The MP20 is the club project of the Flying Pigs QRP Club. It was designed by Dieter "Diz" Gentzow, W8DIZ. It is intended to be an all band HF transceiver. It uses plug-in band modules much like the Ten-Tec Scout. The basic parts kit only includes parts for 20 meters, hence the name MP20 (MultiPig 20). The rig is made up of several different modules. They are: Frequency Counter (also used as the display for the rig), phase locked loop, transceiver board, crystal filter and 20 meter band module in that order. The whole rig is intended to be built using "ugly" style construction. There are about 20 people partcipating in the project. 9 of the rigs had been completed at the time of this website's creation. I was not originally going to build the MP20, because I didn't have enough money for parts. Well, one day, Bruce, KG4DZU offered his MP20 parts for sale, because he didn't have time to build the rig. He sold the parts to me at his cost (thanks Bruce!). I began building as soon as I received the parts.

The first part of the project is the frequency counter, which is also used as a display for the rig. I put the frequency counter LCD on a socket so I could remove it and use it for other projects. I spent about 2 or 3 hours total assembling the frequency counter, and it worked the first try (well almost, I had a dirty socket pin). The frequency counter used in the MP20 is based on an AADE frequency counter. It includes an adjustable offset to compensate for the IF frequency. A picture of my frequency counter is below (click to enlarge):

The next stage of the MP20 is the phase locked loop (PLL). The PLL generates the frequency mixed with the IF frequency to tune the entire HF band. More information on the MP20's PLL is on the MP20 website at: www.fpqrp.com/pigg20 The PLL is built in four mini stages. The first stage involves mounting the BCD switches that are used to control the PLL. This is actually the only lesson so far that I've messed up. I wired the switches in reverse order. That means that I have to set the numbers backwards, for example, to get an output frequency of 14.060 MHz, the switches must be set 40113, but because mine are backwards, I have to set 31104. This problem made me think my PLL wasn't working, but with Diz's help, I was able to track the problem down, and after reversing the setting, the PLL came right up and worked.

The second stage is the reference oscillator, which generates the signal that the PLL uses to "lock" the output frequency. The reference oscillator was quite easy, and only took me about 45 minutes to assemble. Here is a picture of the reference oscillator section of the PLL board:

The next stage is the error amplifier. The error amplifier is packed into a fairly small space, so I had to use needle-nose pliers a lot, but otherwise, it wasn't very difficult. Here is a picture of the error amp section of the PLL:

The last part of the PLL is also the hardest. It is the voltage controlled oscillator (VCO). A picture of the VCO, along with the completed PLL board (except for the missing varicap, which I'm still waiting for), is below:

The next part of the MP20 is the transceiver board. The transceiver board includes the AGC circuitry, the crystal IF filter, the audio amplifier, and all the mixers that are part of the rig. I'm almost done with the transceiver board, but I haven't been able to use the camera for a while. A picture of the transceiver with just the mixers, the terminal strip used to make connections to the rest of the rig, and some associated circuitry is below. More pictures to come soon.

This page was last updated on May 18, 2001
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