Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by klubnl.pl (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id vBTCg5Yi009591 for ; Fri, 29 Dec 2017 13:42:08 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1eUtuY-0007AV-SB for rs_out_1@blacksheep.org; Fri, 29 Dec 2017 12:37:18 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1eUtuY-0007AM-2l for rsgb_lf_group@blacksheep.org; Fri, 29 Dec 2017 12:37:18 +0000 Received: from omr-a016e.mx.aol.com ([204.29.186.65]) by relay1.thorcom.net with esmtps (TLSv1:DHE-RSA-AES256-SHA:256) (Exim 4.89) (envelope-from ) id 1eUtuU-0002BX-Sb for rsgb_lf_group@blacksheep.org; Fri, 29 Dec 2017 12:37:16 +0000 Received: from mtaomg-mcd02.mx.aol.com (mtaomg-mcd02.mx.aol.com [172.26.223.208]) by omr-a016e.mx.aol.com (Outbound Mail Relay) with ESMTP id 021413800084 for ; Fri, 29 Dec 2017 07:37:13 -0500 (EST) Received: from core-ace03c.mail.aol.com (core-ace03.mail.aol.com [172.27.23.3]) by mtaomg-mcd02.mx.aol.com (OMAG/Core Interface) with ESMTP id C1CDF38000082 for ; Fri, 29 Dec 2017 07:37:12 -0500 (EST) Received: from 188.194.222.230 by webjas-vad074.srv.aolmail.net (10.96.35.77) with HTTP (WebMailUI); Fri, 29 Dec 2017 07:37:12 -0500 Date: Fri, 29 Dec 2017 07:37:12 -0500 From: Markus Vester To: rsgb_lf_group@blacksheep.org Message-Id: <160a246ba92-171d-5731@webjas-vad074.srv.aolmail.net> In-Reply-To: MIME-Version: 1.0 X-MB-Message-Source: WebUI X-MB-Message-Type: User X-Mailer: JAS STD X-Originating-IP: [188.194.222.230] x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20150623; t=1514551032; bh=EMG4G0aQw0mkLsh5IlZeLVoWy8hcdunt3Jqv4OnUFYw=; h=From:To:Subject:Message-Id:Date:MIME-Version:Content-Type; b=ZpFJ270tILYjmpw55qVZA/y6vHN3tu/q8yv5AxVVKbJ0p0zHeY/mXndHlGi/G7HFt HrNf8Thu+TWDRk1Ph826kzdFcK4lKXnXGhikIsg6CXYla8oBuwKaT0OVJWydGyZkOV eRpJX5W/088xLm0GSpnch/oZkGqivdfBmKgtdctM= x-aol-sid: 3039ac1adfd05a4636f8136b X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Hi Paul, adding in my 0.5 cent's worth: Could the scope "blurring " be caused by a high-frequency rather than low-frequency oscillation? At high frequencies, the drain will see the stray inductance of the transformer (or self-resonances at VHF), in parallel to the non-linear output capacitance of the device. This might encourage transient ringing or even parasitic oscillations every time the transistor comes out of saturation. Have you tried a simple "snubber" network (e.g. 1 nF + 10 ohms) at the drain? [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (markusvester[at]aol.com) 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: da9a90c67b7e22f6718c156d8d99c1a4 Subject: Re: R: Re: LF: TXing 2200m WSPR Content-Type: multipart/alternative; boundary="----=_Part_28831_849682823.1514551032466" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=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 ------=_Part_28831_849682823.1514551032466 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Hi Paul, adding in my 0.5 cent's worth: Could the scope "blurring " be caused by a h= igh-frequency rather than low-frequency oscillation? At high frequencies, t= he drain will see the stray inductance of the transformer (or self-resonanc= es at VHF), in parallel to the non-linear output capacitance of the device.= This might encourage transient ringing or even parasitic oscillations ever= y time the transistor comes out of saturation. Have you tried a simple "snu= bber" network (e.g. 1 nF + 10 ohms) at the drain? Best 73, Markus (DF6NM) -----Urspr=C3=BCngliche Mitteilung-----=20 Von: N1BUG An: rsgb_lf_group Verschickt: Fr, 29. Dez 2017 12:57 Betreff: Re: R: Re: LF: TXing 2200m WSPR Hi Chris, At PS side of the choke, no RF behaving or misbehaving. At output transformer side of the choke, mainly negative-going=20 pulses which become distorted similarly to the output when misbehaving. Drain waveform is like a sine wave with regular shaped positive=20 half, negative half is double peak. When misbehaving, same basic=20 shape but blurry just as the RF output is... looks as if amplitude=20 constantly changes from cycle to cycle, as though modulated by a=20 lower frequency. Gate waveform almost a pure sine wave (remember this is a class=20 AB/B/C amp), develops amplitude blur or modulation when misbehaving. My "gut" tells me this amp is oscillating at a frequency well below=20 the band (maybe at VLF) but only when feeding the antenna. Perhaps=20 the fact the antenna is a very reactive load at VLF sets it off? I=20 don't know why it would happen at different RF power levels with 13V=20 / 19V PSU unless it is proportional to current somewhere... I'm about ready to take this amp down to the train track and strap=20 it on a rail... might be rather satisfying. ;-) Paul N1BUG On 12/29/2017 06:26 AM, Chris Wilson wrote: >=20 >=20 > Hello N1BUG, >=20 >=20 > What does the scope show if you look at each side of the choke in the > PA? I did some tests ages ago using the stacked chip caps on the PA > side of the choke compared to conventional leaded caps and the > difference was marked. I would certainly try a proper dust iron core > for the choke, ferrite can't be right... I don't use a LPF after the > U3S but my amp is "Class D" and is happy with being driven with square > waves. >=20 > Friday, December 29, 2017, 11:13:03 AM, you wrote: >=20 >> One final thing. >=20 >> Thought maybe something in the antenna was breaking down (arcing or >> corona), so made another check: >=20 >> I now have the capability to run the PA on 13V or 19V. At 19V I can >> make more power into the antenna before the signal goes dirty, >> compared to 13V. RF power is RF power. If it was something failing >> in the antenna system I think it should happen at the same RF power, >> no matter what DC supply voltage I use on the PA... >=20 >> Paul ------=_Part_28831_849682823.1514551032466 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable
Hi Paul,

