[ICOM] IC736_OFF_FREQ

[Rick Robinson]

Check these out and see if one of these might be your problem. There 
used to be a fix with adding a resistor to a chip and I'll look through 
my stuff and see if I can find it. This and these I've sent to you came 
straight from Icom. Another thing to consider is that your filter may 
have aged and even though you set it to factory specs it will still be 
off due to xtal aging. To remedy this adjust your lsb bfo to a known 
source that is accurate. I did this recently to a 735 and used another 
rig with headphones on and listened to myself till it sounded right. I 
then checked it with my local group, two of which have IFR's and 
rubidium standards and are know to have their radios dead on . Use a 
dummy load on the 736 to limit overload on the second receiver. Good 
luck, Rick., W8ZT










    
Knowledge Base Article 5C1C361327

Issue
My IC-736 or IC-738 HF base radio is about 800 Hz - 900 Hz off frequency.

Resolution
Reset the CPU (Hold [CLR] & [ENT] buttons and turn the radio on).

Category
Amateur : HF : 736 / 738







    
Knowledge Base Article 5B1A315118

Issue
There is a frequency jump in LSB mode after changing modes with my 736/738.

Resolution
The LSB BFO is not being switched properly by logic; unit may need a 
factory update.

To fix:
With the radio turned off, measure the resistance of pin 17 to ground on 
IC24 chip on main unit. It should be 47 K. If it measures above one 
mega-ohm, install a 47 K, 1/8 W resistor over the top of IC24 between 
pins 10 and 17.

Category
Amateur : HF : 736 / 738
   


George wrote:
> I have had this IC-736 for 7 years and it has been back to Icom twice some years back for off frequency operation. They said it is within specs! Try to tell the guys in my round table.
> Anyway I have been through this rig numerous times trying to find the problem. I have even replaced all the components in the master osc and USB-LSB oscillators with no help. I have even added the temperature compensated oscillator, still no help.
> It seems to be off 500 or so cycles.
> I performed the frequency calibration as per the instruction manual and memorizing the change, again, per the manual. No help as it's back to the 500 cycles off frequency on LSB after a few hours of non use, turned off.
> I've replaced the backup battery, still no help. Don't know about USB as I don't use that mode often.
> I have done all the field mods, no help.
> Any suggestions????
> Thanks.
> George 
> ----
> Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
> Icom Users Net: Sundays, 1700Z, 14.316 MHz
> Icom FAQ: http://www.qsl.net/icom/
>
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