[R-390] Mason Labs R-390A?

[Barry]

Whatever they used, it certainly wasn't HiFi.  It's almost surprising how narrow and plastic sounding the audio was from the Apollo days and it hasn't really gotten that much better - at least not what's broadcast on TV from the Space Station, etc.

Thanks,
Barry - N4BUQ

----- Original Message -----
> From: "Tisha Hayes" <tisha.hayes at gmail.com>
> To: "R-390 Mailing List" <r-390 at mailman.qth.net>
> Sent: Sunday, January 30, 2022 9:29:38 PM
> Subject: [R-390]  Mason Labs R-390A?

> Some people romanticize the idea that the R-390A was used to listen to
> Apollo moon landings but the reality was different;
> 
> The Apollo missions primarily operated in the S-Band (around 2.1 GHz) with
> some backup capability at 296.9 MHz. If you dig in the references you will
> see that the Gemini capsules did have HF capability at 15.016 MHz but it is
> not documented if it was ever used. By Apollo the references to the 15.016
> MHz system was dropped but maybe it was something available as a
> post-splashdown SAR/recovery unit in addition to the 296.9 (and maybe
> 243.0) aviation-type radios.
> 
> In the S-Band the system operated off of a PM (like FM) carrier with
> sub-carriers for voice and telemetry. Some of the sub-carriers could be
> turned off and the main carrier was also used for position/ velocity
> tracking with a pretty high degree of accuracy.
> 
> At one time I thought that the capability of putting an external oscillator
> on an R-390A might have something to do with compensating for doppler shift
> (from spacecraft motion) but it makes more sense that it would be used for
> high-stability operations with HF RTTY/Data on fixed or maybe even
> shipboard operations. During Apollo, NASA had lots of tracking stations on
> land and at sea.
> 
> *Ms. Tisha Hayes*
> 
> *AA4HA*
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