Return-Path: Received: from rly-dd04.mx.aol.com (rly-dd04.mail.aol.com [172.19.141.151]) by air-dd07.mail.aol.com (v121.4) with ESMTP id MAILINDD074-b6f4787d62a2fa; Fri, 11 Jan 2008 15:48:57 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-dd04.mx.aol.com (v121.4) with ESMTP id MAILRELAYINDD041-b6f4787d62a2fa; Fri, 11 Jan 2008 15:48:44 -0500 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1JDQnu-0007mk-61 for rs_out_1@blacksheep.org; Fri, 11 Jan 2008 20:48:38 +0000 Received: from [83.244.159.144] (helo=relay3.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1JDQnt-0007mb-CW for rsgb_lf_group@blacksheep.org; Fri, 11 Jan 2008 20:48:37 +0000 Received: from qmta02.emeryville.ca.mail.comcast.net ([76.96.30.24]) by relay3.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1JDQnp-0002wa-TI for rsgb_lf_group@blacksheep.org; Fri, 11 Jan 2008 20:48:37 +0000 Received: from OMTA09.emeryville.ca.mail.comcast.net ([76.96.30.20]) by QMTA02.emeryville.ca.mail.comcast.net with comcast id bnCX1Y0050S2fkC0A0qt00; Fri, 11 Jan 2008 20:48:27 +0000 Received: from WarrenPC ([24.91.18.115]) by OMTA09.emeryville.ca.mail.comcast.net with comcast id bwnv1Y00L2Uxt088V00000; Fri, 11 Jan 2008 20:48:02 +0000 X-Authority-Analysis: v=1.0 c=1 a=HiwoZ1REcyFfZv7UXXsA:9 a=0U5L46suE_woNF6i6ViZs8h_gEYA:4 a=FEaNhf3AWQsA:10 a=Tbxd-tdfeeUIYHTuF6sA:9 a=7s9LjQawGQsnObiZk5wA:7 a=a3WhPRwkGTMf6A6jiCewd8OtUz8A:4 a=9xyTavCNlvEA:10 a=wk6s2zzMB60A:10 a=AfD3MYMu9mQA:10 Message-ID: From: "K2ORS" To: References: <88d2415e0801111045t1e31ee78vbaf955f4f2a9f3a8@mail.gmail.com> In-Reply-To: <88d2415e0801111045t1e31ee78vbaf955f4f2a9f3a8@mail.gmail.com> Date: Fri, 11 Jan 2008 15:48:16 -0500 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6000.16480 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6000.16545 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: LF: Re: LF Receiver Content-Type: multipart/alternative; boundary="----=_NextPart_000_07B6_01C85469.61D1AE50" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.9 required=5.0 tests=HTML_30_40,HTML_MESSAGE, MISSING_OUTLOOK_NAME autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-AOL-IP: 193.82.116.20 X-AOL-SCOLL-AUTHENTICATION: listenair ; SPF_helo : n X-AOL-SCOLL-AUTHENTICATION: listenair ; SPF_822_from : ? ------=_NextPart_000_07B6_01C85469.61D1AE50 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Laurie, From among my own receivers, I find that the Cubic 3280 is a very good DS= P receiver AND you can shut the AGC off. For non-DSP, the newer RACALs such as the 6830 work great and have switchabl= e AGC. An SLM such as the 3586 is a good choice if all you don't need an AM detecto= r. I agree with the comments on the R75 and AOR 7030- but both benefit from add= ing the cw filters. If price is no object QST claims that the Icom R-9500 is one of the best eve= r in terms of strong signal handling (though I can't confirm this from perso= nal experience yet). 73 Warren K2ORS ----- Original Message -----=20 From: lawrence mayhead=20 To: rsgb=20 Sent: Friday, January 11, 2008 1:45 PM Subject: LF: LF Receiver I have for a long time used a Racal 1792 reciever for QRSS modes on LF. This receiver failed recently,and I have been looking for a replacement re= ceiver. This search reveals a problem most modern receivers use DSP techniques=20 for filtering and the AGC is derived from the filtered signal. None of the= receivers=20 I have looked at have an AGC OFF facility.This means that if one of these= receivers=20 is used with ARGO or similar FFT programs a strong signal within the pass=20= band=20 will desensitise the Rx. It seems quite possible that a weak signal could=20= quite disapear. It also appears that some AGC is applied before the digital filt= er so that=20 signals within the roofing filters bandwith will also produce de-sensitisa= tion, and this=20 could be as much as 15kHz away from the tune freq. Any ideas on receivers not using DSP filtering ? Or do I look for another R1792 =20 73 Laurie G3AQC ------=_NextPart_000_07B6_01C85469.61D1AE50 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Laurie,
 
   From among my own receivers, I= find=20 that the Cubic 3280 is a very good DSP receiver AND you can shut the AGC=20 off.
For non-DSP, the newer RACALs such as the 6= 830 work=20 great and have switchable AGC.
An SLM such as the 3586 is a good choice if= all you=20 don't need an AM detector.
 
I agree with the comments on the R75 and AO= R 7030-=20 but both benefit from adding the cw filters.
 
If price is no object QST claims that the I= com=20 R-9500 is one of the best ever in terms of strong signal handling (though I=20 can't confirm this from personal experience yet).
 
73 Warren K2ORS
 
 
----- Original Message -----
lawrence mayhead
To: rsgb
Sent: Friday, January 11, 2008 1:45= =20 PM
Subject: LF: LF Receiver

I have for a long time used a Racal 1792 reciever for QRSS=20 modes on LF.
This receiver failed recently,and I have been looking for=20= a=20 replacement receiver.
This search reveals a problem most modern receive= rs=20 use DSP techniques
for filtering and the AGC is derived from the filte= red=20 signal. None of the receivers
I have looked at have an AGC OFF =20 facility.This means that if one of these receivers
is used with ARGO o= r=20 similar FFT programs a strong signal within the pass band
will desensi= tise=20 the Rx. It seems quite possible that a weak signal could quite
disapear= . It=20 also appears that some AGC is applied before the digital filter so that=20
signals within the roofing filters bandwith will also produce=20 de-sensitisation, and this
could be as much as 15kHz away from the tun= e=20 freq.
Any ideas on receivers not using DSP filtering ?
Or do I look=20= for=20 another R1792   

73 Laurie=20 G3AQC
------=_NextPart_000_07B6_01C85469.61D1AE50--