Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mb01.r1000.mx.aol.com (Internet Inbound) with ESMTP id 2279D380000B3; Wed, 11 Jan 2012 09:49:39 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1RkzTc-0002HK-R6 for rs_out_1@blacksheep.org; Wed, 11 Jan 2012 14:48:32 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1RkzTc-0002HB-78 for rsgb_lf_group@blacksheep.org; Wed, 11 Jan 2012 14:48:32 +0000 Received: from relay.uni-heidelberg.de ([129.206.100.212]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1RkzTa-0000oi-Sf for rsgb_lf_group@blacksheep.org; Wed, 11 Jan 2012 14:48:32 +0000 Received: from freitag.iup.uni-heidelberg.de (freitag.iup.uni-heidelberg.de [129.206.29.204]) by relay.uni-heidelberg.de (8.14.1/8.14.1) with ESMTP id q0BEmUtv010242 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Wed, 11 Jan 2012 15:48:30 +0100 Received: from [129.206.22.206] (pc206.iup.uni-heidelberg.de [129.206.22.206]) by freitag.iup.uni-heidelberg.de (8.12.11.20060308/8.11.2) with ESMTP id q0BEmUGj011605 for ; Wed, 11 Jan 2012 15:48:30 +0100 Message-ID: <4F0DA134.2070004@iup.uni-heidelberg.de> Date: Wed, 11 Jan 2012 15:48:20 +0100 From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <4F0CC679.2010206@charter.net>,<4F0D81E5.4010602@iup.uni-heidelberg.de> In-Reply-To: X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,RATWARE_GECKO_BUILD=1.426 Subject: Re: LF: RE: QRP 1W /PA circuit Content-Type: multipart/alternative; boundary="------------050008060206030701090602" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_20_30,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-global-disposition: G X-AOL-SCOLL-SCORE: 1:2:451235648:93952408 X-AOL-SCOLL-URL_COUNT: 3 x-aol-sid: 3039ac1d60154f0da1831744 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. --------------050008060206030701090602 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by relay.uni-heidelberg.de id q0BEmUtv010242 Hi Rik, The driver is a IXDD414CI=20 whic= h=20 drives the 4 FETs by using a ferrite core (Al=3D4000, OD=3D20mm). Primary= 4=20 turns in series with 2 Ohm and 10uF. Then there are 4 secondary widings=20 with 5 turns each. Each FET has a 1 Ohm Gate resistor in front. This is=20 to prevent overswing at turn on/off. Using a ICL7667, the gate resistors=20 are not necessary (but the 7667 cannot drive the 4 FETs with sufficient=20 switching times) but the IXDD414 is another world (i use it in a 300W PA=20 at 10 MHz). I can make a drawing if necessary. BTW trying the ferrite core principle instead of the IR2113 (which has=20 problems at 137 kHz and 4 nF input C on the H side, at least at high=20 operating temperatures and after some hours of operation) is an idea of=20 Markus/DF6NM. The Gates are driven very securely by that method. Also it is much=20 easier to configurate and only needs a single low-side driver for that=20 "complex" arrangement. Another advantage is that once a FET is blown up,=20 making a short cut between Gate and Source, it also prevents the other=20 FETs to get switched on, so it may help to protect the other FETs. A=20 poly switch fuse in series ( i like them ;-) ) helps to pretect the=20 driver from overheating when operating on that short cut. 73, Stefan/DK7FC Am 11.01.2012 15:27, schrieb Rik Strobbe: > Hi Stefan, > how do you drive the H-bridge amp ? > 73, Rik ON7YD - OR7T > -----------------------------------------------------------------------= - > *Van:* owner-rsgb_lf_group@blacksheep.org=20 > [owner-rsgb_lf_group@blacksheep.org] namens Stefan Sch=E4fer=20 > [Stefan.Schaefer@iup.uni-heidelberg.de] > *Verzonden:* woensdag 11 januari 2012 13:34 > *Aan:* rsgb_lf_group@blacksheep.org > *Onderwerp:* LF: QRP 1W /PA circuit > > LF, > > Last night i shot my PA again :-( No replacement FETs were available=20 > so i had to stay quite during the night. Replacement parts are ordered=20 > now and will arrive tomorrow :-) > > During that time i will run a *LF beacon on 136.172 kHz running _1W TX=20 > power_ in DFCW-90*, starting in the afternoon. If someone can receive=20 > that weak *QRPP* signal, then a* report is very apprechiated :-)* > > Also i will do some optimisations on my recently posted PA output=20 > stage=20 > (http://dl.dropbox.com/u/19882028/LF/DK7FC_137kHz_TX_antenna_and_PA_sch= ematic.jpg),=20 > just in case someone wants to build a similar design and is interested=20 > in general: > > -R=3D 100 Ohm/2W (In series with C, across Drain-Source) > -C=3D 220pF/WIMA FKP-1 2kV (In series with R, across Drain-Source) > -MOSFET: The IRFP460=20 > will=20 > be replaced by a SPW20N60C3=20 > :-) > > 73, Stefan/DK7FC --------------050008060206030701090602 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Hi Rik,

The driver is a IXDD414CI which drives the 4 FETs by using a ferrite core (Al=4000, OD=20mm). Primary 4 turns in series with 2 Ohm and 10uF. Then there are 4 secondary widings with 5 turns each. Each FET has a 1 Ohm Gate resistor in front. This is to prevent overswing at turn on/off. Using a ICL7667, the gate resistors are not necessary (but the 7667 cannot drive the 4 FETs with sufficient switching times) but the IXDD414 is another world (i use it in a 300W PA at 10 MHz).
I can make a drawing if necessary.
BTW trying the ferrite core principle instead of the IR2113 (which has problems at 137 kHz and 4 nF input C on the H side, at least at high operating temperatures and after some hours of operation) is an idea of Markus/DF6NM.

The Gates are driven very securely by that method. Also it is much easier to configurate and only needs a single low-side driver for that "complex" arrangement. Another advantage is that once a FET is blown up, making a short cut between Gate and Source, it also prevents the other FETs to get switched on, so it may help to protect the other FETs. A poly switch fuse in series ( i like them ;-) ) helps to pretect the driver from overheating when operating on that short cut.

73, Stefan/DK7FC

Am 11.01.2012 15:27, schrieb Rik Strobbe:
Hi Stefan,
 
how do you drive the H-bridge amp ?
 
73, Rik  ON7YD - OR7T
 
Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens Stefan Schäfer [Stefan.Schaefer@iup.uni-heidelberg.de]
Verzonden: woensdag 11 januari 2012 13:34
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: LF: QRP 1W /PA circuit

LF,

Last night i shot my PA again :-( No replacement FETs were available so i had to stay quite during the night. Replacement parts are ordered now and will arrive tomorrow :-)

During that time i will run a LF beacon on 136.172 kHz running 1W TX power in DFCW-90, starting in the afternoon. If someone can receive that weak QRPP signal, then a report is very apprechiated :-)

Also i will do some optimisations on my recently posted PA output stage (http://dl.dropbox.com/u/19882028/LF/DK7FC_137kHz_TX_antenna_and_PA_schematic.jpg), just in case someone wants to build a similar design and is interested in general:

-R= 100 Ohm/2W (In series with C, across  Drain-Source)
-C= 220pF/WIMA FKP-1 2kV  (In series with R, across Drain-Source)
-MOSFET: The IRFP460 will be replaced by a SPW20N60C3 :-)

73, Stefan/DK7FC
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