October 2016 – K7OJL Ham Radio Blog

K9YA Telegraph

The Robert E. Heytow Memorial Radio Club publishes a “general interest amateur radio eZine” called the “K9YA Telegraph“. I ran across it a little over two years ago, subscribed, and have enjoyed every issue since then, as well as have read several previous issues from the archive.

This is a subscription electronic magazine. The subscription is free. The current issue had some very interesting follow-on information about the National Air Race in 1929 and amateur radio involvement along with links to documentaries on the air race. The magazine comes as a downloadable PDF and usually is eight pages long.

The magazine has been serializing a story about amateur radio operators called “Rose”. Part fifteen was included in the latest issue. It is a well-written, quite engaging story and I usually read the next installment as soon as the magazine is downloadable.

Check it out at http://www.k9ya.org/index.php.

QRP Receiver … Ready for Testing!

The Rexwood 1000 QRP receiver was a straight-forward build. Two testing stages were part of the build. I had the first two stages completed several weeks ago, but needed the Tuna Power System (TPS) to provide power. I put the receiver aside and completed the TPS (see QRP Power Supply Completed and Tested).

I finished the rest of the receiver this afternoon. It is putting out sound. I need to put up some kind of an antenna to see if I can hear anything in the narrow range the receiver can tune: 7.030 and 7.0475 mHz +- a few kHz.

I’ve hooked the TPS up to the receiver and both seem to be working as advertised. Next I’ll start on the Pixie transceiver so perhaps it can provide a signal that the receiver can pick up to verify that it’s actually receiving something.

QRP Power Supply Completed and Tested

The second build of the Tuna Power System (TPS) is completed. Earlier I built one, tried to test it, but failed (see Letting Out the Magic Smoke). I took a lot more time and carefully built the second try. I was quite successful this time.

In order to properly test the system, I needed a bench power supply. One that would allow me to set a specific voltage and a specific amperage, that would run with either constant voltage or constant amperage, that had short protection, and that I could afford. After listening to a HamRadio360 podcast having to do with workbench tools, I had an idea of what I wanted to buy. I found a Dr. Meter bench power supply on Amazon.com, ordered it, and really like the device. I definitely didn’t want to let out the magic smoke and ruin another device.

I first used the VOM to check continuity and resistance values at various places according to the circuit diagram. I got all of the expected readings. I then inserted the IC chip, connected up the Dr. Meter power supply setting the output voltage to 20 volts and the maximum amperage to 500 milliamps and turned on the Dr. Meter output. I was getting only about 5 volts into the TPS at a constant current setting. I upped the amperage to 1 amp and tried again. This time I got 20v input to the device, no smoke or shorts, and voila! 13.8 volts at the appropriate outputs and 5 volts ad the appropriate jacks. The IC stayed nice and cool.

Next step was to hook up the 20v wall wart power supply I picked up at a thrift store. This was a power supply for a printer and advertised 20v output at 4.5 amps. Again, the VOM read 20v input and 13.8 volts output at all the right places. And the IC stayed cool.

We’re ready to move onto the next two devices. I’ve got a Rexwood 1000 Receiver kit from QRPME.com. I’ve got that kit started and am ready to test the audio output section.

I also have a Pixie 40m Transceiver kit that I bought from Banggood.com for $3.82. This one comes with a PC board and components. No instructions or other information. There are some pretty good pictures on the Banggood.com site, so that will help with the build process. Capacitors are the most difficult for me to read, even with a 20x magnifying glass. To help with that I bought a capacitance / inductance meter also from Banggood.com. This wasn’t a kit, so I don’t have to put it to use before using it to figure out what the values are of each of the capacitors in the Pixie kit. I can read the resistors with my VOM.

Onto something that should receive RF and transmit as well as receive!

40-Meter Dipole … Fail!

At our previous address I built a 40 meter dipole that worked somewhat well. I was able to make a few contacts even though the band conditions over the summer were very poor. At least the afternoon Hawaii net on 40 meters was workable. The antenna apex was about 25′ above the ground and the legs in a sloping inverted V configuration coming down to about 10′ above the ground. The antenna was oriented northwest to southeast which would put the major lobes towards North America and towards New Zealand and Australia. The SWR measured between 1.3:1 to 1.5:1 across the 40-meter band. It also had similar SWR on 15-meters.

Then came the requirement to move. I tried to put the same antenna up here. Because of limited places to guy the painter pole holding the apex of the antenna, I was only able to get it about 18′ above the ground. The legs were again in an inverted V configuration, but also angled away from the antenna. Rather than having a 180° spread, the angle was closer to 150° on one side and 210° on the other. The antenna also was in an east/west orientation, meaning the main lobes (what there was of them) went north and south. Further, at that height, the takeoff angle was no lower than 60° making the antenna at best NVIS. The legs were attached to an 8′ 2×2 board velcro’d to the fence and had to go through quite dense foliage. I had 50′ of Radio Shack RG-8u coax to go from my Yeasu FT-897D to a 1:1 current balun at the apex of the antenna, meaning that about 30′ of coax was coiled on the floor behind the radio.

The SWR was horrible; resonance was 7.045 Mhz with an SWR of 7.3:1, too high for the built-in tuner to accommodate. I have an MFJ-971 portable tuner that I bought to use with my (still in the box, not yet powered up) Xiegu X1M Pro QRP transceiver. With that I was able to bring the SWR into a more reasonable range, but the SWR fluctuated across a very wide range from the wind in the foliage. Further, the coil of coax was also acting as an inductor with a lot of capacitance further screwing up the signal. I then picked up at 20′ piece of Radio Shack RG-8u coax, that improved the power output considerably, but the FT-897D did not like the SWR fluctuation at all. The antenna was simply non-functional. Down it came.

As an aside, we have an excellent Radio Shack about a half-hour away to the northwest in Hale’ewa. This is one of about ten still open stores in Oahu, but the only one that actually stocks parts. All the other stores are concentrating on selling cell phones and audio cables with literally no other stock. The store in Hale’ewa, however, keeps a fully stocked parts section. I love that store!

I have a Buddipole antenna system, the “long” version. It works very well, but takes me a half hour to get set up, guyed down, and tuned. It’s not at all advisable to leave this antenna up in the Hawaiian salt air / volcano ash / frequent rain showers weather. That was the reason for thinking about putting up a 40-meter dipole so when I had a few minutes I could sit down at the radio and see what was happening. As we move into “winter” (a strange term in Hawaii), band conditions will favor 40 and 80 meters.

I may still try to find a way to get a north/south orientation and trim that 40-meter dipole down into a 20-meter configuration. A 20-meter dipole is quite a bit shorter … we’ll see. We’re only here in Hawaii for 4 more months and then will be moving back stateside.