From: Chris Wilson <dead.fets@gmail.com>
Date: Tue, 11 Apr 2017 14:43:48 +0100
Message-ID: <994947193.20170411144348@gmail.com>
To: Andy Talbot <rsgb_lf_group@blacksheep.org>
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Subject: Re: LF: Wilkinson combiners - More
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Hello Andy,

Replies  should  just go to the list, I am not very good with GMAIL, I
had  to  set  up  an  account  to  use  the Blacksheep group as it was
spitting  out  my  old e-mail address i use for everything else, let's
see if this just goes to the list...

Thanks for the tips, understood and appreciated.

Tuesday, April 11, 2017, 1:01:41 PM, you wrote:

> If your PAs are the push pull type using a transformer, you'll have
> to keep those, and take their secondary winding to the combiner.  
> Not ideal but not a lot you can do if you use that sort of design
> rather than a bridge or half-bridge


> I don't use toroids for LF transformers - never have, never would. 
> I use SMPSU cores - you know where you are with them and are safe in
> the assumption they are exactly as advertised .   Its a long time
> since I bought any, but the last ones I used were 3C90 material
> IIRC, but there's better stuff out there now.


> I might use iron dust toroids as inductive elements for filters and
> DC chokes, but gapped ferrites work as well, and rather more precise in their calculations


> As for determining core size and number of turns Just use the
> equation V >= 4.44 .F.N.A.B (all in Si units) ,     keeping B below
> around 0.1 or even below 0.07 Tesla and you're there.   Look at
> SMPSUs to get a feel for the size of core for a given power.


> If your individual modules are designed for 50 ohm load, then  your
> secondary on the combiner needs to deliver the summed power to 50
> ohms.  I only ever saw the idea used on the Deccas with their own
> individual tanks.  You'll just have to try it and see


> Just noticed you sent this message off-list ?


> Andy


-- 
Best regards,
 Chris                            mailto:dead_fets@gmail.com