[Elecraft] K3 Low Pass Question

[David Cutter]

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.
>
>
>