|Subject:||LF: 500kHz simple 5W TX/RX transverter|
|From:||Roger Lapthorn <[email protected]>|
|Date:||Tue, 8 Dec 2009 00:20:13 +0000|
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My WSPR tx up-converter has now been modified to a full TX/RX tranverter suitable for WSPR, QRSS and CW in a very simple way, making use of the FT817 split facility which allows you to RX on 500kHz and TX on 28MHz. By adding a series LC between the TX PA and the FT817 input/output RF connection (with back-to-back diodes at the L and C junction, this allows "pass through" from the 500kHz ATU to the FT817 on RX (tuned to 500kHz). On TX, the diodes conduct and the C part is in parallel with the first cap in the TX low pass filter. This scheme is now working really well with good RX sensitivity and no change in TX power out.
Schematic of the transverter is on my blog at http://g3xbm-qrp.blogspot.com/ . My attempt to add it as an attachment to an email here earlier failed.
This more or less concludes my 500kHz experimenting, apart from getting a few more CW QSOs in the log. It's been great fun all the way with lots of support from folks here. I was going to try 136kHz, but think I will now give this a miss for now.
G3XBM GQRP 1678 ISWL G11088
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