Return-Path: Received: (qmail 72156 invoked from network); 23 Jan 2004 08:02:26 -0000 Received: from unknown (HELO ptb-mxscan02.plus.net) (212.159.14.236) by ptb-mailstore02.plus.net with SMTP; 23 Jan 2004 08:02:26 -0000 Received: (qmail 55327 invoked from network); 23 Jan 2004 08:02:26 -0000 X-Filtered-by: Plusnet (hmail v1.01) X-Spam-detection-level: 11 X-Priority: 3 X-MSMail-Priority: Normal Received: from ptb-mxcore02.plus.net (212.159.14.216) by ptb-mxscan02.plus.net with SMTP; 23 Jan 2004 08:02:24 -0000 Received: from post.thorcom.com ([193.82.116.20]) by ptb-mxcore02.plus.net with esmtp (Exim) id 1AjwGm-000EHN-NG for dave@picks.force9.co.uk; Fri, 23 Jan 2004 08:02:24 +0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-Fake-Domain: majordom Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1AjwG0-0005lC-Lh for rs_out@blacksheep.org; Fri, 23 Jan 2004 08:01:36 +0000 Received: from [134.58.240.41] (helo=nibbel.kulnet.kuleuven.ac.be) by post.thorcom.com with esmtp (Exim 4.14) id 1AjwFz-0005kw-Sa for rsgb_lf_group@blacksheep.org; Fri, 23 Jan 2004 08:01:35 +0000 Received: from localhost (localhost [127.0.0.1]) by nibbel.kulnet.kuleuven.ac.be (Postfix) with ESMTP id A74A94B7FC for ; Fri, 23 Jan 2004 09:01:05 +0100 (CET) Received: from antonius.kulnet.kuleuven.ac.be (antonius.kulnet.kuleuven.ac.be [134.58.240.73]) by nibbel.kulnet.kuleuven.ac.be (Postfix) with ESMTP id 0FA1C4B4FA for ; Fri, 23 Jan 2004 09:01:05 +0100 (CET) X-Fake-Domain: dell-rik.fys.kuleuven.ac.be Received: from dell-rik.fys.kuleuven.ac.be (pc-10-33-165-177.fys.kuleuven.ac.be [10.33.165.177]) by antonius.kulnet.kuleuven.ac.be (Postfix) with ESMTP id CB2794C0D1 for ; Fri, 23 Jan 2004 09:01:04 +0100 (CET) Message-ID: <5.1.0.14.0.20040123085347.00b7cc68@u0019445.kuleuven.be> X-Sender: u0019445@u0019445.kuleuven.be X-Mailer: QUALCOMM Windows Eudora Version 5.1 Date: Fri, 23 Jan 2004 09:03:58 +0100 To: rsgb_lf_group@blacksheep.org From: "Rik Strobbe" In-reply-to: <001401c3e13b$36201c60$2102000a@ibm> References: <000c01c3e02e$600a21a0$01eafc3e@l8p8y6> <001501c3e058$ba617980$2102000a@ibm> <002501c3e121$12a54fe0$2102000a@ibm> MIME-Version: 1.0 X-Virus-Scanned: by KULeuven Antivirus Cluster Subject: Re: LF: more on my 'nasty'136kHz project............. Content-Type: text/html; charset=windows-1252 X-Spam-Checker-Version: SpamAssassin 2.60 (1.212-2003-09-23-exp) on post.thorcom.com X-Spam-Status: No, hits=0.0 required=5.0 tests=HTML_MESSAGE autolearn=no version=2.60 X-SA-Exim-Scanned: Yes Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-PN-SPAMFiltered: yes X-Spam-Rating: 1 Content-transfer-encoding: 8bit Hello Dick,

I get +17dBm out on 137kHz now.
There are a lot of harmonics in the (unfiltered) output; especially the 3f, 5f, 7f etc.

So, at least I am producing a signal on 137kHz (and maaaaaaaaaaaany other freqs) now.

At this point I am not sure what to do.....filtering or not??
I suppose I get these harmonics again in later (driver) stages so, maybe better to
do it at the end..........

No need to filter the drive signal if you are using a class-D amplifier (in fact it is best to drive a class-D amplifier with a quare wave).
A 2 or 3 stage low-pass filter at the PA output will get rid of the harmonics, a high-Q antenna will even improve that.

How to key is the next question.
I want to leave the VFO on all the time for better stability.
The 4060 will be switched off in RX situation, to aviod having a signal on 137kHz,
and in my receiver blocking the RX..........
I did some tests with the keying circuit used by OM2TW and DF3LP/DJ1ZB in their designs
using 2 stages with BC549, from which the first one is switched in its emitter.
However, this did not work fine.
I was able to key, but the output level was much lower then it's input, and the level of
harmonics etc where worse, compaired to the input signal of the circuit.

Best thing to do is to key the PA somewhere. Dave (G3YXM) has a nice design that provides really "soft keying". I do key a G3YXM-like PA at the input and have had any complaints about key clicks so far.

73, Rik ON7YD