[ARC5] Fw: ARC-5 Crystal Question

Mon Aug 16 02:12:16 EDT 2010

You could use an adjustable cap as long as it was small enough to not have
significant stray cap.  I would prefer a small fixed cap.

Dennis AE6C

On Sun, Aug 15, 2010 at 10:25 PM, Henry Mei'l's <meils at get2net.dk> wrote:

> John and Dennis,
>
> Why not use an adjustable capacitor for coupling cap.C for minimum but
> usable coupling?.
>
> Henry, Cph.
>
> ----- Original Message -----
> From: "J. Forster" <jfor at quik.com>
> To: "Dennis Monticelli" <dennis.monticelli at gmail.com>
> Cc: "Discussion of AN/ARC-5 military radio equipment."
> <arc5 at mailman.qth.net>
> Sent: Monday, August 16, 2010 6:14 AM
> Subject: Re: [ARC5] Fw: ARC-5 Crystal Question
>
>
>  >I found out today, VNAs and crystal coupling are discussed in several
> > issues of QEX.
> >
> > Does anybody have web access to them?
> >
> > -John
> >
> > ===================
> >
> >
> >> John,
> >>
> >> The less capacitance the better, limited only by the sensitivity of the
> >> instrument.  I have not tried an actual characterization with a network
> >> analyzer.  Certainly seems plausible.  I wonder if there are any tips
> out
> >> there on the best way to do it.  Perhaps an Agilent app note?
> >>
> >> Dennis AE6C
> >>
> >> On Sat, Aug 14, 2010 at 1:02 PM, J. Forster <jfor at quik.com> wrote:
> >>
> >>> This is what I was suggesting:
> >>>
> >>>    ---------------o
> >>> VNA ------------------||--=-|
> >>>    ---------------o       ===
> >>>                   |       === Crystal
> >>>                   |--------|
> >>>
> >>> I've not thought about the coupling C size. It might need to be smaller
> >>> then 32 pF.
> >>>
> >>> -John
> >>>
> >>> ==============
> >>>
> >>>
> >>> > John,  I understand better now what you were proposing.  The other
> >>> fellow
> >>> > was proposing working with the blank and you were proposing going
> >>> through
> >>> > the holder.
> >>> >
> >>> > Dennis AE6C
> >>> >
> >>> > On Sat, Aug 14, 2010 at 6:37 AM, J. Forster <jfor at quik.com> wrote:
> >>> >
> >>> >> OK. I was just planning to take a coax from the VNA to a small
> series
> >>> >> cap
> >>> >> (about 32 pF) and the other side of the C to GND via the crystal.
> >>> >>
> >>> >> -John
> >>> >>
> >>> >> ============
> >>> >>
> >>> >>
> >>> >> > Let us know how effectively you can excite a blank using these
> >>> >> proposed
> >>> >> > methods.  There needs to be a fair amount of coupling to the Z
> axis
> >>> of
> >>> >> the
> >>> >> > AT cut.  The FT-243 and CR-1 holders applied voltage across a
> >>> narrow
> >>> >> air
> >>> >> > gap
> >>> >> > (capacitance) to both sides of the blank while holding everything
> >>> in
> >>> >> > position with corner pressure points (where there is the least
> >>> >> dampening
> >>> >> > of
> >>> >> > vibration).
> >>> >> >
> >>> >> > Dennis  AE6C
> >>> >> >
> >>> >> > On Fri, Aug 13, 2010 at 7:22 PM, J. Forster <jfor at quik.com>
> wrote:
> >>> >> >
> >>> >> >> Interesting idea, I was actually thinking of hooking the crystal
> >>> to a
> >>> >> >> modern Vector Netrwork Analyzer with a small cap.
> >>> >> >>
> >>> >> >> Best,
> >>> >> >>
> >>> >> >> -John
> >>> >> >>
> >>> >> >> ==============
> >>> >> >>
> >>> >> >>
> >>> >> >> >
> >>> >> >> > On Aug 13, 2010, at 10:55 AM, Henry Mei'l's wrote:
> >>> >> >> >
> >>> >> >> >> Will just mention that I also have used several GDOs
> >>> >> >> >> (Millen, Eico, HB ...) to check xtals- you just bring leads
> >>> from
> >>> >> the
> >>> >> >> >> xtal
> >>> >> >> >> pins into the GDO's coil socket -
> >>> >> >> >
> >>> >> >> > AND, if you have only the crystal blank - the raw quartz plate
> -
> >>> >> you
> >>> >> >> > balance the plate on top of the dipper coil, or lean it agains
> >>> the
> >>> >> >> > side of the coil and tune away. You are likely to get a nice
> dip
> >>> at
> >>> >> >> > the resonant frequency of the plate.
> >>> >> >> >
> >>> >> >> > Roy
> >>> >> >> >
> >>> >> >> > Roy Morgan
> >>> >> >> > k1lky at earthlink.net
> >>> >> >> > K1LKY Since 1958 - Keep 'em Glowing!
> >>> >> >> >
> >>> >> >> >
> >>> >> >> >
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