frequency counter not displaying anything

[chellappan]

Dear Friends, I ve made a LCD frequency counter(MAG) with PIC 16F628A for my radio receiver.I couldn't read the frequency because there is no IF offset with 12MHz.Pls send me a modified HEX file for 12MHz IF offset.
Regards
Praveen Chellappan
praveenchellappan@gmail.com

[mvs sarma]

Praveen, please go through some posts
I remember that VU3CNS gave procedure of providing for different offsets and also gave out the .asm file

[chellappan]

Dear all,
i got the hex file for 12MHz offset from ARRARTE FERNANDEZ CLAUDIO, CX5TK.Its working perfectly.Thanks a lot dear friend.

[chellappan]

Dear all,
My frequency counter shows 2.8 KHz upper than actual frequency.trimmer adjusted to correct it ,but not covering 2.8 khz.
Pls help

[mvs sarma]

mean time what crystal did you use? is that 4.000 MHz? you are supposed to have 22p caps on either side. at the worst try changing the crystal.

you may make another crystal osc outside using say 10MHz, measure that and find difference.
i used to make a 20 turns loop of enemelled wire at 2" dia , connect to probe abd take it closer to the TV and read our 15.625 KHz
while so, you can trim the trimmer cap, of the meter for correct reading. this 15.625 is supposed to be of atomic standard.


suppose you remove the IF offset and select direct >D read mode. Then check whether your LO is measured is correct including the known offset that your Rx has.

even the chip clock can be measured with a 10pF block cap on the probe

[chellappan]

Dear Sarmaji,
Thank you very much for your valuable suggestions .I checked all the points you ve noted.Its found that my Rx IF (BFO) frequency is 11999998 KHz.I am receiving on LSB mode.The IF offset frequency is 12MHZ in the counter.Actually It should be on 11999998.I think that is the cause to show 2.8 khz difference.One of my ham friend CX5TK also mentioned about this.

[mvs sarma]

I see the difference between 12 and 11.999998 as 2Hz only and not 2.8KHz. If I remember, the BFO should be around 3KHz high for LSB and 3KHz less for USB?

[chellappan]

Yes dear Sarmaji, You are absolutely right.BFO is 3 KHZ lower than 12 MHZ. So what will be my IF off set on frequency counter?

[mvs sarma]

Generally, LO would be Fin+IF and in your case it would only be 12MHz
later there would be another switch like usb / lsb, shifting a BFOof 12MHz to suite the sideband concerned.

[ON4CLQ]

Hello radiofreaks,
How high is the level p to p on the scoop on pins 2 and 3 from the pic 16F628A? I have the same problem with the fll-counter. The oscillator(4Mhz) is very good and i have checked all the components.
The lcd voltage on pin 3 is 0,5 volt and see only blocks on my display. I have checked the voltage on my regulator 7805 and also OK. 4,88 volt. Checked the levels on my transistors and also OK. What is the problem with the FLL-counter???
No results for a good working FLL-counter.
_______________________________________________________________________________________________________________________________________________________________________________________________________
Hello,
Today, after much searching, found the bug. The program in the pic changed and everything works properly now. I'm using the 1X16 and 2X16 LCD.
Do you have problems? Mail to on4clq@telenet.be

Best reagrds from Belgium, Patrick, ON4CLQ.

[mvs sarma]

congratulations !!!