Ham radio – Page 30 – AB4UG Radioblog

Playing with the antenna analyzer

Finally got around to playing with the antenna analyzer I picked up at the Atlanta Hamfest. Came with batteries installed and a wall wart so it was ready to go out of the box. First thing I tried out were the inductance and capacitance measurements. Grabbed random wire wound inductor out of the junk box and put it against the antenna connector.

13 μH at 7.06 MHz. A pretty decent amount of inductance. It’s got a lot of windings and came out of a dead laptop power supply I think. Next I put a random capacitor on it. Capacitance meter told me it was around 216 pF. At 7.06 MHz, the analyzer measured 177 pF. Not too far off and something that I might expect at high frequencies.

The analyzer will also measure the amount of coax loss at different frequencies. Put a 75′ length of RG-8X to see what I’d get. At 7.06 MHz, a respectable 0.3 dB loss. At 146 MHz, though, 2.8 dB. Will have to make sure to keep the coax relatively short for whatever VHF/UHF antenna I decide to build.

Measuring coax loss at VHF with the MFJ256B

Time to bring it in and try it out on the antenna. I know the antenna works really well on the 40m band, and the analyzer confirms it. SWR of 1.1 and 50Ω impedance at around 7.2 MHz, pretty much smack dab in the middle of the band. SWR ranges from 2.1 to 1.5 across the band.

Next I want to go through and record some more detailed measurements about the frequency performance of the antenna and maybe graph some things out. I’m sure that will look interesting.

I wonder what the analyzer will tell me about my HT antennas…Analyze ALL THE THINGS!

Barcamp session idea

There’s an idea for a BarcampCHS session brewing in my head. Something along the lines of open source software and amateur radio. There’s a fair bit of it out there, most of which is something I’m interested in learning more about (like GNURadio). What better way to make yourself learn about something than to try to give a presentation on it, right?

The idea isn’t very well formed yet and may or may not happen, but it’s there. I’ve got until November to figure it out. Plenty of time, right?

Field Day!

Another ARRL Field Day is upon us!

ARRL Field Day 2013 logo

Like last year, I’ll be helping out with the CARS Field Day activities over on the Yorktown. Now that I’ve got a little bit more radio experience under my belt, I’ll be able to help out more with the preparations and will enjoy playing with the radios more than last time.

In preparation for Field Day, I’ve been given the task of getting the club laptops ready: installing updates and performing maintenance, updating the logging software (N3FJP), and getting them networked together so that operators at each station can see what’s going on.

TARC will be having their Field Day activities up in Goose Creek at the Marguerite H. Brown Municipal Center.

If you’re in the vicinity of either one of these Field Day locations, stop by and check out the amateur radio operations!

Working on 6m

Well, not only does the radio tune the antenna on 6m/50 MHz, but the radio and antenna seem to work pretty decently.

Spent about 3 hours tuning around on 6m in the Central States VHF Society 6m Sprint contest last night in seek and pounce mode. Tallied up 10 contacts all from grid squares in the northeast plus one in Wisconson. Got some VA3/VE3 stations too. All of them were coming in pretty loud here. I came across several other stations that were just barely audible in the noise. I could hear something there, but not enough to try to work them. Most of the activity I heard was in the lower portion of the 50 MHz band, below 50.3 MHz. I went as high as 50.5 MHz, but didn’t go much higher.

A bit of Googling brought me to this ADIF mapping utility by K2DSL that puts my contacts onto a Google map based on the grid square. It’s kind of neat to see where the signals are coming from.

View Larger Map

I think I’ll add some kind of 6m antenna to the list of Things To Build for the summer. Will be interesting to see if I can make some more distant contacts with a dedicated antenna.

Trying out 6m

Coming up on Saturday is the Central States VHF Society Spring VHF/UHF Sprints. It’s a short 4 hour affair starting at 7PM and ending at 11PM (2300Z-0300Z).

After reading a copy of Six Meters: A Guide to the Magic Band that I found at a used book store, it seemed like it would be a pretty cool band to play on. I usually don’t hear much on 6m during my casual twiddling around on the radio dial. I really don’t know how the antenna performs on 6m aside from the fact that the radio seems to be able to tune it there. Hopefully this will be a chance to find out. Hopefully there will be some good propagation for me on Saturday.