[Yaesu] Re: [Kenwood] anyone sweep a Murata K12 filter?

Sat, 6 Mar 2004 12:25:16 -0800

Hi Clark,

One can easily "sweep" any filter in their radio using the digital
frequency readout, the frequency tuning knob, the S-meter, and the
built-in crystal calibrator as a constant level signal source. 
Disconnect the external antenna to avoid outside interference potential.

To simplify the readings & record keeping, I set the receive frequency
such that the crystal calibrator signal is exactly S-9 at its strongest
point.

Knowing the filter bandwidth you expect to cover, and how many data
points you wish to take to adequately characterize the filter, you can
calculate the frequency step size (10Hz, 50Hz, 100Hz, etc.) needed.  At
each step I enter the frequency and the amplitude (assuming 5db/S-unit)
into an Excel spreadsheet.  From that data use Excel to plot a
traditional graph of Amplitude vs Frequency.

It is certainly not to National Bureau of Standards accuracy by a long
way, but it is probably good within a couple of db, which for amateur
radio purposes is usually sufficient.

I've done that at 10Hz and 50Hz intervals on my old TS-930SAT that has
the stock Kenwood 2.4KHz and 500Hz filters in both IFs.  I would be happy
to send the 10Hz interval Excel spreadsheet and graphs as an attached
file if you wish.  (The 10Hz intervals were unnecessarily narrow for the
2.4KHz wide bandwidth but just right for the 500Hz bandwidth filters.)

Tom, K6ZT

On Fri, 5 Mar 2004 21:36:53 -0800 Clark Savage Turner <[email protected]>
writes:
> Just curious if anyone has ever swept the Murata CFJ455 K12 filter.  
> It 
> is the stock filter in the Kenwood 850, 940 (some 930's and some 
> 830's).  I think it came stock in some FT 1000's (as well as the 
> K13?) 
> and perhaps others.
> 
> I wanted to compare it to the K14 filter, the stock filter in the TS 
> 440 
> and the FT-897.  It is the same size and plug compatible, the K12 
> has a 
> little more bandwidth and was said by Rich Measures (some time ago) 
> to 
> have much better skirts.  Is it true?
> 
> Clark
> WA3JPG
> 
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