Hi Paul,
Mix #2 (µi=10) is certainly the right choice for a LPF
as Stefan and Tobias have pointed out.
I use it too for my MW PA.
The manufacturer on
http://www.id-elektronik.de/en/index.htm => click on MW-Components
uses for his LPFs #6 (yellow) Mix iron powder which has an even lower
permeability,
i.e. µi=8.
73
Clemens
DL4RAJ
>-----Original Message-----
>From: [email protected]
>[mailto:[email protected]] On Behalf Of Paul Nicholson
>Sent: Saturday, March 12, 2016 8:48 AM
>To: [email protected]
>Subject: Re: LF: EbNaut from Todmorden
>
>Thanks Tobias and Stefan!
>
>I ordered a few T130-2 and a couple of T200-2, should arrive
>in time for next weekend.
>
>Meanwhile, I rebuilt the filter using air cored coils and
>it works great. A lovely 200W sine wave into the dummy load
>and nothing gets hot! After a while the output transformer
>is just slightly warm. DC in was 240W from a 60V supply and
>it seems I don't need a cooling fan anywhere.
>
>I turned the supply down to 10V and put a few volts of RF onto
>the antenna (untuned) and got a bright line on Gary Taylor's
>grabber - I was expecting a faint line!
>
>A better RF ground is needed, there's some RF current going
>to earth via the domestic ground which I'm not keen on.
>So I'll put another transformer at the far end of the coax and
>match the antenna/ground to its secondary. I've run out of
>toroid cores so it'll be lots of wire wound round a bucket.
>
>That's the plan for today anyway, while the weather is good.
>Maybe some transmission tonight if there's no VLF activity.
>
>--
>Paul Nicholson
>--
>
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