Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

donate to eham
   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: pulling 7023 kh xtals  (Read 970 times)
AK0B
Member

Posts: 375




Ignore
« on: August 03, 2019, 11:00:18 AM »

I expect most have seen the china pixie.   typically under $3 each with free shipping.  The connectors with shipping cost more than that.  So not a bad way to fill up the parts box.  I was wondering if anyone had tried moving the frequency of the 7023 khz crystal?

Did you have any luck, if so how did you do it.

I am extra so can operate on 7023 and find a lot of dx around their.  But thinking about experimenting with a series inductor to play with the xtal freq. I am sure I can move it down.  but be nice to move it up 5 to 9 khz.

Truthful I bought some for the parts and feel my $2.16 each for five of them with free shipping was a bargain.

Anyone else playing with them. 

Stan AK0b


Logged
WB6BYU
Member

Posts: 18529




Ignore
« Reply #1 on: August 04, 2019, 06:00:03 PM »

It depends on the circuit, especially whether the crystal is being used in parallel or series resonant mode.
You can certainly try a capacitor in series (or across) the coil and see how far you can shift it while still
maintain stability.

You can also try putting two such crystals in parallel - that technique of increasing the pulling range
originated in Japan some years ago.

But 10 kHz is a pretty big shift for a stock crystal.  IIRC, an XY cut crystal could cover 25 kHz or so, but
you'd have to special order that, and it would be much easier to have them grind a standard crystal to
a higher frequency. 

(Of course, you could unsolder the crystal case and try to grind it yourself, but it may be difficult to
recreate the original hermetic seal on the can.)
Logged
AK0B
Member

Posts: 375




Ignore
« Reply #2 on: August 05, 2019, 05:53:59 AM »

Thanks WB6BYU,   Looks like paralleling two and using a cap is the only logically way.  The American QRP club web site has a NorCal Project paper by NB6M But it is so complex be easier to just build a VFO.

So I am just going to parallel a couple xtals.  Around 7023 khz is a good DX area. 

73 de Stan AK0B
Logged
KB1GMX
Member

Posts: 1825




Ignore
« Reply #3 on: August 05, 2019, 09:21:33 AM »

Having played with VXOs and built more than a few:

Its fairly easy to pull a crystal down.  Even with paralleled crystals
and series capacitor pulling it up rarely goes more than 3-4 khz
and at 7mhz likely less.

If you want to get to 7030 a good place to start is with a
7030 crystal or even 7032.  Why? because you can go down
but going up is more limited.

The alternate is a 14060khz, 21090khz, or 28120khz and then
divide by 2,3, or 4.

Or considering the price of most custom crystals a DDS
(or si5351) and microprocessor becomes very attractive
and far more flexible.

Allison
Logged
VK3YE
Member

Posts: 267


WWW

Ignore
« Reply #4 on: August 06, 2019, 02:04:32 AM »

This video might be helpful in pulling crystals up https://www.youtube.com/watch?v=7QlDHVJ_B8g

You have to keep capacitances low.

As said before you can go down further. Maybe even 15 or even 20 kHz down (at 7 MHz).
Logged

Peter VK3YE

One ham radio post each day. Visit http://dailyantenna.blogspot.com
Author of top selling $US 5 amateur radio ebooks on antennas, QRP, getting started and more. See http://home.alphalink.com.au/~parkerp/vk3yebooks.htm
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!