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Hi the SAT button on and off a few times! ? Check Q2017 is switching as this will kill off the UHF RX and TX LO this should be working as RX is working can you confirm this, tx on a hand held or signal generator ? D2017 the anodes of the diodes are switched separately for TX and RX, confirm the LO is on cathode of D2016, then follow the LO through the circuit path to the TX LO O/P via Q2039 ? 
? OK TP 4 to TP 7, is the supply to the VCO, pulled on by a PNP transistor in Q2015 to 18. ? OK we have VHF 1 + 2 and UHF 1 + 2, and 4 VCO, I suspect two are for TX and the other two for the RX VCO as they will probably be different frequencies! Or slit frequency operation (not sure here) or when TX and RX are used simultaneously in SAT mode? ? 73 ? Andrew ?
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From: Max Donoghue [mailto:ve3tmt@...]
Sent: 22 July 2022 19:34
To: Andrew
Subject: Re: If low at O/P then trace back D2016 switching? ? Went digging into the PLL board. I'm getting 3.66V at TP2003 in TX D2019 is switching as expected, one line high for HF, one for VHF and one for UHF. All three lines tested fine.On the underside of the PLL board, I am getting 7.9V on TP2006, but not TP2007 which leads to Q2018. On UHF I'm getting 7.9V on pin 2 of Q2017 but nothing on pin 2 of Q2018 check if there is something there on RX On VHF I'm getting 7.9V on pin 2 of Q2016 but nothing on pin 2 of Q2015 check if there is something there on RX ? On Fri, Jul 22, 2022 at 1:29 PM Max Donoghue <ve3tmt@...> wrote: Correction to my earlier results, TX IF signal is present on all bands.? TX LO signal is present on all bands except 440. No output there. ? On Fri, Jul 22, 2022 at 7:55 AM Max Donoghue <ve3tmt@...> wrote: No worries I appreciate all the help. ? On Fri, Jul 22, 2022, 7:51 AM Andrew <a@...> wrote: Interesting? ok I am away from home in Torquay, I have limited access to circuits? however? we are nearly there.
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On Sat, Jul 23, 2022 at 6:03 AM Andrew Lenton < a@...> wrote:
Hi the SAT button on and off a few times!
?
Hitting the SAT button lights up all the buttons for sat operation. Do hear anything click, but not sure if I am supposed to.
? Check Q2017 is switching as this will kill off the UHF RX and TX LO this should be working as RX is working can you confirm this, tx on a hand held or signal generator
RX is working, confirmed by handheld
Measurements taken:
? D2017 the anodes of the diodes are switched separately for TX and RX, confirm the LO is on cathode of D2016, then follow the LO through the circuit path to the TX LO O/P via Q2039 ?
 ?
? OK TP 4 to TP 7, is the supply to the VCO, pulled on by a PNP transistor in Q2015 to 18. ? OK we have VHF 1 + 2 and UHF 1 + 2, and 4 VCO, I suspect two are for TX and the other two for the RX VCO as they will probably be different frequencies! Or slit frequency operation (not sure here) or when TX and RX are used simultaneously in SAT mode? ?
?
73 ? Andrew ? From: Max Donoghue [mailto:ve3tmt@...]
Sent: 22 July 2022 19:34
To: Andrew
Subject: Re: If low at O/P then trace back D2016 switching? ? Went digging into the PLL board. I'm getting 3.66V at TP2003 in TX D2019 is switching as expected, one line high for HF, one for VHF and one for UHF. All three lines tested fine.On the underside of the PLL board, I am getting 7.9V on TP2006, but not TP2007 which leads to Q2018. On UHF I'm getting 7.9V on pin 2 of Q2017 but nothing on pin 2 of Q2018 check if there is something there on RX On VHF I'm getting 7.9V on pin 2 of Q2016 but nothing on pin 2 of Q2015 check if there is something there on RX ? On Fri, Jul 22, 2022 at 1:29 PM Max Donoghue <ve3tmt@...> wrote: Correction to my earlier results, TX IF signal is present on all bands.? TX LO signal is present on all bands except 440. No output there. ? On Fri, Jul 22, 2022 at 7:55 AM Max Donoghue <ve3tmt@...> wrote: No worries I appreciate all the help. ? On Fri, Jul 22, 2022, 7:51 AM Andrew <a@...> wrote: Interesting? ok I am away from home in Torquay, I have limited access to circuits? however? we are nearly there.
