Showing posts from January 6, 2011

Receiving 137kHz with the IC706

For WSPR at 137kHz to filter out the DCF39 signal at 0.1388kHz I make use of the CW 500Hz filter in my IC706. Receiving(only) with the IC706 in position CW-narrow using the 500Hz CW filter is possible settings: IC706 Dial:   0.137500  mode CW-R  (for USB this must be 0.13600 to bring the audio in the center of USB filter) WSPR: Advanced : Rx BFO (Hz) 570 (in my case) to adjust the audio at the correct frequency in the band.  (1500 by default for USB mode)  WSPR Dial: 0.137000  Brings the displayed frequency ruler  400-600  meaning 0.137400---0.137600   Tx  0.137500  (no TX Txfr =0)   Decoding is good  decoding traces as low as -31db
But   i have a problem that i could not fix yet: The reported frequency is consequent 72Hz to high for all signs.The trace position and frequency at the screen are correct.
F.i. PA0A = 0.137450 correct on the screen and also this is his correct TX frequency.  But it is reported as 0.137522kHz I change WSPR dial  then the ruler  will display  him on the wrong freq.…

My first 137kHz HAM signal received. & the night at .510kHz for WE2XGR test

My first ever 137kHz  HAM signal  G8IMR  -23dB    on the IC706 USB + preamp.  I listened  only 15 minutes on 137 it became too late already again  glad that it worked  i saw 3 traces of G8IMR    it decoded 2 times. The tracking screen was relative clean although the DCF39 was still s9 in the USB filter  of the IC706. There where some weak thin lines drifting  and clearly distinctable the frequency stable and exact timed  trace of G8IMR.

Last night I finished my preamp
thanks Miguel  A. Vallejo, EA4EOZ

Although  it is a simple thing it took me 2 evenings  to build and get it working.
Needs a small  modification for use with a 50 Ohm signal source  like my K9AY antenna.  It did not work  with the high impedance C 33p  input antenna connection not even the DCF39 signal could come trough!

I connect the K9AY coax  at the low impedance (13uH)  2 pin coil of the first band MF transformer that is not connected in the original.
I use a metal can CA3140 from the junk…