan required) from HeatsinksUSA. The new OPT does not run hot at all.....even with 25W+ applied and efficiency, although not measured, appears "better" than previous designs.

20W Amplifier I, V1.3B, Construction Hints

20W Amplifier I, V1.3B, Schematic

20W Amplifier II, V1.4, Construction Hints

20W Amplifier II, V1.4, Schematic

20W Amplifier II, V1.5, Construction Hints

20W Amplifier II, V1.5, Schematic

When it comes to Amplifiers, the Radio Amateur is responsible for making sure his amplifier operates within the guidelines established by the FCC and that it does not cause unwanted ipassnterference. This is a Broadband Amplifier and will require some sort of Low Pass Filter (LPF) or Band Pass Filter (BPF) on the output to attenuate harmonics. You may already have one you intend to use.

Amplifiers have been around a long time and continue to evolve, one design being based on another, etc. I want to give credit to some who “plowed the ground” before me: G6ALU, KE9H, WA2EBY, TF3LJ, K5OOR and above all NO5K who provided all the testing in his extensive lab. The question may come up, “Why ANOTHER Amplifier ?” To that I say, “Looks like fun, why not ?”

My idea was to provide a good and low cost Amplifier for the HF bands (160m to 6m) which can be driven by a SoftRock SDR or any other low power driver and provide ~20dBm of gain. Low power being defined as less than 1W. Some of the new SDR units supply less than 50mw and really need a little “boost”. This Amp uses well received RD16HHF1 RF MOSFETs which are each rated at 16W output for 12.5VDC at 30+MHz. These parts are quite robust and much better than the IRF510 Switching Power Supply MOSFETs used earlier, largely because of their low cost and availability. The other advantage of the RD16HHF1 is that the mounting tab is attached to the “Drain” pin which is at ground potential …so no mica insulator is required. The Amplifier has a Signal Operated Switch (SOX) for CW QSK. I didn’t really put it there for SSB …..but who knows (still better to use PTT). Did I mention good and low cost ?

The design and components which have been selected require that the operational criteria of 1) an Input of 1W max –AND-- 2) an Output of 20W max ………whichever comes first, NOT be exceeded. To allow some adjustment, the input to the Amplifier has places for a Pi network Input Attenuator of your selection (Rx, Ry, Ry) ….3dB, 6dB, etc. Parts for a 3dB (50% power reduction) attenuator are provided in the kit. The purpose of the attenuator is to reduce input power and to provide proper 50ohm matching for the driver. This design has been extensively tested and optimized to provide good matching to 50ohms without the attenuator. If you elect to not use an attenuator, replace Rx with a jumper and do not install either Ry.

1Mhz to 61Mhz Power Profile of 20W Amplifier II showing relatively flat output..... 43dBm is 20W. This was with a 3dB on board attenuator so the Amplifier is driven by a constant 500mW (1W into the attenuator). The lower line is with a constant 250mW drive (500mW into the attenuator) and shows lack of compression indicating great linearity. Try that on some of the other Amps out there. To attain "20W", you can crank the drive up slightly while maintaining the 1W max input to the Amp and 20W max output from the Amp as specified.

The design provides Class A/B linear operation for (all Modes). This means that both MOSFETs -MUST- have their gate bias adjusted and balanced so they are the same on both devices. The actually current required is between 250mA and 500mA. You determine the optimum level for your application, power supply voltage, etc. Do not exceed the 500mA gate bias per MOSFET. This is simple to set up. After assembly, with the MOSFETs screwed to the heatsink and the Bias switch closed (shorts R2), turn the bias potentiometers fully counterclockwise, connect a 50ohm load to the input connector and to the output connector, put 12V on the PTT input to pick the Rx/Tx relay and and turn on the 6V bias regulator. Now measure the current. There should be a small current draw. Turn one bias pot clockwise until the current increases by 300mA, then turn the other bias pot until the current increases an additional 300mA. Now the bias levels are balanced and set for Class A/B operation for your Amplifier. Since linearity gets worse at the higher power levels, you may want to experiment with R/C FeedBack values .....the footprints are on the board. Be sure to use 1KV rated capacitors, not 25/50V rated capacitors, for "C" to protect the MOSFETs. That's experience talking.

