Folding Camper Design

I am working on a folding camper design and drew the basic design in SketchUp.

In order to visualize the interactions of the pieces better I made a balsa model since I am still learning SketchUp. The balsa model is not to scale but is allowing me to figure out how the walls will work in this design. The idea is to have it fold up into a flat package when not in use for easy storage and transport but provide a solid wall enclosure for camping.

Art Project - Moai

This is a paper model of a Moai statue, like the ones on Easter Island. It is simplified for easy construction. The intention is a make a 5-6 foot high concrete version for my friends ranch

40 Meter QRSS Beacon II

After monitoring the QRSS beacon for almost a week I noticed something interesting. I had been using Spectran by I2PHD to capture the beacon but have now switched to QRSS VD by AJ4VD which allows me to easily review many hours of collected traces. It seems just after sunrise when the building where the beacon is housed gets heated by the sun the beacon frequency raises by 10-20 Hz and stays there all day and then cools down at night. Click the image below for the details. This is about a one hour segment and starting at 8:40 AM this morning it starts to go up and stabilizes at 9:05 AM.

40 Meter QRSS Beacon

I have activated a 40 meter QRSS beacon at grid DM24.







This beacon is a retired kit I built a few years ago by Hans Summers G0UPL. It is setup to run off 12 volts and tapped directly to a battery array on solar installation in the Arizona desert. The antenna is a DX80 off center fed dipole with its vertex at 15 feet. The screen shot is the signal at my home QTH (DM03) approximately 300 miles from the beacon. So far it seems to appear about 15 minutes after sunrise and disappear about 45 after sunset.

Double Side Band (DSB) Generation III

I have now built the Si5351 clock generator, attenuators, and Arduino Uno in one metal box and the NE612 mixer in another. This shielding was required because the clock generator was so powerful it was getting into the measurement receiver by radiating it! Here are the tin boxes I used:







Here they are open:







The below image is a screen shot from the 817 Commander tool that has a scanner function which plots the s-meter values over the scanned frequencies. I was feeding the balanced modulator with the carrier and a 4 kHz audio tone. You can see the two side bands and the center carrier. The carrier is in fact below the side bands as I expected. Using my FT-817 as the measurement receiver and using the s-meter measurement method, I was able to confirm the suppressed carrier.
Based on the FT-817 S-meter calibration data I found  HERE this is ~ 27 db below the side bands and probably at least 30 db since the s-meter on the 817 is not linear. Next step is the RF amplifier stages to bring the level up to a couple of watts.

Double Side Band (DSB) Generation II

I made some progress with my NE612 DSB Generator. I built it up in a shielded box and I have observed at least a reduced carrier of 20 db below the side bands now. My problem was with my measurement receiver, it was receiving the radiated carrier! I also have attenuated the Si5351 oscillator separately and not in the same box and then injected it into the NE612. Note the 10 db pad. Next I will try a balancing pot across pins 1 and 2 with the wiper to ground. I should be able to get 30 db of reduced carrier with the NE612. The audio fidelity is very good and I believe this will be able to produce eDSB (Extended Double Side Band).

Double Side Band (DSB) Generation

In my quest for a simple QRP phone rig, I have been experimenting with Double Side Band (DSB) Generation. Using the Si5351 as a local oscillator I have tried both a high level mixer (passive) and a NE612 (active). Both of these produced DSB but with a carrier higher than expected. This was all done on a open breadboard so I believe I am getting carrier leakage. As you can see in in the HDSDR image below I have a very broad DSB signal.

The other test involved here is the fact that I was using my simple Direct Conversion (DC) receiver from my Prototype Radio experiments. A DC receiver normally can not receive a DSB single because of its wide bandwidth causing it to hear both side bands at once. However in the case above, I am feeding the audio from the DC receiver to  HDSDR on my PC. Using the left channel only since the DC receiver does not have a I/Q stereo output (see below the feature in HDSDR).

This method allows the use of a low frequency Intermediate Frequency (IF), in this case 10 kHz allowing the DC receiver with HDSDR to demodulate DSB by receiving either USB or LSB and even ECSS (the DSB feature in HDSDR).

There are other problems with this method like multiple images, however it allows very simple hardware to be used for rigs and I believe two simple DSB transceiver would be able to communicate with each other using this method.