Experimenting at 461 THz

I went on YouTube ( http://youtu.be/pvj3KDp8Ae8 ) and found a simple circuit that allows modulation of a pocket laser pointer.  These red, 650 nm devices (461 THz) can be AM modulated with an audio transformer that varies the intesity of the light.  The modulated signal can then be demodulated by a solar cell directly wired to earphones (where voltage is directly related to light intensity.)

I went to my local electronics store and got my parts.  The solar cell was $5 and the audio transformer was about $3.  Depending on the laser pointer, most are 4.5V, you will need a 4-cell battery holder (I used AA-sized) and jump out one of the slots.  My laser pointers are 3V so I opted for a 2-cell holder.  The AA cells are larger capacity than the button cell or AAA cells normally used to power these pointers, so should offer enhanced life per cell during use.

The trouble I am running into with this experiment is that the audio transformer has significant impedence on one side.  Depending on how you wire it, you are attenuating either the laser power or the input audio.  The spec is 72 ohms on the input coil and 0.62 ohms on the other coil.  If you choose to attenuate the laser, your range is greatly diminished (my lasers are rated at < 0.5 mW).  If you attenuate the audio, you need much more audio drive into the circuit. 

While driving the input is easy enough if you are using a music device such as an MP3 player, it is more difficult if you are using a microphone.  The solution will have to be another circuit with an audio amplifier to add to the audio I wish to drive the circuit.  Unfortunately, my initial experiment had insufficient drive to generate the necessary signal. 

So tomorrow it is back to the drawing board (and the reference books) to make myself an audio amplifier that hopefully can be rated at 3 V so that I don't need another set of batteries.

73

UDR56K-4 Digital Radio

Well I've been following this UDR56K-4 Radio since it was introduced at Dayton last year.  While it was promised for late last year, it is now expected to ship late this year.  Today they offered it up for pre-sale.  I ordered a pair of them for digital comms, including Winlink or D-star (DV and DD) on the 70 cm band. 

The price around $400, but I am guessing this will rise as they are running into cost over runs and the real inflation is there so if you want one at their pre-order prices, you had better order one soon.

Some background, and ordering information is available on their blog: http://nwdigitalradio.com/

73
N1ZZZ

Pactor in the Pacific

I was able to spend a bit of time on the radio during my last voyage. It was a new ship for me, and my third command. The ship is a container carrier named the CAPT STEVEN L BENNETT. She was ending her US Navy charter and I was tasked with bringing her to the shipyard and getting her ready for commercial service. I joined the ship in San Francisco, California and brought her to the yard in Singapore. This would be a voyage of at least four weeks so there would be plenty of time to get on the air. Since I was the captain, I had a nice office near a window just under the bridge. I was able to run coax and a remote tuner control cable out through a pre-existing hole near my porthole and up to the bridge rail. On the rail I mounted my Icom AH-4 remote tuner and ran about 10 meters of wire in a sloping configuration to the top of the INMARSAT dome mast on the starboard side of the ship. I was able to tune from 40 to 6 meters with this wire which was about 25 meters over the water. I grounded both the rig and the tuner directly to the ship's hull, which is about the best ground you can get. My rig consisted of my old standby mobile rig, the now aging Icom 706 MKIIg. I had a small switching power supply and for digital comms I had my Rigblaster NoMic for soundcard modes and my SCS DR-7800 P4 Dragon modem. The latter is THE box for Pactor, outperforming all comers in pactor comms. Most sailors tend to use Pactor solely for moving email over the Winlink 2000 system. I cannot deny that much of my Pactor time was spent moving email to my friends and family via this system. While the INMARSAT system was certainly faster and more reliable, I like using radio and enjoy moving the personal mail over this system. I was able to make links nearly every day first from US West coast stations and then Alaska, and finally China and Russia. I was able to make Pactor III links the entire time, and speedlevels ranged from SL 1 on the weak links to SL 6 when I was fairly close. I had only 1 SL 6 link when I used the PTC-IIe and that was from a very nearby station. With the Dragon, the average link was SL3 (1400 bps) with several miles of distance between myself and the shore station, with several links being SL5 or SL6 (about 3600 bps). The only time I had issues with WL2K was in the South China Sea. While there are several nearby shore stations, I had a devil of a time accessing them as soon as I entered the Sea. This continued all the way to Singapore. I did not only use the Dragon for email however. I was able to work US and Canadian stations on Pactor well West of the Hawaiian islands. I was impressed with the robust nature of pactor. Most of these links were Pactor 2, but I did have some Pactor I and Pactor QSO's as well. We did not tend to move files during these QSO's but rather just text sent in the blocks that happens with the TOR modes. A bit closer to Asia I was able to work a few Japanese stations as well as a gentleman in Thailand. Unfortunately, I was never able to work any Australians on Pactor, and only a couple on SSB. I was also able to get on PSK31 a few days and even worked some 10 meter SSB, although I am not too partial to voice these days. What is really fun is seeing how the change in location (about 350 miles a day) did to propagation. An area you worked yesterday just fine, will no longer be coming in, and a new area you haven't heard yet, will come in no problem. I did try to take a listen and even called CQ on 6 meters, but the band wasn't open, so no joy in the VHF part of the spectrum. It was a good trip as far as radio went, and we will see how it goes next time out there. 73 Jeremy

