Good Afternoon Group,
The mention of 1/3 subharmonic sampling and SDR tuning made me pause. I think I use to know this but it seems at almost 81 years old lots of things don't stay in my memory very long.
Here is the result of an experiment:
Rocky 3.8 in use showing a spectrum display with an RX II receiver board.
RX II setup so that the BP filter for 8-16 MHz is used for any center frequency commanded between 4-16 MHz.
Center frequency of 15.003 MHz commanded and WWV is a strong signal at 15 MHz on the Rocky spectrum display.
Center frequency of 5.003 MHz commanded and now a fairly strong WWV signal shows at 5.0012 on the Rocky spectrum display as well as weaker WWV signals at 4.997 MHz, 5.0 MHz and 5.009 MHz.
The WWV audio time announcements and other audio tones seem to be about the same when listening with the center frequency set to either 15.003 MHz or 5.003 MHz.
Does this make sense?
Regards,
Tony, kb9yig
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On Dec 4, 2021, at 3:43 AM, Alan G4ZFQ <alan4alan@...> wrote:
The FT-301D's IF is about 9 MHz. The SRL II Oscillator is 11 MHz, but it is 1/3 undersampling. Not sure what that does to the tuning.
No, the FT-301D does not have electronic tuning. It is all Analog. No USB or Ethernet cponnectivity.
George
Sorry, did not think that it might be that old:-)
Then the SDR tuning will be fixed and not show the rig's frequency unless you set it manually, only practical if you rarely move frequency.
There will be an offset between your IF centre and the SDR centre. I think one of Tony's crystals needed 96KHz sampling to include the IF centre.
You should try tuning the rig to a signal and find it on the SDR.
Overloading could be a reason for bad results.
73 Alan G4ZFQ
