Sunday, April 17, 2016

CR-1A software Defined Radio


I was listening to shortwave a few weeks ago. I was a tuned to a US station playing some interesting music and the announcer did a commercial on the Commradio CR-1A. It is an SDR radio that covers MW, HF VHF and UHF. I went to the website and took a look. It is a small little radio with two knobs and six pushbuttons. Since it has been nearly two decades since I have purchased a new shortwave, I decided it was time to do so again. Not that my previous shortwave needed replacing, but this one will fill a niche that my other radios cannot. This one is small, portable and battery powered. You can select either shortwave banding or amateur banding. I listen mostly at night and the controls are very simple and easy to master. With six pushbuttons, the functions are easily memorized, nice when listening in the dark! So far, besides the usual stations that are easy like the US religious stations and Radio Havana, I have heard Radio New Zealand, Radio Australia, Voice of Korea in Pyongyang, BBC and Romanian Radio. Not too shabby for a little shortwave radio

Take a peek and the weblink below, the radio has a load of nice features.
Bob

Friday, July 5, 2013

Radio Dead Zone


The picture below is a screen capture of dxmaps.com, looking at 20 meters north America. I have long held the belief that the propagation here, in a word, stinks. I have been looking at maps like this for years, but the other day I saw this one which is especially pronounced in the difference between the northern part of the United States and the southern portion of the country.

Sadly, I have even pondered running QRO to try and overcome poor propagation. But, some afternoons or evenings, I tune across 20 meters and do not find but one or two signals. So even with some power it would still be tough to get out. Too bad I was not an active ham back in the 80's when (as the old timers say) You could load up a wet noodle and work the world.
72,
Bob 

Saturday, May 25, 2013

Latest EFHW antenna


It has been too long since I have posted. A little busy with life and work, but that is no excuse. I do have the latest incarnation of my favorite antenna, the end fed half wave done and ready to put on the air. Had I actually had my brain in gear in the first place, this would have been done a lot sooner. As it was I did the brute force approach, which was cut a separate wire for each band. In retrospect, this was idiotic. The much better way to do it was done by Ed WA3WSJ when he made his Iditarod Dipole http://wa3wsj.homestead.com/iditarod_mini__dipole.pdf  Ed uses snap swivels and spade lugs to connect more wire sections to the antenna to change the dipole frequency.
DING DING... Pay attention Bob!

The main reason I hate dipoles and really like EFHW's are that dipoles need to be pulled up on the center, and each end. Don't get me wrong, the dipole is a superb antenna, I just hate having to raise the dang thing. The EFHW works well here in Washington State as we have an abundance of trees. I connect a quarter inch thick steel washer to end of the wire, swing it around three times for luck and sail the wire over a branch. The antenna is up in seconds.

As you recall, the counterpoise for the EFHW is .05 wavelength. So, for 20 meters, the antenna wire is 33 feet, the counterpoise is 3.3 ft. Easy math! At this point I will refer you to an earlier post for how I make my EFHW tuner.  http://eggsandhamradio.blogspot.com/2012/06/end-fed-half-wave-antenna.html

Here is the antenna wound around some corrugated plastic, which is my favorite material for lots of things in the shack. In the picture also is one of my EFHW tuners.


When I measured out the wire, I used 468/Freq to get the half wavelength. From there you need an antenna analyzer to nibble the wire down to tune where you want best SWR in the band.

What I did for my antenna is as follows:
15 meters was 22 ft of wire and 2.5 feet of counterpoise
To add 17 meters, I connect roughly 3 feet more to the 15 meter antenna, same counterpoise.
To add 20 meters, I connect roughly 8 more feet of wire to the 15/17 meter antenna, same 2.5 foot counterpoise.

I somehow messed up cutting the wire and was a tad short so the 20 meter wire resonated in the SSB portion of the band. I then cut a 15 inch chunk of wire to add in for the CW portion of 20 meters, removed for the SSB portion. This mistake actually now seems to have made a better antenna, I now have an excellent match in both portions of 20 where I like to operate.

73, Bob

Sunday, December 16, 2012

Analog Signal Processing


In the November issue of CQ magazine, there was a great article on an interesting kit. The kit is a regenerative audio filter. The filter, according to the designer, Phil Anderson W0XI, removes or scrubs galactic and man made noise from the audio, leaving only the CW note. At first I thought, interesting, but really??

First, some background. Band noise on some receivers can really get bad, not only bad but teeth grinding, chalkboard scraping annoying. I got rid of a transceiver which was nearly unusable on 40 meters. The noise blanker did nothing to touch the noise. Currently, I am now using a Yaesu FT-817ND which a month or so ago, I was in the backyard with a wire in a tree checking into the NAQCC Rocky Mountain QRS net. It was a rugged contact. The noise level that day was really bad. It started me thinking about different options to deal with the noise level. My two choices were the NEQRP SCAF filter (Temporarily out of stock) or the W4RT installed BHI DSP filter. The SCAF is about $30-35, and the BHI is $169 installed. I was pondering the two when I bought the November CQ magazine to read a review on the Elecraft KX3 and found the article on the CW regenerative filter by Midnight Science.


Meanwhile....

I walked into my wife's sewing room who looked at me and said: “You look bored”. I replied, “I am”. She then said, “You need a kit” First rule of marriage, do not argue with a woman, especially when she is right. Between the CQ article and the need to melt solder, I ordered the regen kit. I went the full meal deal and got the case along with it. It is a basic through hole component kit with 5 chips, resistors, capacitors, all the hardware and a voltage regulator. It is a high quality kit with everything included and integrates nicely in the case.