The design also provides Class C operation (CW only). This allows lower power consumption when you really don’t need linear operation. A single resistor reduces the Gate Bias current on both MOSFETs to around 25-35mA each. Testing has shown them to remain adequately balanced. You can also use the potentiometers to adjust this if you prefer and only want to run Class C (for CW).

Many MOSFET Amplifier circuits do not use a feedback circuit but I thought it would be good design practice to do so and added one. It's not used but, at least, the component footprints (C,R) are there if we need them later. The T3 compensation capacitor is made up of Qty 2, 249pF Mica capacitors in series.

Another design parameter which seems to help on all the bands, especially 6m, is to further reduce spurs by paralleling capacitors of different values to reduce the capacitor self resonance effects. You will see that in many cases a 100nF cap is in parallel with a 47nF cap or 10nF cap and also a 1nF cap.

So what comes in today's 20W amplifier Kit ? ......Bill of Material:

I now offer 2 heatsink alternatives for the 20W Amplifier (board measures 2.5" x 3.5").

#1) No Heatsink/fan, Just the 20W Amplifier II for $55, you come up with your own AM-2 Heatsink/fan or whatever Heatsink you want to use. The amplifier was originally designed for a computer type AM-2 heatsink .....or whatever heatsink you have laying around.

#2) A 4.23" x 2.90" x 1" Heatsink from HeatsinksUSA. This Heatsink has 11 fins and is drilled and tapped to match the board. I am the driller/tapper. Price will be an additional $15. Postage will go up because of the added weight.

Shipping for one kit with option #1 (NO heatsink) is $5 First Class Mail in the USA and $9.50 First Class Mail for DX. Shipping for a kit with a Heatsink option in the USA will be $6 for a small Priority Mail Box. DX shipping costs are determined by location.


EXTERNAL LOW PASS FILTERS.....7 Band Relay Switched LPF Board.

I have retired this board since I'm out of parts and want to focus on Manual/Relay BPF/LPF boards using the little plug-in filters described below.


EXTERNAL FILTERS ......Individual Plug-in BPF and LPF filters.

Shows several BPF and LPF boards

These boards all have a 2.5" x 0.6" form factor and come in two varieties, BPF or LPF. Redundant header pins are located at both ends (or you can solder directly), The designs are symetrical so the boards can be reversed or flipped without effect. The boards can be used standalone and plugged one at a time or used with a switcheable host board of your design or mine (available later). I have the bare boards only and header pins available for $2 per board plus postage in the USA. Toroids are listed below (the capacitors are all 630V or 1KV NPO 1206/1210 size SMT. You would use one of the free programs like Jim Tonne's, ELSIE, or other filter program (AADE, etc) for the appropriate values for your needs.

The schematic is shown here:

BPF and LPF board schematic


Toroids for external Low Pass Filters are not very expensive and W8DIZ suplies a wide variety at reasonable cost. If you need 25-100 of those you are better off to order directly from W8DIZ. Since I've had some requests and if you only need a few, here is my list. They all came from W8DIZ:

AVAILABLE TOROIDS Feb 31st, 2013


500V Mica caps for Low Pass Filters are pretty expensive so I'm offering these out of my stock.

AVAILABLE MICA CAPACITORS Feb 31st, 2013


The Graphics Interface for the SDR2GO Kit #17

I am out of boards/parts and have decided to retire this kit because the programming support is now directed to the STM32-SDR kit with it's color graphics touchscreen and much higher performance microcontroller. The SDR2GO kit and the suporting Graphics Interface kit was a really great SDR Development platform.


The WB6DHW Band Pass Filter Kit #20

The WB6DHW BPF Kit with toroids, top view. Note that I mounted the toroids on the bottom of the board to reduce interference with other components. The SMA connector in the picture is for my testing.

The WB6DHW BPF Kit with toroids, bottom view. That's a lot of little toroids to wind ....but it does have higher "Q" (less insertion loss). You can adjust the turns spacing to get closer to the "target inductance" on the provided sheet.

