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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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6th Sep 2020, 11:40 am | #1 |
Diode
Join Date: Sep 2020
Location: Bath, NE Somerset, UK
Posts: 4
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Yaesu FRDX400 sensitivity
Hi,
Trying out an FRDX400 I bought at a rally a year ago. The sensitivity seems to be very low, but only on certain bands. On 80m for example, when I connect a dummy load and switch on the xtal calibrator, once the signal is peaked with the preselector control the signal level is S9 indicated. I was using the rx on 40 and it seemed quite deaf in comparsion to the other bands. I did the same as on 80 with the calibrator signal and even when peaked it's much weaker, barely S1 shown on the meter. I tried the alignment as mentioned on page 10 of the manual, i.e. adjusting L104 and L108 for maximum reading on 40m, but the signal doesn't ever get above S1 even at maximum. All the other bands seem OK, the receiver is quite lively, but there is a definate "deafness" on 40. Any comments or suggestions welcome Thanks, Dave |
6th Sep 2020, 5:04 pm | #2 |
Heptode
Join Date: Mar 2008
Location: Newmarket, Suffolk, UK.
Posts: 611
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Re: Yaesu FRDX400 sensitivity
The usual issue in kit that has stood idle is switch wafers (generally not specific to FRDX400)
Be aware of the switch wafer insulating material absorbing the "switch cleaner" and swelling up. Just rub the wafer using a cotton bud soaked in cleaner Could be the band conversion crystal not oscillating? With a signal generator you should be able to see where the signal is disappearing or where it jumps up 73 Fred G4BWP |
6th Sep 2020, 7:18 pm | #3 |
Diode
Join Date: Sep 2020
Location: Bath, NE Somerset, UK
Posts: 4
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Re: Yaesu FRDX400 sensitivity
Thanks for the info Fred, just did a clean with cotton buds soaked in switch cleaner round the contacts of the wafers, quick re-peaking of the two inductors and the S meter reading is now just over S9 when the preselector is peaked on the calibrator signal on 40m band
73, Dave |