Updated November 14, 2013

Click here for my QRP-Tech Group Projects page

November 14, 2013 - Well I have tooooo many projects in the works and here I'm going to start another one. I've decided to layout a receiver pcb(s) to use with a N3ZI DDS2. Since this page is pretty full I'm going to start a W5DOR DDS/RECEIVER page.

September 9, 2013 - I've added my thoughts on a progressive receiver to this page.

May 5, 2013 - I'm now trying to build some of the "Projects" of the QRP-Tech Yahoo group. The first is Project-000 which is the DC receiver from the EMRFD book. Please fo to my Project-000 page for info.


April 16, 2013 - Learning to use my new Tektronix scope. Wow! what a difference from old 465B.

March 2, 2013, With the SS-40 receiver built I'm now turning to other related projects. Stay tuned to this page for more stuff.

February 4, 2013 - Fisnished the SS-40 receiver days ago. Just now getting some pix on here. Scroll down the large column to the right. BTW, it works!

January 25, 2013 - Now that we have a working SS-40 we need to put in an enclosure with nice knobs and an external power supply. Why external? Because we may want to use the SS-40 for field day where the power might come from SLA batteries instead of 120VAC.

January 19, 2013 - progress on the SS-40 rcvr. The power supply section works and the audio section works. See the main column to the right.

January 18, 2013 - assembling the SS-40 receiver. All is going well and all the circuits assembled so far are working correctly.

January 16, 2013 - Well, here I am again after some time off because of mentioned health problems. I'm still at work on several homebrew projects but some of my thinking has changed on where I want to go next. For instance, for a homebrew receiver I am putting together the SS-40 from 4SQRP group. Judging by their specs and from reports from others who have built this reeiver I believe its the way to go. I adtually have 2 kits. one I will built as it was meant to be and the other I will build with the intention of making it the basis for a progressive receiver. By that i mean I will replace the LO with a DDS osc and beaf up selectivity with the Hi-Per-Mite CW filter for a sharp 200Hz CW filter with no ringing and possibly a DSP DNR module from GAP. This should yield a great reciever with the 3 S's - sensitivity, selectivity and stability.

October 2, 2012 - Due to several health issues I haven't had time to add to this web recently. See home page for more info. I'm finishing up my DDS today by cutting out the rectangle for the LCD display. Already using that DDS for something not intended. I have another project that requires the same LCD display and can't get it to work. I'm using my DDs to test LCDs. A set of connectors for the DDS's LCD were installed and I can just plug in LCD's for testing. My current thinking about a QRP rig suitable for travel is using a modified SS-40 receiver along with a modified NS-40 transmitter both freq controlled by my DDS. I was quite impressed with the SS-40 specs.

August 18, 2012 - Got sidetracked by my DDS2 from N3ZI. needed an output buffer so layed one out with Expresspcb. Have 18 buffer pcb's on the way. See my project on my DDS2 project page.

July 31, 2012 -

Started building my "Oner" (1w xmtr)

July 29, 2012 -

Am building a super simple little transmitter called "The Oner". QST, Oct., 1994. Not that I need a little transmitter like the "Oner" but I wanted a simiple project to try out my new Manhattan style pads from QRPme.com.

July 25, 2012 -

Health issues have precluded any progress on my homebrew projects. Hope to be back at the bench within a week or so.

July 11, 2012 -

Well, if its not one thing it's another. Getting XYL ready for knee replacement surgery on the 16th. Getting a steroid shot in my knee today to get me through her surgery and recovery. Will only work on QRP homebrew if I can grab some time. Today I'm gonna add a list of publications that can help a homebrew ham. Go to my "Links" page and see "Publications" at top of left column.

June 29, 2012 -

Okay. We're finally started again. Go to DC Receiver section to the right and proceed down to the HB#2 illustrations to see pix of parts I'm getting started with.

June 28, 2012 -

Haven't entered anything here in a while. Was distracted. That doens't mean I wasn't working on these projects. I was distracted learning the design techniques for a Crystal Ladder Filter. I will post the articles and instructions I'v been using when I begin working on it again. Tomorrow I will return to the task of building the DC receiver.