The idea here is to offer a complete BPF kit based on the board offered by Dave, WB6DHW. I know it's difficult to buy all the various parts in small qtys so this is an attempt to help out. As you know, the values Dave selected, using the great L/C filter program from AADE, provides 6 overlapped BPFs which cover from 1.5MHz to 30MHz. Note that none of the passbands include harmonics. In other words, the highest passband frequency is less than 2X the lowest passband frequency. I refer you to Dave's, WB6DHW, website for schematics and additional details.

I have made a few minor modifications which are detailed in the instructions which come with the kit. Basically for the larger inductances, I use 2 stacked cores to cut down the turns count, a different 1:1 RF transformer is used, and you have the option to install L44 or a 1N914A diode for "accidental 5V power reversal protection" which will cost you both FETs.....been there, done that.

Since many of you have ordered the board from Dave already and may not have gotten around to ordering all the remaining parts (or like me, couldn't find it), I offer the option of buying the BPF Kit with or without the board. OPTION #1

The lowest BPF insertion loss will be if you use handwound toroids. This is not easy, there are 42 of them, and it requires a steady hand, good magnifier, and patience, patience. You may want to enlist the aid of a young type person. The cores come with 20ft of Belden #28 Thermaleze wire. OPTION #2

Some of you may not want to undertake the task of winding 42 REALLY SMALL toroid cores, and you have the option of selecting 0805 size chip components which are easy to solder and no winding is required. Although I have selected chip inductors with high "Q" levels, they still have slightly higher insertion loss as shown by the comparison BPF plots on the AQRP website on yahoogroups.com (under my call and BPF #20).

We are trying to find a local person to wind the toroids and provide pre-wound sets....but that has not been worked out yet and I have no idea of the costs involved. The only thing that is certain is that it won't be me.

CONSTRUCTION and TESTING HINTS:

It's best to unpack the envelopes and especially the capacitor/inductor sheets over a large piece of white paper so you don't accidentally "ping" small parts into the carpet. Remove only one capacitor/inductor value at a time and get it soldered in place. It's also best to put the cat in an isolated room.

For initial testing, check continuity across each filter from the filter side of each 100nF DC blocking capacitor on the input and output. The resistance should be less than 1 ohm. To check the 3-bit filter selection for the 8 possibilities, measure the voltage on the outside of the DC blocking capacitors. When a specific filter is selected you will see +2.5V on the 100nF DC blocking capacitors for that filter. Don't forget to measure the two filter positions which will be used later.

So what comes in today's WB6DHW BPF Kit ....other than a --LOT-- of small parts ? ...Bill of Material:

OPTION #1 Bill of Material:

OPTION #2 Bill of Material:

OPTION #3 Bill of Material:

The price for the WB6DHW BPF KIT #20 is $15, plus $9 for OPTION #1 (if you don't already have the board ....or can't find it), plus $10 for OPTION #2, plus $10 for OPTION #3, plus $4 for postage (for 1 or 2 kits) in the USA and $9.50 for DX postage. You can order option #2 AND/OR option #3, but you only --need-- one of them. Options can only be ordered/shipped with a kit.


The 5W HF Amplifier Kit #21

The 5W HF Amplifier shown with the new optional Heatsink. The SMA connectors were installed for my testing, the kit is provided with 50 ohm coax to connect to the BNC/SMA/HF connector of your choice. Normally the Ampifier would be mounted in an enclosure with a hole so the MOSFET can be bolted directly to the outside heatsink.

Picture of the optional drilled and tapped heatsink.

It would be nice to have an Amp with a little less power than the 20W amplifier Kit #15, so here is a 5W version using a single MOSFET with an optional drilled and tapped heatsink (no fan required) from HeatsinksUSA.

When it comes to Amplifiers, the Radio Amateur is responsible for making sure his amplifier operates within the guidelines established by the FCC and that it does not cause unwanted ipassnterference. This is a Broadband Amplifier and will require some sort of Low Pass Filter (LPF) or Band Pass Filter (BPF) on the output to attenuate harmonics. You may already have one you intend to use.

