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Tuesday, April 15, 2014

AA1TJ Crosses the Pond with 10 milliwatts



From a Facebook Post by Mike, AA1TJ:

Made 7 contacts with this tiny transceiver on 20m CW today with an RF output power of 10milliWatts. Five were stations in Georgia (GA QSO Party). The 6th was a regular QSO with a guy in Mississippi.
I answered a DX station calling CQ at 2230Z. Hearing nothing in response, I sent my call sign a half-dozen times anyway. More silence. As I was reaching for the knob to QSY he suddenly returned my call! ...Carlos, CT1BQH northeast of Lisbon, Portugal (that's him in the second photo). I was only 329 on his end but we kept it going for three minutes!
FYI: the transmitter (top circuit board) begins with a 3.58MHz ceramic resonator VXO (a 2N706 from the early 60's). That drives a push-push frequency doubler built around another 1960's-vintage, 2N2644 (obsolete stock from atop Mt. Mansfield, kindly given to me by Rich at Vermont Public Television). On receive, the 7MHz energy is routed via a DPDT relay (the orange rectangle) to the sub-harmonic (Polyakov) mixer located on the lower board. One stage of AF amplification is provided by a 2N333 that came off the GE assembly line in November of 1958. The DPDT relay is keyed directly. On transmit the 7MHz energy feeds a second push-push frequency doubler to produce 10mW at 14MHz (all spurs -35dBc, or less, with only the output resonator). The relay also switches the antenna between the transmitter and receiver.
Gosh, that was fun!

CT1BQH

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2 comments:

  1. Wow! Cool radio and amazing QSO. I tried my ~200mW Pititico during that same GQP contest but on 40m, and no dice! What kind of antennas are you running there Mr. Rainey?

    I hope you re-start your blog again, would love to follow your adventures.

    ReplyDelete
  2. Thanks for the post, Bill. Thank you for your comment, Bert. My antenna's nothing to write home about: an end-fed, 135' long wire at ~35'.
    I've been neglecting all sorts of things here (my blog included) since I got the idea of writing a book in my head.

    Anyway, I had another great contact with my little transceiver this evening. F8DGY, calling CQ from near Paris came right back to me with a 539. We ended up chatting for six minutes: "VY FB CPY MIKE WITH 10mW IN VT MY BEST EVER". I think he was as excited as I was. I love it when that happens! 73/72, Mike

    ReplyDelete

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