June 14, 2012 -

WOW! Can't believe it. I have a huge junk box and don't have even one 1K pot. Have tons of 10K pots but not a 1K. Oh well. Fortunately I live near Houston and close enough to Mansfield, TX to get parts from Mouser in 1 day. If I order by 8PM I get it the next morning.

Have an old vintage HQ-170 (working) arriving today. Putting together the old rigs I had in 1955. Still need an AT-1, BC-342 and a Viking II.

June 10, 2012 -

After Church this morning and when I get back from grandson's basketball game that starts at noon, I'll get started on these projects. My carpal tunnel syndrome is under control and doesn't hurt as much when I use my right hand as it did before the surgery. I'll get this web site organized in such a way as to present my projects to whoever needs my experience for their own QRP homebrew efforts. I hope that viewers of this web will email me often with helpful comments and questions. email: gene at w5dor.com (replace the at with @ and remove spaces)

June 9, 2012 - Will now start again building the NE602/LM386 direct conversion receiver and when it is working I'll start adding circuitry to improve its performance. For instance, I want to build an audio system that I can later use on other receivers. Instead of just a speaker in a box I'll have an audio pre-amp/limiter into a audio filter for CW, then a DSP DNR system and finally into the power amp.

I assembled my DDS signal generator from N3ZI. I still need to install it in an enclosure and add an output buffer to drive 50 ohm line. I have purchased a couple of LH0063 Ultra-fast buffer amp for that purpose.

I received 4 very old heathkit transceivers today. The will provide me with enclosures and at least some very smooth tuning dial mechanisms. I may try to restore the 20m SSB unit.

May 21, 2012 - That's it. I've decided to proceed best I can with my health issues. Can't wait any longer. Happened on to a data sheet for a NE605. Found out it's a NE602 plus some more useful circuits like an IF amp and a RSSI output. It's really designed to be used as an FM rcvr but each circuit is brought out seperately on the IC pins. I can at least use the NE602 section plus the IF amp. I may try to use the RSSI output not only for a RSSI (S-meter) but filter it and try to use it for AGC.

But, I don't have any NE605 in stock so I'll proceed for now with the NE602 chips that I have.

April 22, 2012 - Added some references.

April 18, 2012 - My carpal tunnel syndrome has rendered my right arm all but useless for now. Surgery scheduled for May 31. Will take up projects when able.

April 15, 2012 - Well shoot! Health issues have slowed me down and to make matters worse the Mavs lost to the Lakers in overtime. I'll get something done when I can. I'll post to the homebrew and QRP groups when there something significant added here. But please comeby everyday !!! For some reason I spend a lot of time going through old publications looking for construction ideas. I have several ARRL handbooks - the oldest is 1955 when I first got my Novice ticket. I had one of my dad's old handbooks from the 30's but it was in such bad shape I threw it away. Wish I hadn't. Wish dad could see how the hobby has progressed and that because he mentored me as a kid I made a career and a hobby out of my love for electronics. I still remember him sitting at the kitchen table with me explaining about capacitors and inductors. And then, we built a 3-tube SW receiver that worked and that I spent hours at night listening to it. Good memories!!!

April 14, 2012 - Well didn't get it done. yesteday afternoon my carpal tunnel caused me to go rest a while . .which ended up as an all afternoon nap. Well, I'll try to get something done today.

April 13, 2012 - Today I will solder up my 1st mixer using the NE602 (or 612) with its associated VXO. I will also assemble the VXO for my QRP transmitter. I was just thinking. I could order a N3ZI freq counter and use it as a digital readout on my simple DC receiver.. . .or, better yet, I could build one myself using a 16F84 uC as a freq counter. Since the DC rcvr has no IF freq it would read the actual operating freq.

April 12, 2012 - and a homebrew group. I joined it also.

April 9, 2012 - Just found out that NARS has a new QRP group. I joined today and will be excited to work with the local hams on QRP homebrew projects.