Now the performance, I was blown away by the ability of this filter to remove noise from a signal. After completing the kit, a random wire was connected to my FT-817 and the filter switched in. You have the option of bypassing the filter, if you wish, by pressing a button. I was amazed at how much static and junk was removed from the band noise. Indoors at the time, when I switched on a fluorescent light, I got a load of extra noise. When the filter was switched in, the lamp noise, along with most of the static, was just......GONE. It was flat amazing. I went to 20 meters and found some CW signals to tune. When you cross the designed frequency (You have the choice of building for 500, 600 or 700 Hz) the signal noticeably peaks. The noise is gone and stronger signals are a pleasure to listen to. I then tuned to a weak signal which was going in and out of the noise. I brought up the regeneration setting until the filter broke into oscillation and then backed it off a skosh. The signal had a slightly hollow, slight echo quality to it at the sweet spot of regeneration. I switched the filter out and listened until the CW started into a deep fade, I then immediately switched in the filter and the signal popped into my headphones. From completely in the noise to easily copyable, the filter is flat amazing. Even if you are not listening to a weak signal, back off the regeneration and use the filter just to clean out the noise, you can listen for longer periods without fatigue. This is one of the best purchases I have made.

72,

Bob

Saturday, October 27, 2012

USBlink Digital Interface

One of my favorite modes is PSK31. I had seen the USBlink project on the fine website of Julian, G4ILO, and the project looked downright useful.
Julian used a cheap USB sound card dongle. Mine cost under 5 dollars US including shipping. The rest of the USBlink is the Skip Teller digital interface circuit for PTT to the transceiver. There are several things I like about this interface project. First is the USB cable. I built the original Skip Teller KH6TY interface from the June 2009 issue of QST. I like the function of the interface, but not the two audio cables hanging out. The USB cable is a nice alternative, no fumbling with which cable is mic and which is phones, just plug in the USB. I built the interface with a six pin din connector. The main reason for the six pin din was my FT817 and Icom IC703 have that connector for digital connections. Interestingly enough, both radios have the same pinout. I can make one cable with straight through connections and not worry which end is plugged into the radio or the interface.
I made only two departures from the USBlink original. First was the the USB connection, I wanted the B type USB connector so I could use a standard B to A cable which you can steal off your USB printer in a pinch. I picked up a female B and a female A connector and wired them together. The dongle plugs into the A connector and the external USB cable plugs into the B connector. The second difference was the green LED. Just like Julian did, I clipped off the green LED from the dongle and soldered wires to a larger LED mounted on the case. I noticed however, the green LED was much brighter than the red Transmit LED. I wanted both LEDs to be about the same intensity so I put a 1K resistor in series with it and now they are visually comparable.
This project is nice, compact, and inexpensive. I got the box and components from my junk box. The purchases were the USB connectors, the sound card dongle and the cable and din connectors. The entire project cost $15 tops. I was in need of a nice 4 conductor cable for the project so I went to RE-PC in Seattle and in the used cable area, got a 15 foot USB cable for one dollar. I clipped the ends off and have enough cable to make five, three foot cables. I don't have that many radio's but I'm sure the cable will come in handy for other projects.
72,
Bob, AD7BP

Sunday, September 16, 2012

Low Noise End Fed Half Wave Antenna


This afternoon I grabbed my ATS-4 to hop on 20 meters and do some operating. My ATS-4 had 5-6 bars lit on the S meter display, which translates to NOISY, but not sure what the corresponding S reading is. I wish I had my FT-817 so I could have looked at a regular S meter. I tuned around and heard some signals, some were copyable, but it was just too noisy to really operate. This is obviously not the first time the noise was just too high to operate. I was, by the way, in the backyard with one of my end fed wires in a tree. I pulled the wire out of the tree and strung it across the ground and the S indication dropped from 5-6 bars down to 1-2 bars!!! So, I decided to FINALLY change one of my tuners to allow switching between two different wires. 
Most of my tuners are very small and compact to throw it in a pack and go into the woods. I have one large tuner with a real capacitor and added a switch and a second terminal for the “low noise” wire which lays across the ground. I guess the only downside to this arrangement is having to flip the switch going between transmit and receive. But, if I can knock down the noise by two thirds, it is more than worth the hassle. Since I mostly operate on 20 meters, I only have to cut a single wire.

72,
Bob, AD7BP

Sunday, September 2, 2012

Summer Tomatoes


It is about time I made another food post, seems that ham radio is taking more of the bandwidth than food.
I love summer, my favorite part is the crop of produce which is available. My two favorites are fresh figs, which are past and gone. They were delicious though! And tomatoes. I was at the local Costco and there was a 25 pound case of California Roma tomatoes calling my name.
We like a simple pasta sauce of olive oil, garlic, basil and tomatoes. Being a fan of putanesca, I toss in capers and Greek olives with my serving. With sauce in mind, it took me nearly 3 ½ hours to cut up the tomatoes. The cut tomatoes were put into a 2 cup measure and poured into a food storage bag for freezing.
25 pounds of tomatoes yielded about 25 bags of tomatoes for the freezer. At $11.65 for the case, the tomatoes for each meal is roughly 47 cents. Considering one pasta meal a week, this one purchase gives 6 months of nice tomatoes for pasta night. I did have a thought. We normally grow basil to make pesto to freeze. Since we are stocked in the pesto department, no basil was planted. Major mistake! Though I like the flavor of dried basil, 4 or 5 leaves roughly torn and tossed into the tomato sauce right before serving gives the sauce a bright, fresh flavor. That mistake will not happen next summer.

Life is way too short not to make a meal which puts a smile on your face. Cooking need not be complex to be satisfying. Make something good this week!
Bob