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Old 22nd Jan 2023, 10:56 am   #1
mholtham67
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Default Yaesu FRDX 400 very deaf on band 10A only

The receiver is working very well generally. CB, 10B 10C 10D
Noise can be peaked with the preselector and signals heard although these bands do require realingning. The lower bands are very lively.

The problem lies with 10A, no discernable noise peaked with preselector it is however receiving bang on frequency. As far as I can see all 10mtr bands use the same front end filters. The band switch is fine. BTW, it does receive signal correctly on this band but massively down. Any ideas??
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Old 22nd Jan 2023, 11:46 am   #2
Jon_G4MDC
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Default Re: Yaesu FRDX 400 very deaf on band 10A only

It seems likely that the 33.8535 crystal is oscillating but not giving full output?
I would use a diode probe on S102 wafer G to start with.

It seems strange that V102 anode tuning is done in band pairs for 10m so there is one trimmer for 10A and 10B TC103. Maybe that has to be balanced to suit the two frequencies and yours has drifted high?
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Old 22nd Jan 2023, 1:13 pm   #3
SiriusHardware
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Default Re: Yaesu FRDX 400 very deaf on band 10A only

From what Jon says you might also be able to check this by swapping the 10A and 10B band crystals and seeing if the 'quiet' fault moves to 10B along with the crystal.

If you have the means to look at the signals as Jon suggests without disturbing any components unnecessarily, that would be the better approach.
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Old 22nd Jan 2023, 2:02 pm   #4
G6Tanuki
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Default Re: Yaesu FRDX 400 very deaf on band 10A only

Thougfh it has a "CB" position, it's not unknown for one of the 10-Metre-band positions to also be modified for operation on the 11-Metre band so it covers the part not covered by the "CB" setting.

I would be closely checking all the coils/capacitors associated with the deaf 10-Metre setting for evidence that they may have been twiddled...
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Old 17th Mar 2023, 10:49 pm   #5
mholtham67
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Default Re: Yaesu FRDX 400 very deaf on band 10A only

Hi Guys

Thanks for your thoughts on this. I will certainly try all suggestions.
I am keen to get this up and running as apart from the above problem the radio is mint.

I do apologise for the delay in thanking you for your help. I have had some major
Eyesight problems which have stopped me in my tracks.

Regards

Mick G0EIG
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