Tuesday, September 22, 2009

E-H Antenna

Because of my limited space for antennas, I decided to do a little experimenting with an E-H Antenna. An E-H Antenna is a tiny HF and MW antenna. Originally designed for AM broadcast stations, these antennas supposedly operate with extremely high efficiency, but come in a very small package.

More information at http://www.eh-antenna.com/

I built one for the 30 meter band. The antenna is about 2 feet long, and have the antenna resonant close to the 30 meter band. According to my SWR meter, it currently runs about a 2:1 SWR on 10.139 MHz. I could get the swr down even lower by adjusting the matching coils. I did a rough tuning on mine, and got it close enough for now.

I've read mixed reports by hams who have built these antennas for themselves. Many say they dont work. Here is what I've found so far:

On receive, it seems to pick up a fair amount of noise, but that could be due to antenna placement. I dont have the antenna up very high, only about 10 feet.
On transmit, it appears to do fairly well, even at this height. Signal reports are about even using WSPR. I chose WSPR as an antenna testing mode because every station "advertises" their transmit power, so I can compare transmit vs receive efficiency easily. There is a difference, as my untuned 20 meter hamstick (going thru a tuner in the shack) consistently runs about 10 dB weaker on transmit than in my receiver.

Although this is not paint a complete picture, it does tell me that it works equally well, (or equally poor) between receive and transmit. When I am able to test the antenna when its up a bit higher, I'll be able to make better comparisons.

Watch for me on the 30 meter WSPR freq. I'll be beaconing using this antenna for awhile.

Sunday, September 20, 2009

10 GHz Mountaintop Operations

Saturday, Sept. 19 (2009) was the first time I have operated from a mountaintop on 10 GHz, and I'd like to share some observations from this particular trip. Because this was the first time I have operated from this location, Blue Knob, PA EN00rg, I'd like to tell you what I learned from this trip.

Mountaintop operations such as this tests the capability of your equipment beyond what I have experienced along the lake. Things such as receive sensitivity, pointing accuracy, etc are tested. On this trip, most of the signals are much weaker then what I experienced on Lake Erie.

One thing that was noticed readily on this trip, although our most experienced operator on site, KB8VAO said that this was a fluke, but the 2 meter band conditions were far better than the conditions on 10 GHz. Typically, signals on 10 GHz are much stronger than on 2 meters. Now I have noticed this up on the lake, but I figured this was caused by the duct over the lake being much smaller, and not able to support 2 meters. However, on the mountain, stations in New England were extremely strong on 2 meters, but almost imperceptible on 10 GHz. Many stations had to be worked on CW because the signals were so light. Most of the contacts were a struggle, especially the ones over 100 km away.

Although band conditions were such that there was a 2 meter opening, and 10 GHz seemed flat in comparison, I still managed to break my old personal distance record and worked Vermont which was just under 600 KM away. It was hit and miss for awhile, signal was quite weak, and had to be done on CW. I think next trip, I'm going to bring some form of headphones. I have found that headphones will give you about a 10 dB advantage, at least for me when working extremely weak CW.

The next week or 2, I'm going to compile an equipment checklist, I forgot to bring my code key, and had to borrow one to make the contact.

I worked about a dozen stations total from the mountain, ranging from 60 KM to 600 KM.

Tuesday, September 8, 2009

PowerSDR-IQ with the SoftRock v9.0 Lite+USB Xtall

I've been running the Softrock Xtall+Lite v9.0 with the individual band pass filter boards for several months before I broke down and purchased the Electronically Switched Bandpass Filter about a month ago. Ever since I got it, I had problems getting PowerSDR to switch the filter automatically. I know the filter works because it works fine using Winrad. Today, I got powersdr-iq working with the filter using a fancy little trick that I discovered.

The first thing I did was to uninstall powersdr-iq. I went into windows explorer and deleted what was left in the installed folder. I then went and reinstalled powersdr-iq.

Now here is where it gets tricky. If there is a .dll file in the installed directory called "ExtIO_PMSDR.dll", rename it to something like "EXTIO_PMSDR1.dll". Then go and download ExtIO_Si570.dll and save it in your powersdr-iq folder. Rename the file to "ExtIO_PMSDR.dll". Run Powersdr-iq. Go to setup > General > USB and UNCHECK BOTH boxes under AVR. Then go to the ExtIO tab, under General and check "PM-SDR Enable". Click the "Toolbox" button. You will get another box pop up. If you have Winrad installed and working with the dll for the Softrock, this box will look familiar. If you need help with this box, here's what you need to do with it.

Under "BPF", check "Enable". Normally the info in the band boxes would have for Band 0 1.8 to 4 mhz. I built my BPF so that band 0 is 50 - 54 MHz, so I changed those numbers. I also changed Band 1 to 3 to 7 MHz. You may not have to do this, but by experimenting with the cutoff freq's for MY individual filter, I found these numbers to work best.

I have posted to the usergroups regarding this problem, but it sure seemed that I was the only one that had this problem. I find that hard to believe, but now that I have this new dll installed, I can fully customize the filters, and they switch just like in winrad, probably because its the same software snippet that Winrad uses!

If you have noticed this problem too, give this fix a try. At the very worst, you might need to uninstall psdr and start over. This is all experimental software, and I'm sure that if youre using this stuff, you've probably uninstalled and reinstalled more than once anyway. Its worth a try. Let me know if it works for you too.

Wednesday, September 2, 2009

1296 update

I had just finished rebuilding my 1296 rig and assembled the modules. I added a 3 pole bandpass filter between the transverter output and the 10 dB gain block that drives the 2 watt PA. When I initially tested, I wasnt getting any power out of the rig, so I proceeded to test for RF at each stage.

I was getting the usual milliwatt or two out of the transverter., but at the output of the filter, there was nothing. I retuned the filter for max output. I lost about 3 dB thru the filter.

After hooking up the low level amplifier, the measured output was about +8 dBm. A little lower than I expected, but it's enough to drive the 2 watt amplifier to a useable output level. A quick check at the 2 watt PA output indicated a healthy output. I then determined that I had the antenna relay hooked up backward, RX line going to the TX port, etc.

Once I got it all hooked up, there was an oscillation, which I cured by shielding the low level amplifier. The output is a little low, i think, but I still believe it is enough to so some good mountaintop work. I believe I can get a little more out of the transverter, however, so I'm sure I can get the power level up to where it should be. I guess the level to shoot for is +10 dBm out of the low level amplifier. So, it looks like I'm capable of getting on 1296 now.
FT-1900r Yahoo Group

Subscribe to ft-1900r

Powered by us.groups.yahoo.com