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2mtr xmit/recv issue - LocOsc Freq Issue
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paul warman
开云体育Getting VERY close now. Today we double checked the voltage on TP2002 for the VHF VCOs and as before it seemed fine for the Low VHF band (up to 139.99MHz) but clung to 7v for the high VHF band (>140MHz). So, we then checked the switching voltage actually at both ends of the tracks, so at MO2001 and Q2015, they were fine switching at the 139/140MHz boundary. HOWEVER, the MO2002 and Q2016 pair did not show a changing voltage at the 139/140MHz boundary. So we checked the other side of Q2016, pin 4 and we could see the switching voltage there, so using our great powers of deduction (yeh right!) Q2016 has to be a bad-un!!!! This is an FMC3A (or FMC3AT148), so we are checking suppliers now and will probably use Aliexpress (everyone else want an order of 3,000) sadly with a few weeks delay, but it’s a cheap solution and far better than having to source the VCO! I guess our big hope is that the VCO is working fine and that it didn’t cause the switching transistor pair to blow....fingers crossed. ? Guys, thanks again so much for all your support and my local friend Tex for explaining the mysteries of the PLL circuit. ? I’ll update you when we replace the part and try the radio. ? 73. Paul, G0odp _._,_._,_ |
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paul warman
开云体育That’s a good point Nils, no I haven’t lifted the board but I have been checking voltages at both ends of the relevant tracks. I’m going to call Yaesu today to see if they have that part number, thanks for the tip. I was checking the circuit of the FT817 and I see that used similar technology with a transistor pair switch but a different part , so they could well have that part. (no….. Ive just checked, they don’t have it!) ? We’re not opening the champagne yet, but the bottle is going in the fridge to be ready! ? Do you happen to have the default settings for the jumpers around the battery, the ones used to wideband the rig? I can see the soldering around there is messy, it hasn’t been widebanded….or possibly it was and then it was reversed…. Either way the soldering looks very dodgy! ? Paul, G0odp ? From: [email protected] <[email protected]> On Behalf Of Nils Ostman
Sent: 23 March 2021 08:07 To: [email protected] Subject: Re: [YaesuFT847] 2mtr xmit/recv issue - LocOsc Freq Issue ? Great! You are getting somewhere! BUT, have you lifted the PLL board? Check for any factory mods ie. cut traces, added components and lines. The soldering skills of the guys doing the mods isn't brilliant. |
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开云体育I would like to add that I truly enjoyed this conversation.? I have learned quite a bit about our rig. It is also reassuring that there are such knowledgeable and helpful people out there.? Thank you. ? I am cheering for you and hoping the champaign is good. ? -------------------- ? From: [email protected] <[email protected]> On Behalf Of paul warman via groups.io
Sent: Tuesday, March 23, 2021 5:29 AM To: [email protected] Cc: 'John Collins' <jcolg0kfm@...> Subject: Re: [YaesuFT847] 2mtr xmit/recv issue - LocOsc Freq Issue ? That’s a good point Nils, no I haven’t lifted the board but I have been checking voltages at both ends of the relevant tracks. I’m going to call Yaesu today to see if they have that part number, thanks for the tip. I was checking the circuit of the FT817 and I see that used similar technology with a transistor pair switch but a different part , so they could well have that part. (no….. Ive just checked, they don’t have it!) ? We’re not opening the champagne yet, but the bottle is going in the fridge to be ready! ? Do you happen to have the default settings for the jumpers around the battery, the ones used to wideband the rig? I can see the soldering around there is messy, it hasn’t been widebanded….or possibly it was and then it was reversed…. Either way the soldering looks very dodgy! ? Paul, G0odp ? From: [email protected] <[email protected]> On Behalf Of Nils Ostman ? Great! You are getting somewhere! BUT, have you lifted the PLL board? Check for any factory mods ie. cut traces, added components and lines. The soldering skills of the guys doing the mods isn't brilliant. ?
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paul warman
开云体育Thanks Lawrence, yes I totally agree, I was able to get a little way in solving the problem, BUT, I needed the help of others to really understand what was going on. Also I have to say that using the oscilloscope and spectrum analyser really helped my see the issues, I could clearly see the voltage transitions…… so good friends and good test equipment are both essential! Paul, G0odp ? From: [email protected] <[email protected]> On Behalf Of lmrudner
Sent: 23 March 2021 19:44 To: [email protected] Subject: Re: [YaesuFT847] 2mtr xmit/recv issue - LocOsc Freq Issue ? I would like to add that I truly enjoyed this conversation.? I have learned quite a bit about our rig. It is also reassuring that there are such knowledgeable and helpful people out there.? Thank you. ? I am cheering for you and hoping the champaign is good. ? -------------------- ? From: [email protected] <[email protected]> On Behalf Of paul warman via groups.io ? That’s a good point Nils, no I haven’t lifted the board but I have been checking voltages at both ends of the relevant tracks. I’m going to call Yaesu today to see if they have that part number, thanks for the tip. I was checking the circuit of the FT817 and I see that used similar technology with a transistor pair switch but a different part , so they could well have that part. (no….. Ive just checked, they don’t have it!) ? We’re not opening the champagne yet, but the bottle is going in the fridge to be ready! ? Do you happen to have the default settings for the jumpers around the battery, the ones used to wideband the rig? I can see the soldering around there is messy, it hasn’t been widebanded….or possibly it was and then it was reversed…. Either way the soldering looks very dodgy! ? Paul, G0odp ? From: [email protected] <[email protected]> On Behalf Of Nils Ostman ? Great! You are getting somewhere! BUT, have you lifted the PLL board? Check for any factory mods ie. cut traces, added components and lines. The soldering skills of the guys doing the mods isn't brilliant. ?
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Nils Ostman