My idea was to provide a good and low cost Amplifier for the HF bands (160m to 6m) which can be driven by a SoftRock SDR or any other low power driver and provide ~20dBm of gain. Low power being defined as ~100mW. Some of the new SDR units supply less than 50mw and really need a little “boost”. This Amp uses the RD06HHF1 RF MOSFET which are rated at 6W output for 12.5VDC at 30+MHz. These parts are quite robust and much better than the IRF510 Switching Power Supply MOSFETs used earlier, largely because of their low cost and availability. The other advantage of the RD06HHF1 is that the mounting tab is attached to the “Drain” pin which is at ground potential …so no mica insulator is required. Just like the 20W HF Amplifier Kit #15, this Amplifier has a Signal Operated Switch (SOX) for CW QSK. I didn’t really put it there for SSB …..but who knows (still better to use PTT). Did I mention good and low cost ?

The design and components which have been selected require that the operational criteria of 1) an Input of ~100mW –AND-- 2) an Output of 5W max ………whichever comes first, NOT be exceeded. To allow some adjustment, the input to the Amplifier has places for a Pi network Input Attenuator of your selection (Rx, Ry, Ry) ….3dB, 6dB, etc. Parts for a 3dB (50% power reduction) attenuator are provided in the kit. The purpose of the attenuator is to reduce input power and to provide proper 50ohm matching for the driver. This design has been extensively tested and optimized to provide good matching to 50ohms without the attenuator. If you elect to not use an attenuator, replace Rx with a jumper and do not install either Ry.

The design also provides Class C operation (CW only). This allows lower power consumption when you really don’t need linear operation. The Gate Bias current on the MOSFET is set to around 20mA with the potentiometer if you prefer and only want to run Class C (for CW)....much less heat generated.

Many MOSFET Amplifier circuits do not use a feedback circuit but I thought it would be good design practice to do so and added one. The T2 compensation capacitor is a 249pF Mica capacitor. This value seems to work best for 160m to 6m (emphasis was put on working well at 6m), and Mica capacitors are very stable across a broad range of frequency and temperature.

Another design parameter which seems to help on all the bands, especially 6m, is to further reduce spurs by paralleling capacitors of different values to reduce the capacitor self resonance effects. You will see that in many cases a 100nF cap is in parallel with a 47nF cap or 10nF cap and also a 1nF cap.

Here are the assembly Instructions for the 5W Amplifier

5W Amplifier Construction Hints

5W Amplifier Schematic

So what comes in today's 5W amplifier Kit ? ......Bill of Material:

I offer two heatsink options:

#1) No Heatsink, Just the 5W Amplifier for $35, you come up with your Heatsink

#2) A 4.23" x 2.90" x 1" Heatsink from HeatsinksUSA. This Heatsink has 1 hole drilled and tapped to match the MOSFET and 2 mountin holes. I am the driller/tapper. Price will be an additional $5. Postage will go up because of the added weight.

Shipping for one kit with option #1 (NO heatsink) is $4 First Class Mail in the USA and $9.50 First Class Mail for DX. Shipping for a kit with Heatsink option in the USA will be $6. DX shipping costs are determined by location.


The Si570 Low Frequency and I/Q Output Adapter Board Kit #22

This board was designed to be used with an Si570 Frequency Controller (Kit #2) or any Si570 (SoftRock for example) to provide outputs lower than 3.5MHz by dividing the input signal by 10 or 100 AND provide I/Q signals for mixer experimentation. The board show is set up for Divide by 100 AND Provide Quadrature QSD/QSE I/Q signals

This little board was designed to be used with an Si570 Frequency Controller (Kit #2) or a SoftRock to provide outputs lower than 3.5MHz. Jumper selection of divide by 1 (bypass), 10, or 100 will provide down to 35KHz. This is something useful for the LF guys. You would then feed that signal to a QSD or QED for detection at ¼ of that frequency.

You can also jumper select an I/Q output in addition to divide by 1, 10, or 100. This could be used with your own external mixer or other experimentation.

The construction is pretty simple ….solder all the parts on the board and pay attention to where you have all the jumpers set. All the resistors are the same, except for the 0 ohm "Jumper", and all the capacitors are the same. The 16 pin smt IC goes on the 16 pin footprint and the 14 pin smt IC goes on the 14 pin footprint. The #1 pin on the connectors is shown as a square pad on the footprint.