adding in my 0.5 cent's wor= th: Could the scope "blurring " be caused by a high-frequency rather t= han low-frequency oscillation? At high frequencies, the drain will see= the stray inductance of the transformer (or self-resonances at VHF), = in parallel to the non-linear output capacitance of the device. This m= ight encourage transient ringing or even parasitic oscillations every&= nbsp;time the transistor comes out of saturation. Have you tried = a simple "snubber" network (e.g. 1 nF + 10 ohms) at the drain?
Best 73,
Markus (DF6NM)


-----U= rspr=C3=BCngliche Mitteilung-----
Von: N1BUG <paul@n1bu= g.com>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.or= g>
Verschickt: Fr, 29. Dez 2017 12:57
Be= treff: Re: R: Re: LF: TXing 2200m WSPR

Hi Chris,

At PS side of the choke, no R= F behaving or misbehaving.

At output trans= former side of the choke, mainly negative-going
pulses whi= ch become distorted similarly to the output when misbehaving.

Drain waveform is like a sine wave with regular shaped = positive
half, negative half is double peak. When misbehav= ing, same basic
shape but blurry just as the RF output is.= .. looks as if amplitude
constantly changes from cycle to = cycle, as though modulated by a
lower frequency.

Gate waveform almost a pure sine wave (remember thi= s is a class
AB/B/C amp), develops amplitude blur or modul= ation when misbehaving.

My "gut" tells me = this amp is oscillating at a frequency well below
the band= (maybe at VLF) but only when feeding the antenna. Perhaps
the fact the antenna is a very reactive load at VLF sets it off? I
don't know why it would happen at different RF power levels with = 13V
/ 19V PSU unless it is proportional to current somewhe= re...

I'm about ready to take this amp dow= n to the train track and strap
it on a rail... might be ra= ther satisfying. ;-)

Paul N1BUG



On 12/29/2017 06:2= 6 AM, Chris Wilson wrote:
>
>
> Hello N1BUG,
>
> > What does the scope show if you look at each side of th= e choke in the
> PA? I did some tests ages ago using= the stacked chip caps on the PA
> side of the choke = compared to conventional leaded caps and the
> diff= erence was marked. I would certainly try a proper dust iron core
> for the choke, ferrite can't be right... I don't use a LPF= after the
> U3S but my amp is "Class D" and is happy wi= th being driven with square
> waves.
>= ;
> Friday, December 29, 2017, 11:13:03 AM, you wrote:<= br abp=3D"2758">>
>> One final thing.
>
>> Thought maybe something in the antenna = was breaking down (arcing or
>> corona), so made anot= her check:
>
>> I now have the ca= pability to run the PA on 13V or 19V. At 19V I can
>>= make more power into the antenna before the signal goes dirty,
>> compared to 13V. RF power is RF power. If it was something fa= iling
>> in the antenna system I think it should happ= en at the same RF power,
>> no matter what DC supply = voltage I use on the PA...
>
>> P= aul

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