April 6, 2012 - Well here we go. I have enough parts to get started. there was a slight delay 'cause I received my DDS VFO kit from N3ZI and was excited to get it going. I'll use that VFO later in this 1st project as a LO (local oscillator) for the receiver.

I also received a HF Mixer kit from partsandkits.com. I'll use the pcb from it since it's similar to the NE602 circuit I'm starting out with. The 1st version of this receiver will use the varactor tuned LO so some of the parts that came with the kit will work ok. My LO will not be the same freq. but will be close enough.


Homebrew Rig(s)


Sounds like a too big, almost unatainable project, doesn't it. Well here's what I have in mind:

1. High sensitivity
2. High degree of selectable selectivity for CW operation.
3. Low power drain
4. Ability to handle the strong as well as the weak signals.
5. Accurate digital dial down to 1Hz
6. RIT or Clarifier (ability to tune receiver a few KHz off the transmit frequency
7. Physically durable
8. Light weight
9. Include DSP DNR
10. Small but powerful external speaker with response suitable for CW operation
11. wo headphone output jacks w/separate volume controls
12. Large, heavy tuning knob
13. DSP noise blanker
14. Band switching with band select data on connector on rear panel
15. S-meter
16. AGC
17. Muting for QSK operation
18. RF gain control
19. AF gain control
20. Buffered IF output for SDR or panadapter (before narrow filter)
21. Lighted front panel for operation at night (LEDs)

Sounds like a lot but here's the plan. I'll start with the SS-40 4SQRP receiver described below. It has great sensitivity. In fact, more than is useful on the lower HF bands. . . about -133dBm MDS. I has a better dynamic range because it uses a diode-ring 1st mixer instead of the usual NE602. Of course we have to make up for the lost gain and the SS-40 does that by using a LT1253 IF amp. before and after the xtal filter.

CW selectivity is good with the xtal filter provided but need narrower filter for some situations like FD operation. I'll add a 4SQRP Hi-Per-Mite 200Hz filter that can be switched in if needed. That'll give me 500Hz and 200Hz selectivity.

Of course the rcvr is all solid-state to give us low-power operation but we'll keep that in mind as we go through this development.

The LO will be the N3ZI DDS2 that will give me 1Hz resolution, RIT and band switching.

I'll add a 2nd LM386 audio amp for the 2nd headphone output. Each amp will have it's own volume control and output jack. Handy for FD operation when someone else wants to listen in.

I'll use the large 75A-4 tuning knob with spinner.

For DSP noise reduction I can use the module from GAP and for noise blanker I have some ideas about a PIC controlled blanker that I'll design myself.

The N3ZI DDS2 has built in band switching. I'll use a PIC to read the freq and then select the proper input BPF. Therefore, band switching will be done simply with an Up and Down pushbuttons.



SS-40 4SQRP receiver is being buiilt and then progressively added to and modified to produce a simple but high-performance 40m receiver.


Future Projects:

There will be seperate pages/sections on this web site devoted to the projects listed below. Just click on the project name below to go to the web page(s) covering that project.

QRP rigs (see project progression below)

The "Oner" 1 watt CW transmitter
Winding Toroids
DDS projects including a signal generator with 50ohm output for use in the lab.
Crystal Ladder Filter
Power supplies
DSP audio DNR with speaker
Audio filter using LTC1060
QRP 5watt amp
30 Watt amp

100 Watt amp
     Wire Dipole, windom
     Whip active receiving antenna
     Window feed-thru construction
     Grounding system(s)
     Antenna accessories
     Center and end insulator
     D104 modified for modern day transceivers
     D104 with speech processing inside base
     MH-31 mic; increased sensitivity with EM172
Battery Paks for Field Day QRP rigs, solar charger


My bench:

click for larger view

My shack:

click for larger view



Current Project:
Build the SS-40 40m receiver kit from the 4SQRP group and then add to and modify to produce a receiver with sensitivity, selectivity and stability.

Sensitivity - the SS-40 already has a MDS of -134dBm, as sensitive as most modern high-dollar rigs.

