Return-Path: Received: from rly-dc08.mx.aol.com (rly-dc08.mail.aol.com [172.19.136.37]) by air-dc05.mail.aol.com (v125.7) with ESMTP id MAILINDC053-b374b03c18c132; Wed, 18 Nov 2009 04:42:55 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by rly-dc08.mx.aol.com (v125.7) with ESMTP id MAILRELAYINDC083-b374b03c18c132; Wed, 18 Nov 2009 04:42:37 -0500 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NAh2k-0000yl-L7 for rs_out_1@blacksheep.org; Wed, 18 Nov 2009 09:41:42 +0000 Received: from [83.244.159.144] (helo=relay3.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NAh2j-0000yZ-M8 for rsgb_lf_group@blacksheep.org; Wed, 18 Nov 2009 09:41:41 +0000 Received: from mtaout03-winn.ispmail.ntl.com ([81.103.221.49]) by relay3.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NAh2i-0007S1-Fx for rsgb_lf_group@blacksheep.org; Wed, 18 Nov 2009 09:41:41 +0000 Received: from know-smtpout-1.server.virginmedia.net ([62.254.123.1]) by mtaout03-winn.ispmail.ntl.com (InterMail vM.7.08.04.00 201-2186-134-20080326) with ESMTP id <20091118094135.PZDX17277.mtaout03-winn.ispmail.ntl.com@know-smtpout-1.server.virginmedia.net> for ; Wed, 18 Nov 2009 09:41:35 +0000 Received: from [81.109.247.175] (helo=jimdesk) by know-smtpout-1.server.virginmedia.net with esmtp (Exim 4.63) (envelope-from ) id 1NAh2Z-0004pC-K3 for rsgb_lf_group@blacksheep.org; Wed, 18 Nov 2009 09:41:35 +0000 From: "James Cowburn" To: References: <572081.7375.qm@web28101.mail.ukl.yahoo.com> Date: Wed, 18 Nov 2009 09:41:29 -0000 Message-ID: <02b601ca6833$4e59f6e0$0517aac0@jimdesk> MIME-Version: 1.0 X-Mailer: Microsoft Office Outlook 11 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3350 In-Reply-To: <572081.7375.qm@web28101.mail.ukl.yahoo.com> Thread-Index: AcpoMWrrCm+VoCmASxyDQaVTv/2VgAAAS2hg X-Cloudmark-Analysis: v=1.0 c=1 a=F3M5lZpKAAAA:8 a=MDZQaXdsAAAA:8 a=8RloEfZUAAAA:8 a=CjxXgO3LAAAA:8 a=XzrfCR61MmQPtzHM4p8A:9 a=C9PNA2NZDH64AnnVdv8A:7 a=Sw0b4iNCz2W10J1RAoQnxkx5yA0A:4 a=wk6s2zzMB60A:10 a=nhn505YfawQA:10 a=O58u2wXj750A:10 a=3Sf-kTeUB8AL-r8b:21 a=j5Cx0pzmvb2eDnVw:21 a=SSmOFEACAAAA:8 a=KDqohqnSO_qWppd6dAAA:9 a=0kc6OIgKMUe8DFH4fzQA:7 a=X_pNSmixoe4HPCcyoYwUHxb_nPsA:4 a=Yw4auK_1PsSwxIDI:21 a=zBjAJyCjIzCg_Cgx:21 X-Spam-Score: 0.3 (/) X-Spam-Report: autolearn=disabled,HTML_FONT_BIG=0.256,HTML_MESSAGE=0.001 Subject: RE: LF: Re: G7NKS sidebands Content-Type: multipart/alternative; boundary="----=_NextPart_000_02B7_01CA6833.4E59F6E0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.0 required=5.0 tests=HTML_30_40, HTML_FONTCOLOR_UNKNOWN,HTML_FONT_BIG,HTML_MESSAGE 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 ------=_NextPart_000_02B7_01CA6833.4E59F6E0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Hi Pete The Rig only gets overly hot on powers over abt 20 watt output and 20%+ duty cycle (not to be unexpected given the operation at or beyond the limits of design). When I run it around 10 to 15 watts and on 10% duty it stays just lightly warm so as far as I can tell there is no discontinuity or paradox in the ouput/duty/warming matrix! The sidebands will no doubt be still there, just beyond the limit of detection With best regards Jim Dr. James Cowburn _____ From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of M0FMT Sent: 18 November 2009 09:27 To: rsgb_lf_group@blacksheep.org Subject: Re: LF: Re: G7NKS sidebands Hi LF I think the issue is intermodulation products caused by over driving the the linear RF stages of the TX into distortion because when Jim reduces drive the sidebands petty well disappear at this range. These observation is based upon test carried out yesterday. There is another issue Jim seems to have which is that his PA grossly