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

Sun, 7 Mar 2004 00:57:30 -0000

Tom & Clark...

Its easier than that....

Download a copy of "Spectrogram". Install it in your computer.
Feed the output of the radio/filter to the Sound card input.
Feed the radio/filter with white noise or just tune to a noisy frequency.
Spectrogram will provide you with real time bandwidth envelope.

Also an excellent tool to determine Microphone or AF amplifier response.

You can switch the radio to different filters and immediately see the
passband envelope.
Remember if you do this thru a radio the IF/AF response of the radio must be
considered.

  <>--------------<>
  < 73's Jim W5IFP >
  <>--------------<>

> -----Original Message-----
> From: [email protected] [mailto:[email protected]]On
> Behalf Of T and V Rothwell
> Sent: Saturday, March 06, 2004 8:25 PM
> To: [email protected]
> Cc: [email protected]; [email protected]
> Subject: [Yaesu] Re: [Kenwood] anyone sweep a Murata K12 filter?
>
>
> 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
>