From: "jrusgrove@comcast.net" <jrusgrove@comcast.net>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
References: <10f465fa-37f0-4ac6-b53d-793f955ea011@email.android.com>
 <5C19FFCB.1060305@posteo.de>
 <0E0AEF52-CE89-4E56-A2E1-77C2F9815B4B@md.metrocast.net>
Date: Wed, 19 Dec 2018 07:13:43 -0500
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Subject: Re: LF: Ebnaut receiver frequency stability qustion
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> Additional thoughts and suggestions are welcome.

If using an untuned loop or e probe antenna (any untuned antenna for that matter) you'll want to include a front end filter to remove the image. Even if there are no signals at the image frequency you still don't want the noise contribution.

Jay W1VD   


----- Original Message -----
From: Rob Renoud <k3rwr@md.metrocast.net>
Reply-To: <rsgb_lf_group@blacksheep.org>
To: <rsgb_lf_group@blacksheep.org>
Sent: 12/19/2018 6:58:56 AM
Subject: Re: LF: Ebnaut receiver frequency stability qustion
________________________________________________________________________________

Hi Stefan, Luis, LF EbNaut,

There are several who believe the converter circuit approach is a viable path to  EbNaut RX capability.  I think three things are needed at this point:

1) Circuits
2) Identification of suitable Local Oscillator hardware (possibly for both RX and TX)
3) Clear and concise software configuration and operation instructions for Spectrum Lab, EbNaut-tx, EbNaut-rx, etc.

Toward that end, I will set up a converter circuit and begin tests using K3SIW’s LowFER EbNaut beacon on 185.185... kHz with the goal of producing EbNaut configuration and operation instructions for the converter approach.

Additional thoughts and suggestions are welcome.

73,
Rob - K3RWR 

> On Dec 19, 2018, at 03:22, DK7FC <selberdenken@posteo.de> wrote:
> 
> Hi Luis, LF,
> 
> I agree, this is indeed the most reasonable design. Using the same here ;-) but a 125 kHz LO, locked to GPS.
> Maybe we should provide easy converter crcuits. A compromise between high end and easy to build up, for the 'EbNaut-newcomers'?
> 
> 73, Stefan
> 
> Am 19.12.2018 07:39, schrieb VIGILANT Luis Fernández:
>> 
>> Hi EbNaut
>> 
>> I think that using expensive receivers is NOT the way to go. I'm using a simple mixer as downconverter. The LO is 120KHz generated from a uBlox GPS. So the 137KHz outputs as 17KHz and can be feeded to PC soundcard. The second channel of GPS provides 1pps to discipline the soundcard using Spectrum lab
>> 
>> Not using filters at all and no amplifier stages. So there is room for improvement, but it works
>> 
>> 73 de Luis
>> EA5DOM