My Low-power Morse code radios

One of the enjoyable aspects of the amateur radio hobby is that, with an amateur radio operator’s license, you can build your own equipment from scratch.  In fact, back in simpler times most equipment was either homemade or was modified from old commercial or military equipment.  Now that 99.9 percent of electronic devices use integrated circuits, micro-computers, transistors, and tiny parts, and because it’s often difficult to find suppliers who sell small quantities — as in one or two of an item — most amateur radio equipment is commercially made.  However, there are several individuals and companies that still produce kits and sell individual parts for the experimenter.

Another fun aspect of amateur radio is that not a lot of power is required to communicate with other stations.  While most amateur radio equipment operates at around the 100-watt level — and amateur radio operators can run as much as 1,000 watts — a lot of amateur radio operators enjoy using low and very-low power equipment.

This is a long story — I’ll keep it short.  Originally all amateur radio operation used Morse code and, because Morse requires that every word be spelled out, a system of abbreviations was developed.  Some of these abbreviations are the “Q” signals — for example — QTH means “location.”  If you send QTH?, that’s the same as aksing “What is your location.”  If you send QTH New York, that means “My location is New York.”  The Q signal QRP means “reduce power” — and over the years the term QRP has come to mean low power operation.  Generally, if a piece of equipment is described as a QRP rig, that means it runs 5 watts of power or less.

Currently I have six small QRP transceivers that operate on CW — Morse code; I built each of these from kits that I purchased from the folks who designed them.  My current QRP rigs are:

  •  SW+40 : 40-meter band; 1.5 watt CW transceiver; superhet receiver.
  •  SW-80:  80-meter band; 1.5 watt CW transceiver; superhet receiver.
  •  SW-20:  20-meter band; 1.5 watt CW transceiver; superhet receiver.
  • S&S Engineering ARK-4:  40-meter band; 5-watt CW transceiver with built-in keyer.  (An EXCELLENT rig, no longer available as of December 2008.)
  •  RockMite 40 and RockMite 20:  40-meters, or, 20-meters; CW; 400 milliwatts — less than1/2 watt; fits into an Altoids box.
  •  The FreqMite, a PIC-based frequency counter and readout from Small Wonder Labs.

SW+40 from Small Wonder Labs

Go to this page to see my experience with the SW-40+ from Small Wonder Labs — an EXCELLENT RIG!!!

Small Wonder Labs Update

In November 2013, Dave Benson shut down Small Wonder Labs.  As he explained so well on his website, Dave had been designing and selling QRP rigs since 1996, then, in 2013, he decided there was more to life than putting parts in little plastic bags.  Dave’s website will shut down in November 2014.

Rex Harper, W1REX, has taken over producing and selling a version of the Small Wonder Labs Rockmite, which Rex calls the Rockmite ][ — it’s on his website at QPRme.com.  Here is a link to his Rockmite][  page.  Rex has a lot of other QRP rigs, accessories, and parts available on QRPme.com.  Rex is NOT producing the SW-80, -40, -30, -20 rigs — only the Rockmite ][.

S&S Engineering QRP Rigs

Previously, I owned three QRP rigs that I built from kits manufactured by S&S Engineering.  I don’t know the history or current situation of S&S; I encountered them at a hamfest in the Washington, DC, area in the mid-1990’s and, over the course of a year, I bought and built two of their rigs:  ARK-4 40-meter CW tranceiver (5-watts), and, TAC-1 80-meter CW transceiver (4-watts).  In May 2010 I purchased an S&S Engineering TAC-1 for 40-meters on eBay.

After a few months I realized I was not using these rigs, so, I sold two of them on eBay and kept the ARK-4.  According to the receipt stapled in the rear cover of the ARK-4 assembly and operations manual, I purchased it in September 1993.  I use it rarely, however, in late June 2017 I rearranged my station, got rid of some equipment that I never used, and put the ARK-4 on the operating desk where I can use it regularly.

The kits produced by S&S Engineering are EXCELLENT pieces of equipment.  The guy who designed these rigs is/was an engineer who designed military and commercial communications equipment and his kits were made to the same quality as military and commercial equipment — solid, top-quality components, very stable and reliable designs.  It’s a real shame that these kits are no longer available.

S&S Engineering TAC-1

I had two of these, one for 80-meters, one for 40 meters — sold them on eBay.  I built the 80-meter rig from a kit in 1994 and purchased the 40-meter rig on eBay in May 2010.

tac-1 on stool

  •  40-meters, synthesized; tuned by the TUNE knob in the top right corner.  Turn the knob to tune up/down in 1 KHz steps — push the knob in and the tuning switches to 100 Hz steps — push again to return to 1 KHz steps.
  •  7.000 – 7.199 MHz
  •  4 watts output
  •  Built-in keyer with adjustable speed and weight.  The keyer defaults to 12 WPM.  When the rig is turned on, the LCD display shows the keyer speed — 12 WPM — then shows the frequency.  On the rear of the rig is a small push button — push the button and the LCD display shows keyer speed — turn the TUNE knob to increase/decrease keying speed — push the button again to adjust keyer weight — push again to return to frequency display.
  •  Very sensitive and selective receiver
  •  Very good keying characteristics.
  •  The 80-meter TAC-1 is identical to the 40-meter version except for frequency coverage;  3500 – 3750 KHz.

