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 w09BBC4n026455 for ; Tue, 9 Jan 2018 12:11:15 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1eYrdS-0006P1-JY for rs_out_1@blacksheep.org; Tue, 09 Jan 2018 11:00:02 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1eYrdS-0006Or-9t for rsgb_lf_group@blacksheep.org; Tue, 09 Jan 2018 11:00:02 +0000 Received: from mout.perfora.net ([74.208.4.194]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1eYrdP-0004dB-FA for rsgb_lf_group@blacksheep.org; Tue, 09 Jan 2018 11:00:01 +0000 Received: from [192.168.1.127] ([72.224.254.201]) by mrelay.perfora.net (mreueus002 [74.208.5.2]) with ESMTPA (Nemesis) id 0Mhk4D-1eDmPo3oNH-00Mqf9 for ; Tue, 09 Jan 2018 11:59:56 +0100 To: rsgb_lf_group@blacksheep.org References: <186c1122-88cf-cc41-72f5-adaee6b25377@n1bug.com> From: N1BUG Message-ID: <92a4a7af-252b-0b78-2ed5-b4b32a186211@n1bug.com> Date: Tue, 9 Jan 2018 05:59:55 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Provags-ID: V03:K0:2fLrnbLqKx59FQEYM7Oy92BmPWx33Z2iatkZ3Pl4pJNi9eEi1/k HhTrDXd/ObGrErKUBFWOJ8buO97wfPQ/J3Y3Pee0w0M3ivgMlAvOn3+IRRQANOYohA2csze iq3gg+dKCrGQRyINDsAm7OCkvZckK+DUSSG4Kvvfk7b7rpLPijBCVJ1XYohJahnC+gtgVek 3cgSrP+GsC1QomvCn5PVQ== X-UI-Out-Filterresults: notjunk:1;V01:K0:lFC0RyajMfM=:5joB1LAY+hSKGycNQoiruO ZlyvX+zMQfvFPbfzI/95Ei6J6iKuZ5kCEHPk2cxjOxoYpU4cYAO0S/bFFxWZUnWEqtD05zx8e eryrPp/DDymfCpgiluDCLDDe5xwoXtzoMcxT3EqvOJMrVM7rkj31wP1JUMg8QxvJRV2yD8g3j z3ng8V1kkm4CSDDTY3z/w4Zaw60+wDmrxhkz5BUf8F7HgW56iVOPXOEbjArDqay8fs19ty+TI ojzF4b2FquVr3UiHKgeoDci6W+ZNpz5GjDlCPbAUaBgoEplrC3HKou7DV5q71MHuMRHvG8EIy rII1lGiJtISJa8rLVwCknHao4I05PdEGtpyAPirOD5S+JvZe3rxgNc1dbmXyeQt4EQInH0uYD 9M5xtiJ5ZCjbNxOFxNWKP2qCzaTi5k3UvJg5ijT7ROD9e+97D06T6GxMZ8zqBGCfDk1fMn2Ex ysXocmxf/fMGQNE6XhDZDDGKrOnR/w7FXYFIx+/ZaAAy+vtMHvabpvUMNegeliYwLqzxM9c82 xJSjFxv3tdjCQBBwxLVAjyOyyGaDijy/wGOqvHdEhoTbj1GC5PFoxIeaHhq2/m849/3eCeTrj uYf2benThHWl9Qe4jnHRxV/Y1eSdyj6+FAYyDsX4sJehON2vFgXq8grHrtM76fLzty8m6eITn pvXKAAhVh2F5UC2XOJNrPE/NG+O/XftLt2W+YnhuTMSqAd9kijD0wcEYb4H/7NaKeQYbGHylU Qiof9g7wkNyh0gM6qItHfEks52MBgyQDaWrWE/OiTN4K2Q0T2QZk0CIcCcI= X-Spam-Score: 1.1 (+) 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 David, That's an idea I haven't tried yet. I had tried a series C and R from gate to ground with no benefit but had not tried drain to gate. I'm really not sure where it is oscillating. I am unable to determine that from what can only be described as utter chaos on the scope trace. [...] Content analysis details: (1.1 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 HTML_MESSAGE BODY: HTML included in message 1.1 MIME_HTML_ONLY BODY: Message only has text/html MIME parts X-Scan-Signature: 4d97240a623a26620214cd27feaa9f71 Subject: Re: LF: Great conditions and first QSO Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 8bit 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_FONT_BIG, HTML_MESSAGE,MIME_HTML_ONLY 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

Hi David,

That's an idea I haven't tried yet. I had tried a series C and R from gate to ground with no benefit but had not tried drain to gate.

I'm really not sure where it is oscillating. I am unable to determine that from what can only be described as utter chaos on the scope trace.

With some amount of luck I will have a better behaved PA on MF soon. LF is another story. I do have a plan but not a quick fix.

73,
Paul


On 01/08/2018 11:27 AM, David Bowman wrote:
Hi Paul.

Idea number ????      If your amplifier is oscillating above MF, then you may be able to tame it by using a series capacitor and resistor between drain and gate. This will apply frequency dependent negative feedback which should stop the oscillation. (Not ideal as it shouldn't oscillate anyway...but a likely fix)

Values are debatable, but 220R (1W) and 1000pF would be a place to start.

73

David

On Sun, Jan 7, 2018 at 12:19 PM, N1BUG <paul@n1bug.com> wrote:
Congratulations to 2E0ILY, G0LUJ, EB8ARZ/2, K3RWR, and WA3TTS/2 for the great trans-Atlantic work last night! Well done all.

After more than a year working toward it, I made my first two-way LF QSO with K3RWR. I was proud of myself for convincing the amplifier to put 16 watts into the antenna without any apparent funny business. Shortly after, while trying to set up on WSPR for the night, the amplifier took off and blew another FET. I then decided it was a good night for sleeping. :-)

73,
Paul N1BUG