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 http://ea4eoz.ure.es/lfpream.html
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 box this is also a J-Fet hi input impedance op-amp like the TL081.
The DCF39 data signal at 138.8kHz became 9+60 at the IC706 Using my receive only port modification done years ago for a 50MHz preamp. http://www.ke3ht.org/ic706-rx-port.html
Now the preamp is protected against unwanted RF from the IC706 whenever the TX /PTT is switched in by mistake.
Before going to sleep I tuned USB 0.510000 kHz WSPR for the rest of the night and switched of band hopping to have 100% receive time for :
WE2XGR/6 WE2XGR/2 and WE2XGR/3
Id did not know what signal to expect. Last week was poor only 4 decodes /night for WD2SXH/17 at 501090 (Dial USB 499.600)
But real SUPER SIGNALS !!
WE2XGR/6 200+ decodes continuous strong trace over the screen with no interruption to -1dB
Best signal ever from USA audio strong would be a 559 or more i guess that would be simple CW or even SSB level to copy.
Last decode was 07:50 in broad daylight -27dB
also WE2XGR/2 copied 48 times -9dB
and WE2XGR/3 72 times -16dB