[Milsurplus] Fw: Re: BC-221 temperature compensating capacitor question -

[Jim Whartenby]

--- On Thu, 1/22/09, Jim Whartenby <antqradio at sbcglobal.net> wrote:

> From: Jim Whartenby <antqradio at sbcglobal.net>
> Subject: Re: [Milsurplus] BC-221 temperature compensating capacitor question -
> To: "John Hutchins" <olegerityincj at austin.rr.com>
> Date: Thursday, January 22, 2009, 8:21 PM
> John
> You are within +-0.0055% of your measurement standard. 
> Stated worse case accuracy for the '221 is +-0.034% at
> -30 degC and half of that on average in normal operation.
> I don't see a problem here.
> Jim
> 
> 
> --- On Thu, 1/22/09, John Hutchins
> <olegerityincj at austin.rr.com> wrote:
> 
> > From: John Hutchins
> <olegerityincj at austin.rr.com>
> > Subject: [Milsurplus] BC-221 temperature compensating
> capacitor question -
> > To: "milsurplus"
> <milsurplus at mailman.qth.net>
> > Date: Thursday, January 22, 2009, 7:07 PM
> > Oh grand wizards -
> > temperature compensating capacitor question
> > The BC-221-AK 1000Khz reference Oscillator has been
> > observed starting 
> > about 220 HZ high, 4000.220KHz on cold start 4000.220
> KHz
> > then after 
> > about 2 hours of warm-up drifts down to about 20 Hz
> below
> > 4000 KHZ at 
> > measured 3999.080 KHZ end of high band.  This found by
> > finding the zero 
> > beat taking a frequency reading on the Freq counter
> then
> > doing the same 
> > process periodically over a 2 hour period.  240Hz
> swing so
> > far.
> > 
> > The temperature compensating coils are clean and can
> move
> > freely, so 
> > that is not the problem.
> > 
> > Is this the norm expected considering the period in
> which
> > the unit is made?
> > 
> > If not what considerations and procedures would  I use
> to
> > re-compensate 
> > for the temperature environment.
> > 
> > Thanks
> > Hutch
> > 
> > 
> >
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