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CS-Series IF


AA7US
 

Adam,


The CS-Series is a great platform for learning and experimenting by changing a few components at a time just to see what effect it has.


So I'm curious why 8.4672 MHz was chosen as the IF in the CS-Series transceiver?


Could another frequency in the 8-10 MHz range be safely substituted for experimental purposes?  I do realize this would require completely recalculating and rebuilding the crystal ladder filter, replacing the crystal in the IF amp, and also altering the Arduino software.


Thank you,


John

AA7US


Adam Rong
 

John,

In old days, when SSB radio is homemade, 9MHz IF is used because 5.0-5.5MHz VFO can be used for both 20 meter and 80 meter bands. However, 9MHz crystal is not generally available, so nearby frequency crystals can be chosen.

Thanks,
Adam


On Oct 21, 2017 2:10 AM, landrjoh@... [CHINA_QRP] wrote:
 

Adam,


The CS-Series is a great platform for learning and experimenting by changing a few components at a time just to see what effect it has.


So I'm curious why 8.4672 MHz was chosen as the IF in the CS-Series transceiver?


Could another frequency in the 8-10 MHz range be safely substituted for experimental purposes?  I do realize this would require completely recalculating and rebuilding the crystal ladder filter, replacing the crystal in the IF amp, and also altering the Arduino software.


Thank you,


John

AA7US


kb1gmx@...
 

Here in the USA 9MHZ crystals are common.  I've built many filter using them. 
however ladder filter like in KNQ7A and others will cave a center frequency
slightly lower than 9mhz (using rocks that test at 9mhz, my filters are more like
8.997 to 8.9985mhz center frequency.)  though for this use that should be ok.

You will have to workout the capacitor values to use for that set of crystals.


Allison/Kb1GMX