Topband: BCI filter for MFJ analyzer

[Jeff Le Fouler - F6AOJ]

Glen,

a 300 KW broadcat on  864 KHz is at 10 miles north-east of my station

i designed several filters to reduce inerferences

without filter i can use my beverages
http://f6aoj.ao-journal.com/crbst_86.html

the last one is a simple deep notch  of 75 dB

look her for details
http://f6aoj.ao-journal.com/crbst_234.html

see final response down in page #4 @3


73  Jeff   F6AOJ


----- Original Message ----- 
From: "Guy Olinger K2AV" <olinger at bellsouth.net>
To: "Glen" <k4kv at mds-ham.com>
Cc: "TopBand" <topband at contesting.com>
Sent: Saturday, October 03, 2009 4:56 PM
Subject: Re: Topband: BCI filter for MFJ analyzer


>
> A BC notch filter that works on 160 has two issues, first that it has to
> notch out an interfering station, and second, that at each160 frequency to
> be measured, the residual reactance of the notch must be tuned out, one
> frequency at a time.  The MFJ design will do this, but if one is being
> bothered by more than one station, a single notch will not work.
>
> Some have used a BC rejection high pass filter.  For accuracy, the 
> readings
> must be compensated by whatever reactance and impedance transformation is
> produced by the filter.
>
> Certain newer devices, the AIM4170 is one, work in concert with a PC. A
> calibration data table is created by scanning precision devices and then 
> the
> table is used in converting the raw readings to accurate presentations of
> values.  More expensive devices contain the calculating device in the 
> unit.
>
> This allows "custom" calibrations to be created looking *through* cables 
> and
> devices to precision devices on the far side. These named and saved custom
> tables can translate raw data to what would be seen on the "far" side. 
> E.g.
> one can calibrate looking through a BC filter and compensate for the
> miscellaneous distortions closer to cutoff frequency.
>
> 73, Guy.
>
> On Sat, Oct 3, 2009 at 9:31 AM, Glen <k4kv at mds-ham.com> wrote:
>
>> Hello,
>>
>> I inquired about a filter for the MFJ to block broadcast AM interference.
>> Thanks for
>> the responses!
>>
>> I built a filter from a QEX article.  The filter worked great from 3.5Mhz
>> up.  It did not
>> work for 160M.
>>
>> Just a note for others looking at QEX articles.
>>
>> 73's
>>
>> Glen K4KV
>>
>> _______________________________________________
>> Topband mailing list
>> Topband at contesting.com
>> http://lists.contesting.com/mailman/listinfo/topband
>>
> _______________________________________________
> Topband mailing list
> Topband at contesting.com
> http://lists.contesting.com/mailman/listinfo/topband
>