S&S Engineering ARK-4

Here’s a picture of the rig.

ARK-4

  •  40-meters, synthesized; tuned by the push-buttons on the left.
  •  7.000 – 7.199 MHz
  •  5 watts output
  •  Built-in keyer
  •  Very sensitive and selective receiver
  •  Very good keying characteristics.
  •  The pushbutton tuning is a bit cumbersome — notice the frequency indicator, it’s now reading 7.041 — reading left to right:
    •   The 7 MHz is fixed.
    •   Next is a slide switch that selects one of two 100 KHz band segments — 7.000 to 7.099 or 7.100 to 7.199.
    •   Next are two pushbutton switches — pushbuttons are located above and below the numbers.  These select the 10 KHz and 1 KHz — pushing the button above the number decreases the frequency, the bottom button increases the frequency.
    •   The knob to the right of the pushbuttons is fine tuning and tunes between the 1 KHz points.

I purchased this kit from S&S Engineering in 1993 and am using it as of June 2017.

S&S Engineering ARK-20

I no longer have this rig — sold it on eBay

ARK 20 001

  • 20-meters, synthesized; tuned by the push-buttons on the upper right.
  •  14.000 – 14.500 MHz
  •  3-4 watts output
  •  The kit had a built-in keyer option but this rig does not have the keyer
  •  Very sensitive and selective receiver
  •  Very good keying characteristics.
  •  The pushbutton tuning is a bit cumbersome.  There are four pushbutton BCD switches.
    •   The 14 MHz is fixed.
    •   There are four digits, each with one button above and one button below the digit.  Pushing the button above the digit increases the frequency, the lower button decreases the frequency.
    •   Tuning step is 100 Hz.
    •   For example, if the digits read 1251, the, the frequency is 14.1251 MHz
    •     The RIT knob in the bottom right corner tunes the receiver between the 100 Hz points.

I purchased this kit from an individual on eHam classifieds in 2010.

From time to time S&S Engineering rigs show up for sale on eBay or in the eHam.net website classified ads.  The ARK-4 and ARK-20 sell for $150 – $200 and the TAC-40 and TAC-80 sell for $175 and up, usually around $225.

The Rock-Mite 40

This rig is another rig from Small Wonder Labs.  The Rock-Mite puts out less than 1/2 of a watt — about the power to light a flashlight bulb.  The RM operates on only two frequencies but comes in different models for different amateur bands; it transmits CW (Morse code) only.  The RM includes an electronic keyer.

I have built three Rock-Mite rigs.

  • Two are for the 40-meter amateur band (7.000 – 7.300 MHz).  One operates on 7030 KHz and the other is on 7040, plus or minus a bit.
  •  The third RockMite is for 20 meters (14.000 – 14.350 MHz); this one is on 14.030 MHz.
  •  Dave produces Rock-Mites for the 80, 40, 20, and 30 meter bands.

These rigs are VERY small — in fact, the rig was designed to fit in an Altoids box — here’s a photo of my Rock-Mite in an Altoids box.

rm-alt-1

 

On the left end of the box are, top to bottom:  Power input (requires 9-12 volts, DC); jack for the paddle that operates the keyer; and, jack for headphones.  On the right end of the box, top to bottom:  antenna connector; button switch that when pressed does several things — changes frequency, switches between paddle or straight key, or, changes speed of the internal keyer.  The RockMite keyer chip does not have memory — that is, you cannot load CW messages into the keyer as is common with electronic keyers.  There are a couple of places who sell replacements for the keyer chip that have message memories.

Because the Rock-Mite runs such a tiny amount of power, making contacts with it is a challenge because it’s signal is usually so weak that it is swamped by higher-powered stations.  My experience varies — sometimes I call and call and never get an answer and there have been times when I have called and was answered right away.  Still, operation with this low power takes a lot of patience.

Here are some Rock-Mite resources I have found helpful:

  •   Join the Yahoo Rock-Mite Group.
  •  The Rock-Mite Files — somewhat dated but lots of good info.
  •  How one person built his Rock-Mite.
  •  Here’s another Rock-Mite.
  •  And another.
  •  A very nice box in which to mount the Rock-Mite if you don’t want to use an Altoids tin.
  •  And here’s a keyer paddle just the right size for the Rock-Mite — built like a tank.  if you get this paddle, you should look at the base — the paddle is fine without the base but the base makes it really stable.  Here’s a photo of the miniature paddle mounted on the accessory weighted base:

Small Wonder Labs and Rockmite Update

In November 2013, Dave Benson shut down Small Wonder Labs.  As he explained so well on his website, Dave had been designing and selling QRP rigs since 1996, then, in 2013, he decided there was more to life than putting parts in little plastic bags.  Dave’s website will shut down in November 2014.

Rex Harper, W1REX, has taken over producing and selling a version of the Small Wonder Labs Rockmite, which Rex calls the Rockmite ][ — it’s on his website at QPRme.com.  Here is a link to his Rockmite][  page.  Rex has a lot of other QRP rigs, accessories, and parts available on QRPme.com.  Rex is NOT producing the SW-80, -40, -30, -20 rigs — only the Rockmite ][.