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Sorry did not spot the attachments check directly on the the UHF TX VCO
Does UHF RX work, judging by your measurements, I would say no.
VHF frequency of 190 Mhz was unsepected, so the LO is high
Looks like the UHF VCO has died!
Get
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I'll button it up for now so I can get back to using it and look for a PLL board to replace. Would probably be the easiest remedy.
On Sat, Jul 23, 2022, 6:13 PM Andrew Lenton < a@...> wrote:
Sorry did not spot the attachments check directly on the the UHF TX VCO
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Does UHF RX work, judging by your measurements, I would say no.
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VHF frequency of 190 Mhz was unsepected, so the LO is high
?
Looks like the UHF VCO has died!
?
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Seems odd the voltages are good on the VF0 control voltage pin!
There is not much to go wrong on a VCO I will see if I can find one!
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Am I making the correct measurements?
On Sat, Jul 23, 2022, 6:48 PM Andrew Lenton < a@...> wrote: Seems odd the voltages are good on the VF0 control voltage pin!
There is not much to go wrong on a VCO I will see if I can find one!
Get
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I do not believe in two faults, the VCO assuming it is a VCO, might me fixed frequency and the if moves to change frequency.
Check 8 V on both VCO, tx rx, the check the o/p, tx and rx share a path, this is the likely area for a fault, however, the two UHF VCO also share a reference, and if this is missing or out of lock, an inhibit will come into play. Let me study further
73
Andrew
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Dear Max, ? Take a look below: ? The UHF path to the LO output is slightly different to VHF so from D2018 it is the same, Q2022 is unique for UHF ? Bottom line: ? there is switched power on MD2003 or MD2004 Pin 4 ?there should be and o/p on Pin 3, I cannot believe both are dead! One may be. Recheck pin 3 go on the pins ? R2042 and R2047 33R check those resistors ? In our first comms, I thought you said you hand held could pick the UHF signal when on TX, is this correct, this implies all is well apart from the TX PA chain? So a bit confused here, has a plug pulled out somewhere ? VTB is the switching to D2017 ? ? 
? 
?
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From: [email protected] [mailto:[email protected]] On Behalf Of Max Donoghue
Sent: 23 July 2022 14:55
To: Andrew Lenton
Cc: [email protected]
Subject: Re: [YaesuFT847] If low at O/P then trace back D2016 switching? ? On Sat, Jul 23, 2022 at 6:03 AM Andrew Lenton <a@...> wrote: Hi the SAT button on and off a few times!
? Hitting the SAT button lights up all the buttons for sat operation. Do hear anything click, but not sure if I am supposed to. ? Check Q2017 is switching as this will kill off the UHF RX and TX LO this should be working as RX is working can you confirm this, tx on a hand held or signal generator
RX is working, confirmed by handheld ? D2017 the anodes of the diodes are switched separately for TX and RX, confirm the LO is on cathode of D2016, then follow the LO through the circuit path to the TX LO O/P via Q2039 ?
?
? OK TP 4 to TP 7, is the supply to the VCO, pulled on by a PNP transistor in Q2015 to 18. ? OK we have VHF 1 + 2 and UHF 1 + 2, and 4 VCO, I suspect two are for TX and the other two for the RX VCO as they will probably be different frequencies! Or slit frequency operation (not sure here) or when TX and RX are used simultaneously in SAT mode? ?
73 ? Andrew ? From: Max Donoghue [mailto:ve3tmt@...]
