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To TX on SSB any Frequency FM works fine

Andrew Lenton All Messages By This Member #386 Edited My basic problem is I seem to have lost Mic audio after Q1053 there is nothing coming out of Pin 4. Pin 4 travels half way around the radio and ends up at Q1038 Pin 6. Q1053 is an electronic attenuator controlled by Pin 3, this does move up and down with the mic gain control. ? If I switch the monitor on I hear my Mic audio coming out the speaker, so this obviously takes another path. Not sure where. There are no voltages or waveforms on the technical supplement, so I have no of knowing what is normal. ? ? The output of IC Q1063 ends up on Pin 12 on IC 1C1081 (switch) ?which in accessible on the top side of the AF board. The Voltage levels on Q1053 would also be useful, if you can get there and measure them. ? Is there any way anyone could scope a working model and let me know if audio is getting through and roughly the levels? This way I know roughly where my fault lies? 73 Andrew G8UUG ? image_2022-03-05_140227.png FT 847 AF1 Board.png
Andrew Lenton All Messages By This Member #387 Adding circuit tat was cut off I have also added some voltage for Q1063: Pin 1, Pin 3.8V 2, 1.8 Volt, Pin 3, 3.6-4.8V (mic gain control range) Pin4 3.7V Pin 5 earth, Pin6 NC, Pin7 3.7V, Pin 8 4.2V Pin 9 3.6V Pin 10 7.4V? Pin 2 seems low which is the audio out on the current mirror circuit, but nothing is coming out! 73 Andrew image_2022-03-05_174259.png
Nils Ostman All Messages By This Member #388 Hi, I did a brief check on a working 847: Q 1053 Pin 1? ?3.8 Pin 2? ?1.9 Pin 3? ?3 - 5 depending on mic gain Pin 4? ?3.9 Pin 5? ?gnd Pin 6? ?nc Pin 7? 3.8 Pin 8? ?4.2 Pin 9? 3.7 Pin 10 7.6 Measured? with a Fluke. The LF level on pin2 (out) and pin4 (in) are about the same with the mic gain i middle position. /Nils SM7DVO
Andrew Lenton All Messages By This Member #389 开云体育 Hi Nils, ? Thank you very much this compares to my readings, it is odd not to see the AF output on pin2, but it is there further up the food chain on the input to the balanced modulator ? 73 ? Andrew ? toggle quoted message Show quoted text From: [email protected] [mailto:[email protected]] On Behalf Of Nils Ostman Sent: 06 March 2022 13:54 To: [email protected] Subject: Re: [YaesuFT847] To TX on SSB any Frequency FM works fine ? Hi, I did a brief check on a working 847: Q 1053 Pin 1? ?3.8 Pin 2? ?1.9 Pin 3? ?3 - 5 depending on mic gain Pin 4? ?3.9 Pin 5? ?gnd Pin 6? ?nc Pin 7? 3.8 Pin 8? ?4.2 Pin 9? 3.7 Pin 10 7.6 Measured? with a Fluke. The LF level on pin2 (out) and pin4 (in) are about the same with the mic gain i middle position. /Nils SM7DVO
Nils Ostman All Messages By This Member #390 Hi Andrew, Have you checked the reverse side of the AF-board? i ,had an "impossible" problem with full power on FM/SSB but only 100 mW in CW. There was a sloppy "factory mod" under Q1081. /Nils?
Andrew Lenton All Messages By This Member #391 开云体育 Yes thanks for that I have found the fault it was the 2^nd TX I.F. Mixer out of lock! And there are all sorts of little mods everywhere and not on the circuit diagram ? 73 ? Andrew ? toggle quoted message Show quoted text From: [email protected] [mailto:[email protected]] On Behalf Of Nils Ostman Sent: 07 March 2022 07:19 To: [email protected] Subject: Re: [YaesuFT847] To TX on SSB any Frequency FM works fine ? Hi Andrew, Have you checked the reverse side of the AF-board? i ,had an "impossible" problem with full power on FM/SSB but only 100 mW in CW. There was a sloppy "factory mod" under Q1081. /Nils?

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