X-GM-THRID: 1234775475794570301 X-Gmail-Labels: rsgb lf Delivered-To: daveyxm@gmail.com Received: by 10.35.22.8 with SMTP id z8cs336202pyi; Thu, 26 Apr 2007 00:47:38 -0700 (PDT) Received: by 10.82.123.16 with SMTP id v16mr2682672buc.1177573658405; Thu, 26 Apr 2007 00:47:38 -0700 (PDT) Return-Path: Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mx.google.com with ESMTP id c1si3597875ugf.2007.04.26.00.47.32; Thu, 26 Apr 2007 00:47:38 -0700 (PDT) Received-SPF: neutral (google.com: 193.82.116.20 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1HgydH-00055j-1d for rs_out_1@blacksheep.org; Thu, 26 Apr 2007 08:43:15 +0100 Received: from [83.244.159.144] (helo=relay3.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1HgydG-00055a-Hf for rsgb_lf_group@blacksheep.org; Thu, 26 Apr 2007 08:43:14 +0100 Received: from imo-m23.mx.aol.com ([64.12.137.4]) by relay3.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1HgydD-0005f7-T1 for rsgb_lf_group@blacksheep.org; Thu, 26 Apr 2007 08:43:14 +0100 Received: from ColePe@aol.com by imo-m23.mx.aol.com (mail_out_v38_r9.2.) id l.c96.df089c8 (58677) for ; Thu, 26 Apr 2007 03:43:03 -0400 (EDT) From: ColePe@aol.com Message-ID: Date: Thu, 26 Apr 2007 03:43:03 EDT To: rsgb_lf_group@blacksheep.org MIME-Version: 1.0 X-Mailer: 9.0 SE for Windows sub 5022 X-Spam-Flag: NO X-Spam-Score: 0.6 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,NO_REAL_NAME=0.55 Subject: LF: FT1000MP - 500kc Content-Type: multipart/alternative; boundary="-----------------------------1177573383" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.8 required=5.0 tests=HTML_20_30,HTML_MESSAGE, NO_REAL_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 Status: O X-Status: X-Keywords: X-UID: 1956 -------------------------------1177573383 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 25/04/2007 06:45:18 Greenwich Standard Time, dk1kq@t-online.de writes: Hi Peter, here also FT1000MP and also observed lower senestivity arround 500 kc. Wonder if you have built a preamplifier in order to overcome this ? Uwe, dk1kq Hullo Uwe, Yes, I made a simple preamplifier that solved the problem of low sensitivity and removed the spurious signals from my local medium wave broadcast stations. The input circuit is a small 465 KHz I.F. transformer in a can 2 x 2 x 3.5 cm, possibly from and old transistor radio. The coils are tuned by 330pF capacitors and one of the windings has a low-Z tap. The Q of each coil is about 75 at 500KHz. I use the low-Z tap for the aerial input and the secondary winding feeds the gate of a BF244A FET amplifier with its drain directly coupled to a 2N3906 transistor emitter follower. It is actually a circuit for an LF band preselector that I published more than 25 years ago in the now defunct Short Wave Magazine. I have seen a very similar circuit for 500 KHz somewhere on the internet but can't remember where. However, any simple tuned preamp should work fine at this frequency. With the preamp in circuit I operate the FT1000MP with the IPO button 'on' and the ATT set to give a low S-meter reading on local noise picked up by the antenna. Sensitivity is now more than adequate and there is no trace of spurious on the Spectran waterfall. 73 Peter, G3JFS. -------------------------------1177573383 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
 =20
In a message dated 25/04/2007 06:45:18 Greenwich Standard Time,=20 dk1kq@t-online.de writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
Hi Peter,
 
here also FT1000MP and also observed lower senestivity= =20 arround 500 kc.
Wonder if you have built a preamplifier in order to ov= ercome=20 this ?
 
Uwe, dk1kq
Hullo Uwe,
 
Yes, I made a simple preamplifier that solved the problem of low=20 sensitivity and removed the spurious signals from my local medium wave broad= cast=20 stations.
 
The input circuit is a small 465 KHz I.F. transformer in a can 2 x 2 x=20= 3.5=20 cm, possibly from and old transistor radio.  The coils are tuned b= y=20 330pF capacitors and one of the windings has a low-Z tap.  The Q of eac= h=20 coil is about 75 at 500KHz.  I use the low-Z tap for the aerial input a= nd=20 the secondary winding feeds the gate of a BF244A FET amplifier with its= =20 drain directly coupled to a 2N3906 transistor emitter follower. It is=20 actually a circuit for an LF band preselector that I published more than 25=20 years ago in the now defunct Short Wave Magazine.  I have seen a very=20 similar circuit for 500 KHz somewhere on the internet but can't=20 remember where.  However, any simple tuned preamp should work fine= at=20 this frequency.
 
With the preamp in circuit I operate the FT1000MP with the IPO button '= on'=20 and the ATT set to give a low S-meter reading on local noise picked up by th= e=20 antenna.  Sensitivity is now more than adequate and there is no trace o= f=20 spurious on the Spectran waterfall.
 
73 Peter, G3JFS.
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