Sent: 22 July 2022 19:34
To: Andrew
Subject: Re: If low at O/P then trace back D2016 switching? ? Went digging into the PLL board. I'm getting 3.66V at TP2003 in TX D2019 is switching as expected, one line high for HF, one for VHF and one for UHF. All three lines tested fine.On the underside of the PLL board, I am getting 7.9V on TP2006, but not TP2007 which leads to Q2018. On UHF I'm getting 7.9V on pin 2 of Q2017 but nothing on pin 2 of Q2018 check if there is something there on RX On VHF I'm getting 7.9V on pin 2 of Q2016 but nothing on pin 2 of Q2015 check if there is something there on RX ? On Fri, Jul 22, 2022 at 1:29 PM Max Donoghue <ve3tmt@...> wrote: Correction to my earlier results, TX IF signal is present on all bands.? TX LO signal is present on all bands except 440. No output there. ? On Fri, Jul 22, 2022 at 7:55 AM Max Donoghue <ve3tmt@...> wrote: No worries I appreciate all the help. ? On Fri, Jul 22, 2022, 7:51 AM Andrew <a@...> wrote: Interesting? ok I am away from home in Torquay, I have limited access to circuits? however? we are nearly there.
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GO on pin 3 or the collector of Q2014, there should be a healthy signal there on RX as it is working! And on TX the seam level but a different frequency ? 73 ? Andrew ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Max Donoghue
Sent: 24 July 2022 01:25
To: [email protected]
Subject: Re: [YaesuFT847] If low at O/P then trace back D2016 switching? ? Am I making the correct measurements? ? On Sat, Jul 23, 2022, 6:48 PM Andrew Lenton <a@...> wrote: Seems odd the voltages are good on the VF0 control voltage pin! There is not much to go wrong on a VCO I will see if I can find one!
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That does not make sense, unless the UHF is banded 410 to 439 and 440 to 470 ?
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Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of Max Donoghue
Sent: 23 July 2022 14:55
To: Andrew Lenton
Cc: [email protected]
Subject: Re: [YaesuFT847] If low at O/P then trace back D2016 switching? ? On Sat, Jul 23, 2022 at 6:03 AM Andrew Lenton <a@...> wrote: Hi the SAT button on and off a few times!
? Hitting the SAT button lights up all the buttons for sat operation. Do hear anything click, but not sure if I am supposed to. ? Check Q2017 is switching as this will kill off the UHF RX and TX LO this should be working as RX is working can you confirm this, tx on a hand held or signal generator
RX is working, confirmed by handheld ? D2017 the anodes of the diodes are switched separately for TX and RX, confirm the LO is on cathode of D2016, then follow the LO through the circuit path to the TX LO O/P via Q2039 ?
?
? OK TP 4 to TP 7, is the supply to the VCO, pulled on by a PNP transistor in Q2015 to 18. ? OK we have VHF 1 + 2 and UHF 1 + 2, and 4 VCO, I suspect two are for TX and the other two for the RX VCO as they will probably be different frequencies! Or slit frequency operation (not sure here) or when TX and RX are used simultaneously in SAT mode? ?
73 ? Andrew ? From: Max Donoghue [mailto:ve3tmt@...]
Sent: 22 July 2022 19:34
To: Andrew
Subject: Re: If low at O/P then trace back D2016 switching? ? Went digging into the PLL board. I'm getting 3.66V at TP2003 in TX D2019 is switching as expected, one line high for HF, one for VHF and one for UHF. All three lines tested fine.On the underside of the PLL board, I am getting 7.9V on TP2006, but not TP2007 which leads to Q2018. On UHF I'm getting 7.9V on pin 2 of Q2017 but nothing on pin 2 of Q2018 check if there is something there on RX On VHF I'm getting 7.9V on pin 2 of Q2016 but nothing on pin 2 of Q2015 check if there is something there on RX ? On Fri, Jul 22, 2022 at 1:29 PM Max Donoghue <ve3tmt@...> wrote: Correction to my earlier results, TX IF signal is present on all bands.? TX LO signal is present on all bands except 440. No output there. ? On Fri, Jul 22, 2022 at 7:55 AM Max Donoghue <ve3tmt@...> wrote: No worries I appreciate all the help. ? On Fri, Jul 22, 2022, 7:51 AM Andrew <a@...> wrote: Interesting? ok I am away from home in Torquay, I have limited access to circuits? however? we are nearly there.
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To close the loop on this repair, I ended up removing Q4001 on the VHF/UHF amp board, I removed the 4 connecting pins, and then under jewelers glasses, touched up the 4 pads on the module. I think there was a short on pin 3, so someone may have been in there before me. After reinstalling, I had output! A quick tune up and the radio is now putting out 50W as specified.
Thank you to everyone who helped out with the repair, I am very grateful.
Max
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Andrew Lenton
