Re: LF: Re: RE: 472 kHz PA running at 12 VDC

[Stefan Schäfer <Stefan.Schaefer@iup.uni-heidelberg.de>]

Hi MF,

Late at night, i made draw the schematic. Here it is: https://dl.dropbox.com/u/19882028/MF/100W%20475kHz%20PA.png  (picture of prototype https://dl.dropbox.com/u/19882028/MF/DK7FC%20472%20kHz%20PA%2015W%2B100W.JPG)

Most of the parts are not critical.

The ferrite cores are the blue EPCOS types, N30 material. Details are in the image. But you may use a FT140-77 alternatively and double the primary and secondary number of turns.

There are many alternatives, also to the FETs. Instead of the IRZF48N you may try a IRF1405. This one has a lower on-resistance but a higher input capacity. Maybe it works even better, i didn't try to many parts. Switching times are not critical. So you need to find a compromise between low on resistance and input capacity while the Drain-Source voltage should be 55V for a 12V supply.

Instead of RF litz wire (i use this one: http://www.reichelt.de/index.html?ACTION=""> ) you can also use 1mm diam. enamel. Cu wire or better 5x0.4mm or what you have. It just affects the efficiency, more or less.

The overall dimensions of this prototype are 15cm x 10cm x 3cm, so it is quite compact and since it runs from a 12V battery you can use it for /p tests. Also you can of course use more than 2 power steps by using a multi step switch and more taps.

A DDS signal generator with rectangular wave form or a sine signal coming from a HF TX may be used. The waveform doesn't matter as long as the peak input voltage exceeds 5 Vp.

73, Stefan/DK7FC

PS: Yes, it is nothing new and someone has done it before!






Am 28.06.2012 11:46, schrieb M0FMT:

Hi again Stefan

 

The Litz is too, only by the Km or 10Kg reel.......... :@((

 

Do you create your own I have 0.125 solid C/E guess that could be stranded up to make a synth?

 

73 es GL Pete M0FMT IO91UX

From: M0FMT <m0fmt@yahoo.co.uk>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
Sent: Thursday, 28 June 2012, 10:22
Subject: Re: LF: Re: RE: 472 kHz PA running at 12 VDC

Hi Stefan

http://www.ebay.co.uk/itm/IRFZ24N-Transistor-x-1-pieces-IRFZ24-/160818253496?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item257183ceb8

Just over £5 a pop!

http://www.ebay.co.uk/itm/NEW-ICL7667CPA-MAXIM-IC-DRIVER-MOSFET-DUAL-PWR-8-DIP-1-PIECE-B7-/160779362423?pt=LH_DefaultDomain_0&hash=item256f326077

Just over £6 a pop!

But what is the “Unobtainium” ferrite?   …… ;0)

Chees Pete FMT

   From: Jean-Pierre Méré <jpm.f1afj@online.fr>
To: rsgb_lf_group@blacksheep.org
Sent: Thursday, 28 June 2012, 9:42
Subject: Re: LF: Re: RE: 472 kHz PA running at 12 VDC

Hello Stephan ,
Me too
73  , Jean-Pierre F1AFJ 

Le 28/06/2012 10:36, M0FMT a écrit :

Hi Stephan

 

Me Too

73 es GL Pete M0FMT IO91UX

From: "PA1SDB, Peter" mailto:pa1sdb@amsat.org
To: rsgb_lf_group@blacksheep.org
Sent: Thursday, 28 June 2012, 9:12
Subject: LF: Re: RE: 472 kHz PA running at 12 VDC

like

 

----- Original Message -----

From: Rik Strobbe

To: rsgb_lf_group@blacksheep.org

Sent: Thursday, June 28, 2012 6:35 AM

Subject: LF: RE: 472 kHz PA running at 12 VDC

If someone is interested i may convert the circuit from my mind into a schematic as a png file.

 

Always interested ;-)

 

73, Rik  ON7YD - OR7T