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Wednesday, June 16, 2010

The Last Roman Rig: New WSPR DSB Transceiver

They are coming to pack up my soldering iron next week, so I'm afraid this will be my last Roman creation. You can see the W3PM Colpitts oscillator in the center. The KA7EXM AF amp is in the lower left. The Softrock-based Manhattanized PA is in the upper right. To the right of the oscillator is a classic W1FB two diode balanced modulator. You see three big green relays. The top one switches the antenna and 12 volts during T/R switching. The middle one switches the audio amp input, the bottom one switches the audio amp output. (I use the same AF amp for receive and transmit, just switching around the input and output.)

It works fine and has sent and received WSPR sigs. I think it will also do PSK-31 with the FLDIGI program. I could use a one more stage of RF amplification between the balanced modulator and the PA driver amp. Also, the AF impedance match between the KA7EXM amp and the balanced modulator nees work: Roger's circuit was deisgned to drive high impedance phones. That balanced modulator circuit has about 50 ohms at each port. Ideas?

I was thinking of calling it the Achilles. But I think I will go with "L'Aquilone" (The Kite").

2 comments:

  1. Sorry to hear your Roman adventure is almost over. Looking forward to catching your QRSS locally in NoVa. Congratulations on the L'Aquilone, it is a very ugly rig!

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  2. Well drat. I was hoping to run into you in Rome in November when I come to RIPE 61. If you're back in NoVA for a while I hope you join the AMRAD crew at Tippy's in Merrifield on Saturdays (see http://www.amrad.org/meetings/ )

    73 de AI4UC

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