Message-ID: <7AE7CA77B9414B2C854DFF04F743A735@AGB>
From: "Graham" <g8fzk@g8fzk.fsnet.co.uk>
To: <rsgb_lf_group@blacksheep.org>
References: <ocp54c+m7ls3@YahooGroups.com>, <5E4B3FA1CBBB46C0A8F875AD0B19DB9A@AGB>, <Pine.LNX.4.64.1704141234350.26198@plato.ucs.mun.ca> <58F1F150.23378.92337D@roelof.ndb.demon.nl>
In-Reply-To: <58F1F150.23378.92337D@roelof.ndb.demon.nl>
Date: Sat, 15 Apr 2017 14:32:22 +0100
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Subject: Re: LF: Re: [rsgb_lf_group] VO1NA   477  OP8 :Start 2300 finish 0900 50 watts to  monopole.
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Status: O

Good set of results from last night Roelof !

8 bit AD ,  seam's to be various lines  on this ,  but the  8 bits is the 
resolution against a  reference ,  if the  ref  is , say 1 volt and the 
wanted  is 2  volts , then  you have  , 256 steps  ~  4 mV  per  step   1 
volt  to  20 , then  the  steps  are ~  40 mV   etc  , I'm not sure , hard 
numbers  are directly related to in use performance , as  the  control 
software has a  role to play ... along with circuit design

I live close to a  10k  MW  tx  , and  the  RTL dongle  on 80/60  meters , 
gives a  cleaner  Rx than  the  ft897d  from the  same  Ae , the skanti 
r5000 , needs a  band pass  filter  to  stop  cross  modulation  and the 
racal  6790gm ,  no pre amp ,  has no  issues , but  deploys  5 to 7 watts 
Rf drive to the  first mixer ..
to give about 120 dB dynamic  range .

73-Graham
G0NBD

--------------------------------------------------
From: "Roelof Bakker" <roelof@ndb.demon.nl>
Sent: Saturday, April 15, 2017 11:09 AM
To: <jcraig@mun.ca>; <rsgb_lf_group@blacksheep.org>
Subject: Re: LF: Re: [rsgb_lf_group] VO1NA   477  OP8 :Start 2300 finish 
0900 50 watts to  monopole.

> Hello Joe,
>
> Attached your OP8 signal as received here last night on a Afedri SDR
> and mini-whip antenna. At it strongest I had aural copy.
>
> You probably have seen my reports on your Opera window.
> These were received using a 20 dollar RTL-SDR V3 in direct sampling
> mode under SDR#. Dispite the only 8 bit ADC, it looks that it can be
> pressed in service when you use proper front end filtering.
>
> If I am correct, an 8 bit ADC can provide a dynamic range of about
> 50 dB. This is not much when compared with e.g. a PERSEUS which
> provides a dynamic range short of 100 dB. The question is how much
> dynamic range you really need in practice.
>
> The famous Drake R4C has, as measured by Sherwood, a dynamic range
> of just 58 dB. Due to an excellent pre-selector it is a nice
> receiver.
>
> Anyway, I am very pleased with the result.
>
> 73,
> Roelof, pa0rdt
>


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