I’m looking for a way to tap into the unmodulated signal in my ICOM 706
MKIIG (I don’t have a SDR BUT I do have a sound card, and lots of ham
equipment 
).
Referring to the product service manual[1], I have found the “product
detector” signal before it reaches the AF stages.
Also it appears (hoping I’m wrong) that the second IF runs at about
9Mhz. So
does that mean that I need to down-convert the signal from 9Mhz, to
something the soundcard can handle?
Or is there a better place to tap the IQ signal coming from the VDO…?
Anybody else had any success in tapping the IQ in a receiver and feeding
that into GNURadio?
73
K1GTO
BH
References
[1] RigPix Database - Icom - IC-706MKIIG
On 12/31/2010 02:24 PM, Brad H. wrote:
9Mhz, to something the soundcard can handle?
Pulling off a signal from the 2nd IF would likely be doable. But you’ll
need to convert it to quadrature baseband somehow.
Most “traditional” receivers do not have a quadrature architecture.
You might look into getting something like a “SoftRock 40” and modifying
it to produce a quadrature conversion to baseband from
9MHz, instead of the nominal 7.1MHz that the “Softrock 40” is
designed for. I think the “SoftRock” series uses a Tayloe
detector, whose crystal clock runs at 4X the nominal conversion
frequency.
If you can identify the point in the receiver where the 9MHz IF is at
roughly 50Ohms impedance, it should be quite straightforward.
–
Marcus L.
Principal Investigator
Shirleys Bay Radio Astronomy Consortium