[amsat-bb] Shack re-wiring: RTL-SDR options?
ko6th.greg at gmail.com
Fri Mar 3 04:40:50 UTC 2017
Well, that answers that question. Thanks, Jim. You are correct! 24.00
is the minimum Gqrx will let it go.
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?
>> 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
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