rcvr designs prc-2000 USES DIRECT CONVERSION!

[WA2JJH]

Some have doubted the K2's RCVR. ""It is only single conversion"" My  radiois
quad conversion!
 
Check this out, My friend KA4KOE purchased a military field rig. The  
PRC-2000 is current issue in some places that do not use encrytion.
 
  He would joke about my K2 manpack. His used PRC-2000 cost over  $2000.
The receiver used.   DIRECT CONVERSION. THEY DID FIND A WAY TO  GET RID OFALL
THE AUDIO  ARTIFACTS AND IMAGES THAT WERE THE REASON WHY  SUPERHET BET DIRECT
CONVERSION AS THE GOLD STANDARDOF RCVRS.
 
   INSTEAD OF XTAL FILTERS, STAGES OF ACTIVE OP AMPS AND AUDIO  COILS AND
CAPS. OK AUDIO DSP IS USED GREATLY!
 
THE RECEIVER IS VERY HOT. HE WORKS DX WELL. THE PRC-2000 IS ALSO  15-20W
SSB.
 
   I THINK  DX OFF IS NEEDED TO SEE WHICH RADIO IS  BETTER!
pHIL IS ALL FOR IT.
 
PERHAPS WHEN THE WX IS BETTER, IT WILL BE BATTLE OF THE MANPACK  RIGS!
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[Geoffrey Mackenzie-Kennedy-2]

Another example is the Collins 95S-1A produced some years ago. This receiver
is 'Software Driven' and covers the range from 5 kilohertz to 2 GHz in steps
down to 1Hz. Its architecture is hybrid. Antenna signals between 5 kHz and
30 MHz are upconverted to 51.2 MHz and directly converted from there to
baseband - e.g. audio.  Antenna signals between 20 MHz and 2 GHz are
Directly Converted to baseband, and yes there is an overlap between 20 MHz
and 30 MHz. Baseband signals are processed by DSP. Modes handled are CW,
L.SB, U.SB, I.SB, FM and AM.

IMHO Direct Conversion has great performance potential, and the techniques
in circuitry developed during the past decade could perhaps make Direct
Conversion the architecture of choice sometime in the future. There is no
doubt in my mind that SSB signals sound "better" from a DC receiver,
likewise CW.

73,
Geoff
GM4ESD


----- Original Message -----
From: <[hidden email]>
To: <[hidden email]>
Sent: Tuesday, March 15, 2005 3:41 AM
Subject: [Elecraft] rcvr designs prc-2000 USES DIRECT CONVERSION!

>   He would joke about my K2 manpack. His used PRC-2000 cost over  $2000.
> The receiver used.   DIRECT CONVERSION. THEY DID FIND A WAY TO  GET RID
OFALL
> THE AUDIO  ARTIFACTS AND IMAGES THAT WERE THE REASON WHY  SUPERHET BET
DIRECT
> CONVERSION AS THE GOLD STANDARDOF RCVRS.

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[stephen Farthing]

Gentlefolk,

    I am part of a group of fellow Amateurs who have been working on
homebrew phasing Direct Conversion Tranceivers for a while now.
Details of our first attempt can be found at: -

www.stevef.demon.co.uk/qrp2k/qrp2000home.htm

and the later iteration is at
http://www.qrp2001.freeserve.co.uk/background.htm .


 Design and prototyping for the QRP2004 is well underway and will be
published when we can get round to it. These are homebrew designs, the sad
thing is that we were trying to get someone with more time that we have to
kit them however there was little interest at the time we presented the
QRP2000 at Dayton. I think we have all built, or in my case are building K2s
as well. There is something about the clarity of the audio from a DC RX
which superhets never manage to achieve. The first ham project I ever made
was a Sudden DCRX uring the venerable NE602...I had a lot of fun with
it....and was hooked....

Bye for now,

Steve




----- Original Message -----
From: "Geoffrey Mackenzie-Kennedy" <[hidden email]>
To: <[hidden email]>
Cc: "Elecraft Discussion List" <[hidden email]>
Sent: Tuesday, March 15, 2005 9:43 AM
Subject: Re: [Elecraft] rcvr designs prc-2000 USES DIRECT CONVERSION!

> Another example is the Collins 95S-1A produced some years ago. This
> receiver
> is 'Software Driven' and covers the range from 5 kilohertz to 2 GHz in
> steps
> down to 1Hz. Its architecture is hybrid. Antenna signals between 5 kHz and
> 30 MHz are upconverted to 51.2 MHz and directly converted from there to
> baseband - e.g. audio.  Antenna signals between 20 MHz and 2 GHz are
> Directly Converted to baseband, and yes there is an overlap between 20 MHz
> and 30 MHz. Baseband signals are processed by DSP. Modes handled are CW,
> L.SB, U.SB, I.SB, FM and AM.
>
> IMHO Direct Conversion has great performance potential, and the techniques
> in circuitry developed during the past decade could perhaps make Direct
> Conversion the architecture of choice sometime in the future. There is no
> doubt in my mind that SSB signals sound "better" from a DC receiver,
> likewise CW.
>
> 73,
> Geoff
> GM4ESD
>
>
> ----- Original Message -----
> From: <[hidden email]>
> To: <[hidden email]>
> Sent: Tuesday, March 15, 2005 3:41 AM
> Subject: [Elecraft] rcvr designs prc-2000 USES DIRECT CONVERSION!
>
>>   He would joke about my K2 manpack. His used PRC-2000 cost over  $2000.
>> The receiver used.   DIRECT CONVERSION. THEY DID FIND A WAY TO  GET RID
> OFALL
>> THE AUDIO  ARTIFACTS AND IMAGES THAT WERE THE REASON WHY  SUPERHET BET
> DIRECT
>> CONVERSION AS THE GOLD STANDARDOF RCVRS.
>
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[Brendan Minish-2]

On Mon, 2005-03-14 at 22:41 -0500, [hidden email] wrote:

The PRC 2000 is a hot receiver for ssb work, it sounds a little odd (but
very punchy (due to the hole carved in the centre of the audio passband
by the I/Q modulator / demodulator

>    INSTEAD OF XTAL FILTERS, STAGES OF ACTIVE OP AMPS AND AUDIO  COILS AND
> CAPS. OK AUDIO DSP IS USED GREATLY!

the PRC 2000 uses no DSP whatsoever

> THE RECEIVER IS VERY HOT. HE WORKS DX WELL. THE PRC-2000 IS ALSO  15-20W
> SSB.

It's also a pig to free tune but the TX audio has a lot of punch

>    I THINK  DX OFF IS NEEDED TO SEE WHICH RADIO IS  BETTER!
> pHIL IS ALL FOR IT.

The K2 is better, no contest but the PRC2000 is a nice radio, I can't do
a side by side right now, my PRC-2000 is stuck in the northern Russian
arctic as part of the 'get out' kit on northabout, www.northabout.com  

73
Brendan Ei6IZ

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