Re: [Discuss-gnuradio] CT1FFU converter with RTL-SDR and gqrx

[Ron Economos]

There's a high pass filter on the output that is designed to pass 
frequencies above 150 MHz. If the LO is only 40 MHz, the high pass 
filter will greatly attenuate the entire HF band.

Ron

On 04/18/2016 11:12 AM, Daniel Pocock wrote:
> After looking at the different upconverters, I decided to try the CT1FFU
> device[1] first.
>
> The marketing says it is available with either 106.25 MHz or 65.520 MHz
> LO.  The manual[2] only mentions a 106.25 MHz LO
>
> I was initially using the offset -106.25 in the gqrx configuration.  I
> wasn't receiving anything, so I started to investigate:
>
> - the RTL-SDR doesn't see anything on 106.25
>
> - the upconverter I received has a 40 MHz oscillator on the board in the
> same place as the 106.25 oscillator in the photo
>
> - the RTL-SDR detects the 40 MHz signal and if I pull the power from the
> upconverter, the 40 MHz signal disappears
>
> Using -40.0 MHz in the gqrx config, I still don't find anything on HF though
>
> Are there any known issues with gqrx or GNU Radio in general with this
> type of setup?
>
> Is it necessary to add band pass filters or LNAs with the upconverters
> or should they work standalone?
>
> Can anybody make any other comments on testing it further?
>
>
> 1.
> http://www.rtl-sdr.com/version-5-0-of-the-ct1ffu-upconverter-now-available/
> 2. http://www.ct1ffu.com/site/images/stories/FCD5a.pdf
>
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