Power/Ground is taken from the Si570 Controller output connector which has 3.3V or you can attach it externally to 3.3V or 5V on a SoftRock or whatever you are working with. Both chips on this board will run off 3.3V or 5V and have slightly better performance at 5V.

So what comes in today's Si570 Low Frequency and I/Q Output Adapter Board ? ......Bill of Material:

Kit #22 sells for $12 and shipping is $3 First Class Mail in the USA and $7.50 First Class Mail for DX.


The Octal Swizzle Board Kit #23

This board can be used to transform any Octal (3 bit) pattern to any other Octal (3 bit) pattern. The color jumpers are for testing purposes and will be replaced with #30 teflon wire on the back side for normal use.

What is it ? A board which can be used to transform any Octal (3 bit) pattern to any other Octal (3 bit) pattern using the brute force of a 74LV138 Decoder and a 74HC148 Encoder. All the signals have 10K pullups. You are given multicolor jumpers to experiment with and some #30 wire to finalize the job since the #30 wire on the bottom of the board looks much cleaner. You will want to experiment because of Hi active and Low active devices. It's only 8 wires but you will have to scratch your head.

Why this board ? Makes the 3 control lines from your SDR2GO, STM32-SDR, manual switch, etc much easier to wire if the BPF control lines and the LPF Band control lines for the boards you are using are different.....for whatever reason.

This can be readily demonstrated for those using Dave's WB6DHW BPF for "Receive" and some other LPF board for "Transmit" on your transceiver.....or if you are just using a junkbox switch.

The logic will work with 2V to 6V signals. If you are connecting to a 3.3V interface which already has pullups, remove the three 10K to 5V pullups on this board.

Example:

Using Dave's, WB6DHW, suggested values and schematic you have the following BPF board controls:

For this example I have a pushbutton switch which reads "0" to "7" and has a 3 bit output to ground as follows: Since everything has pullups, an open switch bit will be "Hi" and a closed one will be "Lo"

I want the pushbutton octal switch with 3 bit output to control the BPF as follows:

So I map (jumper/wire) the two connector rows which are labeled 1-8

Hope that does not confuse anyone (may require some paper and pencil). There is some ERATTA (Murphy is ever present). One of the three input pins is not connected to it's pullup resistor (1/8" trace missing). This is easy to correct by bending that lead and soldering it directly to the 10K resistor pad. You can see the 'fix" in the picture.

So what comes in today's Octal Swizzle Board ? ......Bill of Material:

Kit #23 sells for $15 and shipping is $3 First Class Mail in the USA and $7.50 First Class Mail for DX.


The T/R Switch Kit #24

This is a simple T/R Switch board.

What is it ? A board with a nice G6H-2F 5VDC Omron relay with dual, bifurcated, and gold plated contacts which can be used to switch a coax line between Receive (Normally Closed) and Transmit (Normally Open). The coax connectors are SMA type connectors or you can solder coax directly to the board (SMA connectors are a much better idea). The control signal is 5V active. If you want to use 12V for the relay, put a 270 ohm resistor is series with the power.

So what comes in today's T/R Switch Board ? ......Bill of Material:

Kit #24 sells for $10 and shipping is $3 First Class Mail in the USA and $7.50 First Class Mail for DX.


The AQRP Vector Impedance Analyzer kit #25

An assembled AQRP VIA showing a Smith Chart. It can also plot parameters across a range you define and can provide parameter data screens

Shows the 3 board stack using the STM32F407-Discovery board. Programming updates are via the USB connector to your computer. Two, 3 cell each, battery packs are shown.

Shows the VIA board with the RF bridge, attenuators, dual SA612A mixers, audio CODEC, Si5351A frequency control, memory, and interface to the TFT Display and STM32F4Discovery board.

Milt Cram, W8NUE, and I decided we wanted to use some of the great development kits out there which are available from various manufacturers at VERY reasonable prices to entice users to design and write code to use "their" products. This coupled with "free" Development Tools is an easy sell for us. The STM32F407-Discovery boards are available for $14.88 and have plenty of microcontroller capability and features.

