[amsat-bb] Shack re-wiring: RTL-SDR options?

[Jim Jerzycke]

I know there are plans for simple upconverters out there, but I've never 
built one.


I've owned most of the SDR receivers out there, from $5 dongles to both 
FunCube dongles, the HackRF One, SDRplay, and now the AirSpy. Depending 
on what you want to use them for, and *where* you're located, they can 
be really cool, or a disappointment.


Here in the RF Alley of SoCal, the cheap dongles can really fold up on 
strong signals many, many MHz away from the signal-of-interest.


Jim


On 03/03/2017 04:40 AM, Greg D wrote:
> Doh!
>
> Well, that answers that question.  Thanks, Jim.  You are correct!  24.00
> is the minimum Gqrx will let it go.
>
> Greg  KO6TH
>
>
> Jim Jerzycke wrote:
>> I don't think an RTL dongle will tune down that low.
>>
>>
>> Jim  KQ6EA
>>
>>
>> On 03/02/2017 10:46 PM, Greg D wrote:
>>> Hi folks,
>>>
>>> Has anyone used an RTL-SDR dongle on the 10.7 MHz IF output from another
>>> receiver?  Is that better than going direct?
>>>
>>> My cable TV provider is forcing us to go all-digital.  With the new
>>> "cable box" comes the opportunity to re-wire the shack and simplify the
>>> many layers of cables, splitters, and lash-ups that have accumulated
>>> over the years.  The proverbial camel is crying out for help.
>>>
>>> What this has to do with Ham Radio is that part of the lash-up mess is
>>> an old pre-CATV deep fringe TV antenna that I have in the attic, aimed
>>> to the southern horizon.  We are well outside the range of any of the
>>> digital OTA stations, and never one to leave a perfectly good piece of
>>> RF equipment go to waste, I currently have it fed to an old Icom R-7000
>>> scanning receiver (previously used as the AO-40 downlink IF) and to an
>>> RTL-SDR dongle by way of a TV 2:1 splitter.  I've tried hooking the
>>> dongle directly to my 2m ham antenna for satellite use, but for some
>>> reason that was less than satisfactory.  Never really did hear much of
>>> anything, and never could figure out why.  At least with the TV antenna,
>>> I can copy some stuff with the dongle, though the Icom is generally
>>> better.  But the Icom doesn't do the various digital modes that are
>>> better suited for SDR.
>>>
>>> Looking at the back of the Icom, I see that it has a 10.7 MHz IF output,
>>> so the thought is that the SDR dongle might perform better hooked there
>>> (with a DC bias block) instead of to the antenna itself through the
>>> splitter.  Both receivers have similar frequency coverage, but perhaps
>>> the Icom, while somewhat deaf by modern standards, might still make for
>>> a better front-end to the dongle?
>>>
>>> I think the down-side is that the Icom's IF bandpass is narrower than
>>> the Dongle's, so I'd lose some flexibility there.  I would also lose the
>>> ability to software-control the frequency of the receive chain, outside
>>> of the IF bandpass.
>>>
>>> What do you think?  Would this be a net win or loss for the RTL-SDR?
>>>
>>> Thanks,
>>>
>>> Greg  KO6TH
>>>
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>> _______________________________________________
>> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
>> to all interested persons worldwide without requiring membership.
>> Opinions expressed
>> are solely those of the author, and do not reflect the official views
>> of AMSAT-NA.
>> Not an AMSAT-NA member? Join now to support the amateur satellite
>> program!
>> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
>