[ARC5] Fw: ARC-5 Crystal Question

[Henry Mei'l's]

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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