[Elecraft] K3 Low Pass Question

[Tom W8JI]

This topic greatly interests me, because I have never found saturation or 
non-linearity in typical cores an issue.

This might be an opportunity to explore something new that I have never 
seen.


----- Original Message ----- 
From: "David Cutter" <d.cutter at ntlworld.com>
To: "Geoffrey Mackenzie-Kennedy" <gm4esd at btinternet.com>
Cc: "Elecraft Discussion List" <elecraft at mailman.qth.net>
Sent: Friday, June 18, 2010 9:47 AM
Subject: Re: [Elecraft] K3 Low Pass Question


> Hi Geoff
>
> I didn't know that about small cores, but, if I were to take on this idea, 
> I
> would use the biggest I could get in there, which is around 45mm.
>
> There's a local radio station on medium wave which has given me grief in 
> the
> past, (pre K3 mind you) and I could change it into a high pass filter just
> for that.
>
> Come to think of it, I wonder if I could make such a filter for use with 
> the
> MFJ259; that might be a better idea.
>
> David
> G3UNA
>
>
>
>> David,
>>
>> A Low Pass filter cutting off above 6m is useful here, because our not so
>> local FM BC station operates just above 100 MHz.
>>
>> I suggest that if you do convert a LPF, do not use small toroidal
>> inductors (unless "air wound") if the filter is to be used between a
>> receiver and an antenna feeder. Small cores can create IMD problems ftom
>> BC stations etc, which is one reason why the solenoid type of inductor is
>> used.
>>
>> 73,
>>
>> Geoff
>> GM4ESD
>>
>>
>> David Cutter wrote on Friday, June 18, 2010 9:27 AM:
>>
>>> I was idly wondering if I should convert them to something useful,
>>> perhaps
>>> to a band pass filter.  There's room to fit small toroid inductors
>>> instead
>>> of the solenoid types.  Then again, with the Elecraft line up I probably
>>> wouldn't benefit much, but it would be an interesting project.
>>
>>
>>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html