[amsat-bb] 70cm LNA

[Kevin Elliott]

Zach,

Are there any complete built filters to inline by chance from any retailer?

Sent from my iPhone

> On Aug 12, 2020, at 11:45 AM, Zach Metzinger via AMSAT-BB <amsat-bb at amsat.org> wrote:
> 
> On 08/11/20 21:47, Zach Metzinger via AMSAT-BB wrote:
>> Success! The SAW filter eliminated the offending cell-tower sources.
>> The noise floor barely moves when the preamp is switched in, while
>> the desired beacon signal increases significantly.
> The 3-D printed passive Lindenblad + homebrew LNA, driving 75' of look-alike-LMR400 is working well for receiving RS-44 now. The LMR400 is optional, as there is plenty of gain from the MAX2640 LNA, but was used to keep losses down when transmitting on this antenna.
> 
> I can reliably copy the RS-44 beacon about 8 degrees above the horizon, and SSB is quite readable at about 20 degrees.
> 
> A horizon-to-horizon pass recording is located here:
> 
> http://www.n0zgo.net/oscar/rs44_12082020_1802.mp3
> 
> (The good stuff starts at about 7 minutes into the recording. I chase the beacon at the end in CW mode, and it disappears at 5 degrees elevation.)
> 
> A FT-847 was used for reception, but a cheap SDR dongle would probably work just as well for a lost-cost entry into 70cm downlink capability (as required for the GOLF satellites).
> 
> Now to wire it up for automatic Doppler correction and we're in business.
> 
> 73,
> 
> --- Zach
> N0ZGO
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