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Author Topic: Some help with CW alignment IC-821H  (Read 3932 times)
KD0OCY
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Posts: 17




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« on: February 27, 2013, 03:57:40 PM »

Hi. I am trying to figure out a bit about getting the CW back on frequency with this rig. I haven't done much work on anything so I am very inexperienced so I need a little help making sense of it all. Here are the details....

I have two friends with some older Kenwood 2m all mode radios that both have me at about 2k off (low) on my CW.

I also have an MFJ 269 which reads me at 4k high. Using a bnc 2 meter HT antenna connected to the frequency counter to read this.

Going through the the Service Manual, it has been told to me that 5-3 (Frequency Adjustment) is what I might need to adjust to fix the problem.  I tried this while monitor my Frequency counter on the MFJ 269 and had a friend listening from his station to see what changes transpired. This didn't seem to change anything.  Not on receive and not on transmit.  I had marked the position it was already set to and moved it back when we were finished with it.

Not sure what to check or change to bring my CW on frequency. I've been practicing the code for a while now and am just now finding a few other hams interested in learning code to practice with. On top of that the club noticed we were interested in learning code and now we might be starting some training sessions so it would be great if I could get this on frequency!  Any help is greatly appreciated!


Forgot to give a link to the service manual....

https://docs.google.com/file/d/0BxNNq7P29eFSVFpUbFFoUVR6Wm8/edit?usp=sharing
« Last Edit: February 27, 2013, 04:06:19 PM by KD0OCY » Logged
TANAKASAN
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Posts: 933




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« Reply #1 on: February 28, 2013, 12:24:50 AM »

OK, first the good bit, "I had marked the position it was already set to and moved it back when we were finished with it". Well done, if all people tempted to align rigs would do this then the world would be a better place.

Now, RTFM (Read The Fine Manual). I'm not trying to be clever here but you're missing the important stuff and we need to put you right.

1) You will need an accurate frequency counter, Icom specify a unit that is accurate to +/- 1 part per million and an MFJ 269 probably won't cut it here. Borrow something decent or, maybe, take your rig along to a service department somewhere that has an accurate frequency counter.

2) Carry out section 5-2 PLL ADJUSTMENT. If you don't have an RF Voltmeter then a scope with a fifty ohm resistor across the input can be an acceptable substitute. Adjust L42 and L43 for maximum then connect your accurate counter and adjust X1 for 60.400000 MHz.

That's it, there are no other frequency settings to adjust inside because the IC-821H uses a PLL referenced to that 60.4 MHz oscillator to drive your first mixer and the same 60.4 MHz drives a pair of DDS chips to generate the BFO signals (bottom of page 2 section 10). Section 5-3 sets the FM Transmit frequency and won't change anything in SSB or CW.

Tanakasan





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WB6BYU
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Posts: 13580




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« Reply #2 on: February 28, 2013, 12:07:05 PM »

If you are off 2kHz, perhaps you are receiving on the wrong sideband?
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KD0OCY
Member

Posts: 17




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« Reply #3 on: February 28, 2013, 04:36:39 PM »

Thanks. Really appreciate that. I know someone with a good counter and I intend to purchase a scope soon.

Seems like using the resistor with the scope was on one of the exams somewhere. 

Again. Really appreciate it. I have a club meet tonight so ill ask around for some help with the equipment.
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