over heats (I think I am right) when he reduces drive and that shouldn't happen. For modulation to take place the output of the modulator has to be mixed (hetrodyned) with the RF signal. In this case I am guessing that the carrier is modulated by noise (50c/s say) in the non linear (over driven linear RF stages) in the TX driver or output. The fact the PA over heats on reduced drive suggests to me the bias on the PA transistors is being altered by changes to the drive anther indication that the TX output may not be entirely linear --- On Wed, 18/11/09, James Moritz wrote: From: James Moritz Subject: LF: Re: G7NKS sidebands To: rsgb_lf_group@blacksheep.org Date: Wednesday, 18 November, 2009, 1:13 Dear Jim LF Group, Looking at the sidebands on the G7NKS WSPR signals, mains hum or other noise by itself is not a sufficient explanation of what is seen. Simply adding 50Hz, 150Hz, etc. noise into the PC audio channel, then feeding the result into an SSB TX would give unwanted CW at frequencies offset from the SSB carrier frequency by +/-50Hz, 150Hz and so on, i.e. with the carrier "dial frequency" at 502.4kHz, unmodulated carriers would appear at 502.45kHz, 502.55kHz and so on, in addition to the WSPR signal at around 503.9kHz. However, these would probably largely be removed by the SSB filter in the rig. Instead, we see unwanted sidebands offset from the wanted WSPR signal frequency by +/- 50Hz, 150Hz, with identical modulation to the wanted signal. This requires some sort of non-linear process to cause the intermodulation between the presumed mains noise and the WSPR signal somewhere in the TX chain. One possibility is that intermodulation occurs in the PA. Jim's description suggests that he is persuading the HF PA in the IC735 to produce output at 500k. At this frequency, the PA linearity may well be poor due to the impedance matching, coupling, decoupling and feedback components in the PA being wrong for the frequency, and high flux densities occuring in ferrite components due to the low operating frequency. But this wouldn't explain why Jim also gets multiple received signals from a strong station with a clean signal, which implies some identical noise source and distortion in the receive path. It would also mean the mains noise getting through the filtering in the rig somehow. A possibility that would explain the unwanted sidebands appearing on both TX and RX signals is if one of the oscillators in the system has mains noise sidebands. The sound card clock seems unlikely, since this is just a simple crystal oscillator. I see the IC735 has some sort of multi-loop PLL synthesiser, which would certainly be prone to this type of spurious signal, since any kind of mains noise getting in would modulate the VCO frequencies, and would probably be the same on transmit and receive. This could be checked by receiving a clean carrier somewhere around 500kHz, and examining the audio output using Spec Lab or Argo or similar to see if 50Hz and 150Hz sidebands are present on the received audio tone. Cheers, Jim Moritz 73 de M0BMU ----- Original Message ----- From: "James Cowburn" > To: > Sent: Monday, November 16, 2009 8:26 PM Subject: LF: rule #2 - assumption is the brother of all foul ups > LF > > > > Sidebands are back! I think its caused by my TX getting hot and bothered by > struggling at 500. From cold it txs 50 watts but this soon drops back to > around 35, and the sidebands appear. My sigs are better so having the txfr > outside the shack and at the antenna is a vast improvement, but I now need > to work on the cooling. ------=_NextPart_000_02B7_01CA6833.4E59F6E0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Hi Pete

