Crystal off Frequency

[tighthide]

Hello
Aligning my Galaxy 2547 and found the X1 Crystal off by 4Khz manual says 20hz??
Having problems finding replacements
any sugestions?

Thanks
Plumber-G

I have the same problem and replaced VC1 but no luck. Can only get up to 10.2351 on pin 8 of IC3. I have a new X1 ordered and hope that is the problem.

 

[nomadradio]

Best way to tell how much this crystal affects your operating frequency is to compare the last digits of the AM carrier on the counter at channel 1 and then at channel 40.

This crystal only determines the 10 kHz spacing between channels. Has very little effect on the exact channel frequency.

If, for example the AM carrier is 100 Hz different (last digit of a 6-digit counter) at channel 1 than channel 40, this is what improving the 10.240 crystal will change.

And if those last digits are no more than 1/10 kHz different from channel 1 to channel 40, trimming this crystal will improve nothing.

With any luck the new crystal will be closer.

73

 

[Handy Andy]

I have the same problem and replaced VC1 but no luck. Can only get up to 10.2351 on pin 8 of IC3. I have a new X1 ordered and hope that is the problem.

Perhaps too, this might help.

The main 10.240 Xtal - if it's really off, you would have a noisy hissy receiver because of the 10.240 conversion of the IF strip - the Xtal would place its' signal into either the pass band of the image you want, or skew the image you want from the 10.7MHz image you have - that change is enough to hear when you're having frequency results like this.

The main offset IF from the RF amp to make the 10.7MHz 1st IF - that mixed frequency would get thru the 10.7 - but the error in the next mixing stage - it would be very evident.

Just to help, the 2547 may have a mod or two from the Factory this way...I call it a Mod for some changes were soldered under the board versus the cluttering of parts on the power Pin 9 - mostly due to the newer size of cap C91 pushed these parts to the bottom foil side.

Locate the PLL chip - follow this as you can to see if there is any errors or soldering problems...



The above is for the 10Z but this can also affect any 11 board - what the problem is, is with Pin 8 and Pin 9 C90 and a Jumper - along with adjacent parts that filter power to Pin 9 and this can affect any subsequent loading PAST L48.

Due to the orientation ad proximity to the clock signal - a poor soldering job or a shifted filter cap from Pin 9 can also affect the OUTPUT loading of Pin 8 which does accept input from Pin 7 AMBER - so if Pin 8 GREEN is loaded down with any issues from Pin 9 LT BLUE - it will affect how the 10.240 clock is "captured" for Pin 8 is a buffer output of the timing info received thru Pin 7 - either change C91 to a part size to fit the outline, or simple cleanup of details and flux being left behind on the foil side of the board has been the Remedy I've had to do.

 

[dxing.bruce]

Robb
Can't find crystal at RF Parts, also tried oscillators should I try a different search term??
Plumber-G

Try.
JAN CRYSTALS in Florida.

 

[nomadradio]

I think the last time I bought 10.24 crystals was from Mouser?

Or maybe Digi-Key.

73