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Re: LF: QRP 1W /PA circuit

To: [email protected]
Subject: Re: LF: QRP 1W /PA circuit
From: Stefan Schäfer <[email protected]>
Date: Wed, 11 Jan 2012 15:02:22 +0100
In-reply-to: <CABP+t7Y47ePqNug_tWozoBVux9MJKRd0gyWS-aNLsqnMndoWfQ@mail.gmail.com>
References: <CAA8k23Qqo4ZagVGLdEiUqGSU-HL_XNpues+rPAr7NwOhiyd1zQ@mail.gmail.com> <[email protected]> <[email protected]> <CABP+t7Y47ePqNug_tWozoBVux9MJKRd0gyWS-aNLsqnMndoWfQ@mail.gmail.com>
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Hi Doug,

Thank you for your continued interest :-)

I enabled SpecLab's "beacon mode" so it will run endless until i stop. And i will stop when the new FETs arrived here :-) However i see no chance at all that you will receive anything at all, not even in DFCW-900000000000000 ;-). I'm transmitting 1W TX power, not 1W ERP!

Iceland may be the best DX to be expected, if conds are good and QRM is low.

Back soon! The new FETs have excellent data: Higher VDS, lower Rdson, lower input C, faster switching times. The recovery times and dv/dt are much better too (not really a FREDFET though) so i will keep the RC circuit...

73, Stefan/DK7FC

Am 11.01.2012 13:40, schrieb Douglas D. Williams:
I'll give a listen tonight, Stefan, if you are still in QRP mode.

Doug

On 1/11/12, Stefan Schäfer<[email protected]>  wrote:
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
<http://dl.dropbox.com/u/19882028/Datenbl%C3%A4tter/irfp460.pdf>  will be
replaced by a SPW20N60C3
<http://dl.dropbox.com/u/19882028/Datenbl%C3%A4tter/SPW20N60C3.pdf>  :-)

73, Stefan/DK7FC



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