 

The Rig only ge= ts overly hot on powers over abt 20 watt output and 20%+ duty cycle (not to be unexpected give= n the operation at or beyond the limits of design).  When I run it arou= nd 10 to 15 watts and on 10% duty it stays just lightly warm so as far as I can te= ll there is no discontinuity or paradox in the ouput/duty/warming matrix! =

 

The sidebands= will no doubt be still there, just beyond the limit of detection

 

 

 

With best regar= ds

 

 

Jim=

 

 

Dr. James Cowbu= rn

From: owner-rsgb_lf_group@blac= ksheep.org [mailto:owner-= rsgb_lf_group@blacksheep.org] On Behalf Of M0FMT
Sent: 18 November 2009= 09:27
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: Re: G7= NKS sidebands

 

Hi LF

 

I think the issue is intermodulation pro= ducts caused by over driving the the linear RF stages of the TX into distortion&n= bsp;because when Jim reduces drive the sidebands petty well disappear at this ra= nge. These observation is based upon test carried out yesterday. There is= another issue Jim seems to have which is that his PA grossly over heats (I= think I am right) when he reduces drive and that shouldn't happen. For modulati= on to take place the output of the modulator has to be mixed (hetrody= ned) with the RF signal. In this case I am guessing that the carrier is modula= ted by noise (50c/s say) in the non linear (over driven linear RF stages)= in the TX driver or output.

The fact the PA over heats on reduced dr= ive suggests to me the bias on the PA transistors is being altered by changes to= the drive anther indication that the TX output may not be entirely linear

--- On Wed, 18/11/09, James Mori= tz <james.moritz@btopenworld= .com> wrote:


From: James Moritz <james.moritz@btopenworld.com>
Subject: LF: Re: G7NKS sidebands
To: rsgb_lf_group@blacksheep.org
Date: Wednesday, 18 November, 2009, 1:13

Dear Jim= LF Group,

Looking at the sidebands on the G7NKS WSPR signals, mains hum or oth= er noise by itself is not a sufficient explanation of what is seen. Simply ad= ding 50Hz, 150Hz, etc. noise into the PC audio channel, then feeding the= result into an SSB TX would give unwanted CW at frequencies offset from the= SSB carrier frequency by +/-50Hz, 150Hz and so on, i.e. with the carrier "dial frequency" at 502.4kHz, unmodulated carriers would= appear at 502.45kHz, 502.55kHz and so on, in addition to the WSPR signal at ar= ound 503.9kHz. However, these would probably largely be removed by the SS= B filter in the rig. Instead, we see unwanted sidebands offset from the wante= d WSPR signal frequency by +/- 50Hz, 150Hz, with identical modulation to th= e wanted signal. This requires some sort of non-linear process to cause the intermodulation between the presumed mains noise and the WSPR signal somewhere in the TX chain.

One possibility is that intermodulation occurs in the PA. Jim's desc= ription suggests that he is persuading the HF PA in the IC735 to produce out= put at 500k. At this frequency, the PA linearity may well be poor due to th= e impedance matching, coupling, decoupling and feedback components in= the PA being wrong for the frequency, and high flux densities occuring in= ferrite components due to the low operating frequency. But this wouldn't exp= lain why Jim also gets multiple received signals from a strong station with= a clean signal, which implies some identical noise source and distortion in= the receive path. It would also mean the mains noise getting through the filtering in the rig somehow.

A possibility that would explain the unwanted sidebands appearing on= both TX and RX signals is if one of the oscillators in the system has mains= noise sidebands. The sound card clock seems unlikely, since this is just= a simple crystal oscillator. I see the IC735 has some sort of multi-loop PLL synthesiser, which would certainly be prone to this type of spurious= signal, since any kind of mains noise getting in would modulate the VCO freq= uencies, and would probably be the same on transmit and receive. This could= be checked by receiving a clean carrier somewhere around 500kHz, and examining= the audio output using Spec Lab or Argo or similar to see if 50Hz and 150Hz si= debands are present on the received audio tone.

Cheers, Jim Moritz
73 de M0BMU


----- Original Message ----- From: "James Cowburn" <james.cowburn@virgin.net>
To: <rsgb_lf_group@blacks= heep.org>
Sent: Monday, November 16, 2009 8:26 PM
Subject: LF: rule #2 - assumption is the brother of all foul ups


> LF
>
>
>
> Sidebands are back!  I think its caused by my TX getting= hot and bothered by
> struggling at 500.  From cold it txs 50 watts but this soo= n drops back to
> around 35, and the sidebands appear.  My sigs are better= so having the txfr
> outside the shack and at the antenna is a vast improvement, but= I now need
> to work on the cooling.

 

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