Ok Alan,
Ok , no problem on the 'isolation' using a inductor , I was thinking more
of the power supply demand/regulation side of things , looks like these
things are a bit tricky to feed 'dc' interms of peak demand on the suppy
... this slides into calcuations of actual power supplied, form factors etc
, these must affect power supply design in terms of regulation bandwith ,
parasitic inductance etc ? , that was the link to mobile phones !
G ..
----- Original Message -----
From: "Alan Melia" <[email protected]>
To: <[email protected]>
Sent: Saturday, March 08, 2008 1:40 PM
Subject: Re: LF: Re: Smaller DC feeding choke in class E amplifier
Hi Graham, well there is not a lot of difference between "pulse amps" and
any other sort really from that point of view. The choke "opposes changes
in
current" and also allows the signal to go to the load rather than be short
circuited by the PSU. At HF the situation is slightly different as you can
run into resonances as well, but as I understand most mobile phones use
Class E for efficiency and battery life in just the same way as we use 'em
on LF....that is if you ever switch em on (I hardly ever do !!) Being
digital they dont need to be linear.
Alan
----- Original Message -----
From: "Graham" <[email protected]>
To: <[email protected]>
Sent: Saturday, March 08, 2008 11:43 AM
Subject: Re: LF: Re: Smaller DC feeding choke in class E amplifier
Hi Alan,
I never could get a handle on using passive components to feed pulse
amps
,
a sort of
contradiction ? what do they do in a mobile phone ?
G ..
----- Original Message -----
From: "Alan Melia" <[email protected]>
To: <[email protected]>
Sent: Saturday, March 08, 2008 12:30 AM
Subject: Re: LF: Re: Smaller DC feeding choke in class E amplifier
> Hi Joe , Thanks for the "plug" :-))
> Yes the circulating currents get pretty large with the low impednces
when
> you try to put high power out with 12 supply. It doesnt do some caps a
lot
> of good either (think of the current density in the thin foil!). Most
> of
> my
> tests were done at 35v or higher and that is a lot easier.
> Best Wishes de Alan G3NYK
>
> ----- Original Message -----
> From: <[email protected]>
> To: <[email protected]>
> Sent: Friday, March 07, 2008 11:47 PM
> Subject: Re: LF: Re: Smaller DC feeding choke in class E amplifier
>
>
>> Alan, Johan and group,
>>
>> Since experimenting on LF I have discovered the joys of Class E,
>> many thanks to Alan. My first 100W TX used an IRF-640 as
>> suggested on Alan's web page. A dozen of them could be had for about
$10
>> in 2003. Unfortunately, they are have gone up quite a bit since then,
>> although much cheaper than a 6146! There seems to be a new
>> generation
>> of hexfet such as the IRFP260 and perhaps it might be possible to use
>> this
>> in a 12volt 100w amp. Unfortunately, many 640's came to an untimely
>> demise in my unsuccessful attempts to get 100 watts with a 12 V
>> supply.
>>
>>
>> 73
>> Joe VO1NA
>>
>
>
>
>
>
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