Selectivity - Hi-Per-Mite CW filter provides 200Hz bandwidth without ringing

Stability - the N3ZI DDS provides crystal stability along with a digital display

Today, January 16, 2013 I start assembling the SS-40 kit. I will use the provided instruction manual along with illustrated instructions by KC5WA (You must scroll down to the bottom of the newletter. I will eventually have a complete QRP rig using this receiver, the Magic Box, the NS-40 transmitter, and the Hi-Per-Mite audio filter.

Jan 18 - assembly is going perfectly so far.

Hint: Download the parts list from Rich Fowler K8MEG - makes identifying the parts much easier. For more pictures see the instructions by KC5WA (ya have to scroll way down the page to see them.)

Jan 19 - progress on SS-40 rcvr. Power supply section works and the audio section works. Just finished going backward through the circuits now including the product detector and all are working.

Jan 20 - added crystal filter section and post mixer amp. So far so good.Post mier finished and testing done according to the instructions with the results exactly as stated. Starting on the VXO circuit now which will be partly replaced by a DDS LO later on.

Oh no! a snag. was going to see the VXO output on my 40+ yr old scope and it's not working. . .and, don't have a RF Probe handy.

Well, I ordered a new Tektronix scope. will be here Tues. Mixer stage finished and ran test descibed in instractions and heard static and some local RF intererence. I hope that's a good sign.

I'm trying now to finish tonight. If you're wondering how long this project should take it would have taken me just one day if I had cut out the naps.

It works !!! Copying CW signals on 40m.

Next step. Put it in an enclosure.

Finished SS-40:



Plan a QRP Constructioin Project (Dave Metz, WA0AUQ) Borrowed from the Flying Pigs QRP Club

  • Decide if its important to do
  • Study the prior work of others
  • Make a preliminary simple design, document everything you do!
  • Round up your parts
  • Build in modules! Make one module at a time work.
  • Don't get discouraged, ask questions, finish what you start

References from various publications - - - - click here



Here's a simple starter project

Building a simple DC receiver:

  1. Build in modular fashion (using Manhattan style + some modified pcbs from (Parts&Kits) a simple 40m NE602 direct-conversion receiver. Will use a simple VXO (variable crystal oscillator)circuit for LO (local oscillator). The receiver will be enclosed in a tin peanut-brittle candy box from Russell-Stover with old knobs purchased on eBay. LM386 audio amp module is from Electronics Salon (eBay store).
  2. Illustrations are here #HB1. . . candy box, knobs, schematic, example of manhattan style breadboarding construction, NE602 Mixer board, 10K 10turn pot for tuning, a variable capacitor for input tuning, and LM386 audio amp.
  3. To save time I will modify some ready-made PCBs from http://partsandkits.com/store2.php
  4. More illustrations are here #HB2. . . 1st mixer pcb, front-end transformer, osc inductor, pcb layout, parts for front-end,
  5. Add LM386 audio amp to finish receiver.
  6. More illustrations are here #HB3. . . finished receiver pcb, final receiver view, audio clip of working receiver

Now we start the improvements:

  1. Replace VXO with VFO circuit as shown in Experimental Methods in RF Design - ARRL
  2. Illustrations are here . . . schematic from book, our modified schematic
  3. Replace simple front-end with double tuned LC BPF (band-pass filter)
  4. Add LCD/Counter module from N3ZI to LO on NE602 (may need buffer)
  5. Turn into superhet by placing crystal ladder filter in IF and  adding 2nd NE602 mixer-detector with VXO BFO. change to different LO freq to accomodate intermediate freq.
  6. Install in larger enclosure
  7. Improve audio by adding NE5532 limiter and CW filter.
  8. Improve noise reduction by adding DSP DVR module
  9. Add JFET circuits for transmit audio blanking for QSK
  10. Replace VXO LO with DDS2 along with LCD display
  11. Replace BPF ahead of 1st mixer with BPFs to cover more HF bands
  12. Add another mixer using xtal LO same freq as rcvr IF to yield transmitter freq same as rcvr. Must add BPF after this mixer. Still need to figure out RIT circuit for this receiver.