Milt drew on his SDR2GO microcode experience, code he used for the NUE-PSK Digital Modem, and also the more recent STM32-SDR code. He decided to base the design on audio baseband I/Q signals and process those for the required data. This is done by using TWO synchronously tuned RF signals F0 and F0+2KHz ....one for the device under test and the other for the dual I/Q mixers. This has the unique advantage of being able to readily process negative complex numbers correctly .....a problem with many mid range commercial antenna analyzers out there.

After looking at several possibilities, including the little NOKIA touchscreen, we decided to go for something far more usable and user friendly. Here we have it; The AQRP Vector Impedance Analyzer kit #25.

Milt presented the design at the Austin Summerfest QRP Forum on August 7th and 8th of 2015 and I decided I better get something up on the website.

It's a standalone, battery powered, Vector Impedance Analyzer for portable operation. Can be used to check antennas, filter designs, etc, etc. This design will evolve over time as changes and improvements are made to function and visual presentation. The STM board microcode is easily updated by using STM-LINK software (free) and a USB cable.

AQRP VIA V1 Construction Hints

AQRP VIA V1.5 Schematic, page1

AQRP VIA V1.5 Schematic, page2

AQRP VIA HEX Code V1.01

AQRP VIA board higher resolution of top

AQRP VIA board higher resolution of bottom

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FEATURES:

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SAMPLE VIA SCREENS

Using a test circuit consisting of a 14.3MHz series resonant RLC.

VIA Data screen using the test circuit above, tuned to the frequency indicated.

VIA Return Loss screen using the test circuit above, showing a vertical cursor and it's frequency.

VIA Impedance screen using the test circuit above, showing the vertical cursor and it's frequency.

VIA Reflection Coefficient screen using the test circuit above, showing the vertical cursor and it's frequency.

VIA Smith Chart using the test circuit above and scanning 3MHZ to 30MHZ

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BILL OF MATERIAL

So what comes in today's AQRP Vector Impedance Analyzer kit ? ......Bill of Material:

This is not a Heathkit with each part labeled. The resistors are all black and laser marked with their values. The capacitors are all brown or grey and will be marked if there can be confusion. I don't consider a strip of 10 100nF (unmarked) capacitors and a strip 5 10nF (unmarked) capacitors when the Bill of Material calls out those quantities......to be confusing. If there are two strips of 5 capacitors, they will be marked.

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USING THE AQRP VIA

Turn the VIA on and you should see the “splash screen” showing W8NUE’s beam antenna and information on the VIA software including the microcode level which starts at “V1.01”. This will be followed by the “VIA Setup” screen. ……What you REALLY needed to do first is calibrate the touchscreen and the 50 ohm, 0 ohm, and stray capacitance parameters but we figure you are going to turn it on to see what happens first.

Turn the unit off and power it up again with both rotary encoders pushbuttons pushed “IN”. This will bring up the touchscreen calibration routine …….just follow the instructions.

On the VIA Setup screen push “CAL” and follow the instructions, attach a 50 ohm load, a short, and open when requested, check to see if the data is within range and save that data. The unit is now calibrated.

Using the setup screen you can define a Start frequency, a Stop frequency, Step size (frequency step between readings), and Dwell time (time between readings to allow the line to settle) . Be sure and save these parameters before leaving the screen. Feedback will be provided on the screen. You can also select Auto or Manual mode. In Auto mode the unit will scan per the parameters you entered. In Manual mode you tune the Frequency with the #1 Rotary Encoder (on the unit shown, that is the bottom knob).

In Manual mode you will see a number of parameters pertaining to measured data. You also have the option to got to “Setup” again, “Auto”, or “Plot”. In “Plot” you have the ability to select various data plots VSWR, Impedance, Admittance, etc. If the data is a complex number the left axis will show the real “R” component and the right axis will show the imaginary “–j” component. The width of the horizontal scan will be adjusted to reflect the Start frequency and Stop Frequency you entered earlier. When the scan is completed and the Stop Frequency is reached (in Manual or Auto mode), the cursor bar is enabled with the frequency shown on the screen. The cursor is tuned by the #2 Rotary Encoder (on the unit shown, that is the top knob).

In Auto mode you can watch the plots being automatically generated. The cursor is enabled when the scan is complete.

