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Tuesday, December 14, 2010

Immediate Gratification: WSPR shows results very fast

So you build or modify a rig and you put up a new antenna and you then spend some time wondering if you're really "getting out," right? Well, wonder no more my friends! WSPR provides almost instant feedback on your work! Here is what the display looked like for my station a short time after I connected my modified transceiver to my new 30 meter dipole. Pond crossings were rare events before.

In my last post I asked if there were others running homebrew gear on WSPR. I am not alone! Paul, M0XPD, has put together a rig far more sophisticated than mine. Paul writes:

You ask if there are any others running h/b in WSPR...
My 50mW multi-mode beacon runs WSPR, DFCW and S/MT Hell on a 10-minute, frequency-hopping cycle.
It is entirely stand-alone - severing the umbilical cord to the PC gave me a really good feeling!
I'm currently working on a set of filters (BP and LP) to allow me to run on other bands (currently I'm on 30m).
Description on my blog: http://m0xpd.blogspot.com

Sunday, December 12, 2010

A good radio morning at N2CQR

Today I had one of those really good ham radio mornings in the shack. My objective was to add one more amplifier stage between the balanced modulator and the power amplifier in my Roman WSPR DSB Direct Conversion transceiver. First I had to take the balanced modulator (trifilar transformer and two diodes in a singly balanced configuration) off the board and move back, closer to the AF input jack -- I needed to make space for the new amplifier stage. For that stage I consulted Doug DeMaw's books and Wes Hayward's EMRFD. I went with a feedback amp using a 2N3904 in Class A.

With coffee brewed and with my Drake 2-B tuned to the very congenial DX-60 net (75 meters AM on Sunday mornings), I turned to the junk box. It was like meeting old friends! I pulled out parts that Michael, AA1TJ had sent me. I pulled out others that had been sent by Jim, AL7RV. I got out my box of isolation pads that Jerry Felts, NR5A had sent in. Soon the parts were glued and soldered to a board that already had an AF amplifier designed by Roger Hayward, KA7EXM and a PA that is my "Manhattan-ized" version of Tony Park's SDR rig PA. At the center of the board is little Colpitts oscillator that I took from a WSPR rig designed by Gene, W3PM -- earlier in the week Gene had posted a comment on this blog saying he was pleased to see my call on his WSPR screen. I wonder if Gene realized that he was seeing the signal from an oscillator from his design! The laptop was provided by a listener who prefers to remain anonymous -- thanks OM! Nearby, a copy of "Lid, Kid, Space Cadet" by Jeff K1NSS provided encouragement.

The rig passed the smoke test so I moved it over to the operating position and put it on the air. I got immediate gratification: the WSPRnet map right away showed my signal (now around 200 milliwatts) being received all round North America. You can watch this LIVE by going to http://wsprnet.org/drupal/wsprnet/map Just plug N2CQR into the "Call" box and hit UPDATE.

I know that WSPR is not everyone's cup of tea, but I like it. It was fun to build this rig. While WSPR is almost exclusively a mode that uses store-bought equipment, I get a kick out of being one of very few ops using a homebrew transceiver in this mode. (Are there any others?)

Next steps: I need to figure out how to set up automatic switching (by the computer) from transmit to receive. And I want to make some PSK-31 contacts with this rig.

Thanks to all who contributed!

73 Bill

Friday, December 10, 2010

Need audio reports for Podcast 128

How did 128 sound? I did drop off the lows, but I used the same filter I used in 127.

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Thursday, December 9, 2010

Saturn and Rhea

After a long spell of looking almost exclusively at Jupiter and our Moon, I was very pleased to see that Saturn is now visible. It is up in the south-east just before dawn, to the upper right of VERY bright Venus. The Sky and Telescope screen shot is a good representation of what I saw. I was using a 6 inch reflector telescope. I could see Titan very easily, and I could also see Rhea by using the averted vision trick.
Above is a much better view of Rhea. This one was taken by the Cassini spacecraft last November. Rhea has been in the news recently because scientists have discovered oxygen in its atmosphere:
http://www.astronomy.com/en/News-Observing/News/2010/11/Cassini%20reveals%20oxygen%20atmosphere%20of%20Saturn%20moon%20Rhea.aspx

Wednesday, December 8, 2010

Lynn Marsh, Boy Telegrapher, 1909

Note the steely-eyed look of determination and confidence. That's the same look that we see in the eyes of the 1925 radio builders (scroll down), and in the eyes of other knack victims.

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