Field Day in EPA

The MURGAS ARC in Wilkes Barre, PA went out to Francis Slocum State Park near Dallas, PA this weekend for the ARRL's annual Field Day. Field Day is when various clubs and indviduals go out into the "wild" to operate portable stations, usually on emergency power, to ensure that the US and Canada have reliable stations and skilled operators in case a communication failure occurs. The club ran a class 3A station this year. In addition to the 3 main stations, a GOTA (Get on the Air) bonus station and VHF station were also on the air. There were three trailers for the main stations while the GOTA operated out of a tent. Two short towers were erected as well as a ground mounted vertical. The club had the ability to operate between 160 and 2 meters. Station was set up on the vertical and a tree mounted antenna. This enabled the station to operate 160, 80, and 40 meters on the vertical, and 20 and 15 meters on the tree antenna. This station operated primarily on the lower bands using CW. The rig was a TenTec Orion VII running 100 watts. Station 2 was for SSB on the higher HF bands and was working a 3-element trapped Yagi. This was the station I worked for about 30 minutes on 15 meters. It had a rotor and the rig was an Elkcraft K2 running about 80 watts out. The third station was running an older kenwood rig on a low 80 meter dipole that acted more like an NVIS antenna than anything else. In the same trailer the VHF rig was running 6 meters to a maxon antenna as well as a longer 2 meter yagi. The GOTA station was running a Icom 7200 to a buddypole. I had never seen a buddy pole in person before, but it seemed a reasonable antenna if a bit of a pain to tune with having to raise and lower the whole thing to tweak the elements. I was only at field day for a few hours on Saturday afternoon. 80 meters and the VHF bands were essentially closed, with modest acvity on 15 and 40 meters. When I worked the rig, the bean was heading west and I was able to work a good number of California stations as well as a few western stations. They seem to come in small bursts followed by long periods of silence. Not a full blown contest style FD by any means, but a good chance to check out what we can do in the field with compromise equipment and low power.

new batteries

About ten years ago my father bought me a portable power station for Christmas. It is a plastic box with a pair of cigarette lighter plugs as well as a set of lugs in the back connected to a 7 AH battery in the case. The power station offered a portable 12 V power supply that is effective to charge batteries for scanners and cell phones as well as antenna relays and TNC's. You could operate a low power radio for a bit of time, but with a 7 AH battery, it won't last too long, so I didn't use it for such purposes.

About a year later, a presentation at a local ham club showed a similar box, with the same internal battery, but this one was much more versitile. In addition to two cigarette lighter sockets, and lugs, a 100,000 candle power spotlight as well as a regular flashlight with blinker option and 9, 6 and 3 volt coax sockets are all included.

About a year ago the batteries started to die on me and I finally got around to buying new ones this month. I opened up the cases and replaced the cells. The power box with the light was easy as it was just plugged in with the lugs. The original box had soldered lugs which made life a bit more difficult.

The hardest part was actually getting the cases back together by getting the wires running through the tight spaces so that the cases could close again.

So after less than $20 of new parts, I have two fully-functional portable power supplies and auxillary lighting.

73

First steps to DXCC

While I have been a ham since 1997, and been active on HF since 2000, I have moved so many times that I've never officially earned my DXCC. I have worked well over 100 countries from various locations, and under various callsigns, but never enough from one place to earn my certificate.

So here I am in PA (W3 land) and I am starting all over again. I have ordered my new QSL cards and even put up a rather pathetic ground mounted screwdriver antenna with four radials to get me started.

I have been on a pactor kick lately, so went to the pactor watering hole on 20 meters, 14.111 CF. So I hooked up my SCS PTC-IIe to my Icom 746 and put out a rather pathetic 30 watts. As is normal with ARQ modes, you set the radio up to call CQ every minute or so and hope someone wants to chat and answers you. For my part, I swivel around in my chair and use another computer while calling and listen for connection noise in the form of the TX/RX relay in the rig to start clicking every few seconds.

I was watching a youtube video and this very thing happened. Imagine my surprise when I look at the screen and see not a US station, but one from across the Atlantic from England on my screen. G4APL was making a link and soon enough we were chatting amicably enough using pactor II. He was using a beam antenna and I was receiving good S8 signals. My signal, even with his beam was reaching him at S1 at best, so it was slow going at times. Still, even with repeats, with the 200 bps speed of Pactor 2 at it's most robust level, it was quite fast enough to have a keyboard to keyboard conversation.

A few days later I was at it again and this time I was able to work Peter OZ1PMX from Denmark, at first on pactor 2, and then on pactor 3. My signal was even worse into Denmark, so even the robust Pactor 2 was dropping the signal quite a bit. When we upshifted to pactor 3, we were able to maintain the link quite well.

So for DXCC, my first country was not the US, but England, and followed by Denmark. Last night I worked Brazil and the Maldera Islands for my third and fourth entities. One of these days I'll have to work the US. I am just hoping to get out there with a slightly better signal and finally get 100 countries from one place.

Until next time, 73.

VE session

Here in the US amateur radio license exams are given by trained volunteer examiners (VE's). I am new to Northeast Penn, so was not connected in with the local examiners, but I am a member of the MURGAS club and when a cry came out for an Extra Class examiner in nearby Scranton, I took up the challenge. I have not participated in an exam session since 2006, so I thought I would be rusty. Fortunately it all came back to me fairly quickly.

We have four candidates show up for the exam. Three were trying to obtain their license (Tech class) and one was attempting to upgrade to Extra (hence the need for me).

I am happy to report the W3ATS aquired his Extra license with no problem, while the other four candidates were able to pass their tech exams and earned their licenses. I just wish that there were more young people looking to get licensed. None of the new licensees were younger than 30, and two were in their 60's and 70's. We need to figure out a way to get the youth more involved.

73
Jeremy N1ZZZ