Pushing the #2 Rotary Encoder at power up enables the LF mode (8kHz to 1MHz) and allows you to scan from a lower frequency of 8KHz. Handy for looking at that 134KHz antenna or checking that speaker Impedance ;o). You may have to change some of the RF capacitors (C2 and C3) to larger values (680nF-1uF) to increases the oscillator output to usable levels. With the capacitors supplied with the kit, the lowest frequency for reliable measurements is about 30kHz. The VIA provides an indication of the level of the IF signal (--valid signals in Green, low level signals in Red).

We have a UART interface to your computer, an additional Si5351 RF output, an sPI Interface, another I2C Interface, and several other features not presently used. All those are TBD.

Try it, we think you will like it and it will give you a really nice visualization of the antenna you are receiving/transmitting with.

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PRICES

The price for of the above Kit without the STM32F407-Discovery board is $73 plus $6 postage in the USA and $13.70 postage for DX.

You can reduce the total by $12 without the TFT_320QVT display in the event you already have one.

I can provide a preprogrammed (latest level) STM32F407-Discovery board for $20 if ordered with a kit but there will be a 1 week delay in shipping because I don't intend to carry an inventory and will be ordering them from Mouser as needed. They are easy to program/reprogram in the field via the USB port on your computer. We will provide a link to the latest HEX files on this website.

Misc:

The little LMB Heeger Crown Royal enclosures look good and we use them extensively in projects. This is no exception and uses the CR-632 enclosure. We're not planing to provide enclosures. I'm sure there are many enclosure possibilities out there.



So what else are those AQRP guys up to ?? Well, lets see.........

This is the 6 band, manually switched, Band Pass Filter and Low Pass Filter board.

It consists of a 2.5" x 3.5" host board with up to 6 individual 2.5" x 0.6" BPF filters or LPF filters. It has multiple coax attach methods on the board: Coax cable directly with strain relief, BNC connectors, or SMA connectors.....your choice. Signal traces on the board are 50 mils and kept as short as possible with all wiring over a solid ground plane to minimize transmission line problems on the board.

The 6 bands on the switch are plug-in and can be any 6 BPF or LPF filters. The assumption being that for Tx you would probably want LPFs. However, if you want to use pluggable BPFs for both Receive and Transmit, that's OK too. The board can be configured so that the onboard Tx/Rx relay can be connected to either end of the symetrical plug-in filters.

In Mode 1 the relay armature switches the Antenna between the 6 plug-in filters and the Receive input. This assumes the receiver has it's own filters ......like Dave's, WB6DHW, broadband BPFs). In Mode 2 the 6 pluggable filters are connected to the Antenna at one end and the armature of the Tx/Rx relay at the other end. The relay selects between Receive and Transmit/Amplifier and the filters are inline to the antenna for both.

The relay is powered by 12V or 5 V, at 28mA and is controlled by external (Voltage active) PTT input. It has gold, bifurcated and redundant contacts for reliability.

The little 2.5" x 0.6" BPF/LPF filter (shown in the Kit #15 section, above) form factor is not a "standard" yet but they seem to fit in well with the size QRP SDR units around here (AQRP). I measured a couple of LPFs for 40m and 20m on my MiniVNA-Pro and the Transmission Loss was <0.1dB with a very respectable Return Loss so the SWR is low. Of course, all these maeasurements are into 50 ohms. BPF data looks good too but I haven't built them up and tested them for all the bands.

Some pictures showing more detail of the switch. The filters are symetrical and can be plugged right side up or upside down. You can locate the header pins on either side of the board and can come up with some very compact implementations. This compact technique works great for T37 cores. For T44/T50 cores, use additional spacers where needed.


This is the Si570 Controller II. You will note that it's just the bottom half of a SDR2GO board (above).

This is the Si570 Controller II which offers the same features described in the SDR2GO section. The main ones are "standard" backlit 16x2 display, keyboard input (as well as rotary encoder input), ability to display some user defined text, scanning capability, and enhanced frequency/display offset capability.

This kit is waaaaay on the back burner at this time .........and the burner is "off". I do have several boards available for $10 each, postpaid in the USA or $20 for a board and programmed microcontroller (only, no other parts), postpaid in the USA.