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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment. |
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22nd Jan 2023, 10:56 am | #1 |
Diode
Join Date: Jan 2023
Location: Plymouth, Devonshire, UK.
Posts: 9
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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?? |
22nd Jan 2023, 11:46 am | #2 |
Nonode
Join Date: Nov 2015
Location: Welwyn Garden City, Hertfordshire, UK.
Posts: 2,015
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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? Last edited by Jon_G4MDC; 22nd Jan 2023 at 12:08 pm. Reason: improved attachment |
22nd Jan 2023, 1:13 pm | #3 |
Dekatron
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,553
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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. |
22nd Jan 2023, 2:02 pm | #4 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,996
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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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17th Mar 2023, 10:49 pm | #5 |
Diode
Join Date: Jan 2023
Location: Plymouth, Devonshire, UK.
Posts: 9
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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 |