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Author Topic: mfj-9440 travel transceiver  (Read 1216 times)
KG6BRG
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Posts: 119




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« on: February 25, 2013, 08:35:32 AM »


Anyone know if there is a way or procedure to calibrate the receive signal on the "S" meter. Not a sensitivity issue, just an "S" meter that reads very high, in fact it pins the needle on just moderate signals. Thanks for reading.
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KB4QAA
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« Reply #1 on: February 25, 2013, 08:57:07 AM »

Sure, you use a signal generator to inject a signal into the antenna port.  Then you measure the voltage level, and adjust the metering circuit.   You need to decide what signal level you want to be represented on the meter.  Each manufacturer decides what level they use.  One level that has often been used in the industry is 50mv = S9.
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KG6BRG
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« Reply #2 on: February 25, 2013, 09:05:26 AM »

Thanks for the response, I am aware of the method you describe but I don't see anywhere to adjust the meter circuit.  That's my question.  I've done an alignment as per the manual and still have the same issue.  I've called mfj and they said to replace the meter, and they sent one to me free of charge.  I didn't think it would help, but I did replace it and I don't see any change.   Thanks for your time.
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WB2WIK
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« Reply #3 on: February 25, 2013, 11:53:22 AM »

They don't provide a schematic on line; is there a schematic in the manual they ship (hard copy)?
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AA4PB
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« Reply #4 on: February 25, 2013, 12:18:38 PM »

There's a component position drawing in the on-line manual along with instructions on how to set the AGC pot and the S-Meter zero pot on the PC board. One or both of those setting being off could cause the S-meter to read high.

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KG6BRG
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« Reply #5 on: February 25, 2013, 12:23:42 PM »

There's a component position drawing in the on-line manual along with instructions on how to set the AGC pot and the S-Meter zero pot on the PC board. One or both of those setting being off could cause the S-meter to read high.



Thanks, I've done that, still have the issue.  I will get my schematic this week, it's not here.  I have a hard time reading the schematics in PDF format.  thanks again for the comments so far.  cheers.
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KA5IWO
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Posts: 131




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« Reply #6 on: March 22, 2013, 11:10:04 AM »

Did you ever get your schematic for this radio??
I have one here for it, they are simple to repair.
I have 2 of the 9440 rigs, they are great.

Kevin
KA5IWO
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