Amateur Radio - KI7V


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QRP Anyone?

These rigs were my introduction to operating QRP.  A co-worker told me about his QRP activities and sent me a number of web links for some of the kit suppliers.  I thought that it might be fun and you can put something together inexpensively.  I purchased a rockmite-40 QRP transceiver board ($25.00) from Small Wonder Labs.  This transceiver is definitely QRP (Reduced Power) with an output rating of only 500 mW.  I purchased an aluminum chassis to house the rock-mite 40 in from Fry's Electronics.  The box is made by Context Engineering - part number 2506H-4.3N with the following dimensions in inches:
4.3L x 2.61W x1.54H.  This page will be updated as I build the unit and see how it works.  

Well, I received the RM-40 kit and got it put together.  It turned out pretty nice with the case shown here.  First evening that I got it up and running, I worked two California stations from my QTH here in Phoenix-AZ.  Not bad for 500 milli-watts!!!  Overall, the kit was pretty easy to assemble with the exception of the one surface mount device.  I would recommend gluing the device down to the board prior to soldering.  The rig didn't work when I first powered it up.  The problem turned out to be pin-8 on the surface mount IC wasn't soldered to the pad completely.  There was no audio until I pushed on pin-8 with my volt-meter probe and it came to life.  A little extra solder on the surface mount IC pins and we're in QRP land!

I would certainly recommend the Context Engineering case for this kit.  It has printed circuit board guides to slide in the board.  The Rock-Mite PCB was just about 1/32 of an inch to large to fit in the guiding slots.  I used a file to take off just enough until it slid into the guides.  There are some pads that are pretty close to the case, however there is enough clearance to prevent anything from shorting out.

In the first 4 days using the rock-mite at 500 mW I worked 6 states AZ, CA, ID(737 Miles, RST 579!), WA, OR and ND).  North Dakota being the longest DX (1157 Miles, RST 599!).  This is proof that amateur radio can be very inexpensive with the fun factor very high.  This is an impressive little rig and I then ordered the 20 meter version.  

I also built the RockMite Audio Filter by KD1JV (  The audio filter works great for the rock-mite and is a worthwhile addition.  A switch can be hooked up to switch between two filtering widths.  It also includes an audio amplifier that drives a set of head phones very well.  You will want to add a volume control if you add the KD1JV Rock-Mite Audio filter.  The filter kit has all surface mount components and is a little challenging to build, but with a magnifying glass and following the suggestions that come with the kit, it is not that difficult.  My 20 Meter contacts haven't been up to par with the RM-40 with my R7 antenna.  I'm trying the RM-20 with a wire dipole to see if I get better results.

Once it is all built, you have a complete 20 or 40 meter CW transceiver with wide and narrow audio filtering.  All is needed is a simple dipole or long wire and a 9 volt battery, headphones and a paddle.  Shown here is the front panel of my RM-20.  The switch on the left is the power switch.  The smaller toggle switch in the middle switches between wide and narrow audio filtering.  I made the volume control knob, by cutting a metal phone jack to the length of the volume control shaft.  I then drilled and tapped a hole in the volume control for a set screw to hold it on.  I don't know which is more fun, building it or operating it.  There are many other examples of built rock-mites at the "Rock-Mite Files".

The photo below is the inside of my RM-20.  The KD1JV Rock-Mite Audio filter board is on the bottom and partially underneath of the RM-20 transceiver board.  As mentioned above the RM-20 board slides into the machined guide rails in the side of the case.  I put tape on the bottom of the KD1JV audio filter board to ensure nothing shorts out on the bottom.  If you've never built any kits before, you should try one of these.  To me, this is more of what HAM radio is about.  After building both a RM-20 and RM-40 and trying QRP operation, I then purchased the Elecraft K2. 

73's es cu on the QRP frequencies: 7.040, 14.060.  de KI7V