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Author Topic: MFJ Cub 9030 Alignment  (Read 2572 times)
N1CHP
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Posts: 4




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« on: November 12, 2013, 12:39:12 PM »

I have ben trying to align an MFJ Cub 9030. When I adjust the BFO, I can hear the signal and stop at the lowest sound. I have noticed that the BFO does not emit any signal after the radio is turned off then back on. I am thinking that this is causing all sorts of problems. So any thoughts on why the BFO shuts off will be appreciated. I checked the soldering and continuity to the C27 cap and all seems to be ok. I continue to get a BFO signal if I tap on the C27, so it seems to be ok so far unless there is a direct problem with it.

73,
Mike
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N1CHP
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Posts: 4




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« Reply #1 on: November 12, 2013, 12:44:28 PM »

I made a mistake. It is the MFJ 9330 Cub. Not a 9030.
Mike
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W1JKA
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Posts: 1619




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« Reply #2 on: November 12, 2013, 01:19:21 PM »

You said that you "stopped at the lowest sound" as per instructions adjust C27 up or the higher side of zero beat so signal is strong. I had similar problem with my 20m Cub but problem was a cold solder joint on my Y4 xtal which also affects the BFO circuit.
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N1CHP
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« Reply #3 on: November 12, 2013, 05:22:27 PM »

Thank you. The instructions say lowest pitch. But I like the way you put it. So I will do it the way you said. I'll also check the solder joints at see if any need to be touched up at the xtal. That will lead to look at other areas of the BFO.
73,
Mike
N1CHP
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W1JKA
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« Reply #4 on: November 13, 2013, 02:42:37 AM »

Mike, apparently our instructions differ, my Cub is about 4 years old and yes when C27 is adjusted correctly your test signal for LSB will be weak or inaudible on the lo freq.(left side) but should be strong on the hi side or to the right of zero beat, my instructions have diagram to show this. Also to get my required 600 hz peak ( C note) I used my battery operated guitar tuner to match the tone since I lack the proper testing equipment. C27 being so small this is a very touchy adjustment. I also forgot to mention transformer L4 (cold joints) this is also critical along with the xtals in the BFO circuit. Good luck.
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N1CHP
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Posts: 4




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« Reply #5 on: November 13, 2013, 03:05:17 PM »

Very good. I have checked the solder joints and after a little touch up still no change. I am beginning to think that it is a bad C27. When I do get a tone it worked when I adjust L3. So I'll look around and see what happens. I have a frequency generator on my Iphone so I plan on using that. Thanks for your help.
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