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Ultimate 3S Keeps Blowing Finals

Todd Christell All Messages By This Member #25104 Greetings: I built the 3S about 6 months ago and when it works it works great (multiple contacts to DP0GVN with a vertical in Missouri). It will work for a week or so and then it fails. I replace the BS170 (I put in a socket) and life is good; for a week or so. I set the bias according to the video several times with no luck.? I'm only running a single BS170 and I was wondering if I might have more luck adding two more to the mix??? Thanks in advance and 73, Todd AD0RR -- "When you want to build a ship, do not begin by gathering wood, cutting boards, and distributing work, but awaken within the heart of man the desire for the vast and endless sea" --?Antoine de Saint Exupéry
Al Holt All Messages By This Member #25106 That's an interesting problem. Have you checked the U3S' current draw through the power supply in both 'idle' and 'transmit?' That might give you an idea if for some reason the PA is drawing too much current. Another factor might be the type of RF choke you're using the bifilar or the single wound toroid. Do you know how much power you are getting out of the single BS170?? I would also consider a separate power supply for the PA. I think 9V with 2 BS170's is a nice set up, but still biasing them for ~200mW output. Good luck! --Al WD4AH
Vernon Matheson #25107 开云体育 Todd are you confident you dont have a intermittent issue with your connection to your antenna and antenna itself? Vernon Sent from my Samsung Galaxy smartphone. toggle quoted message Show quoted text -------- Original message -------- From: Todd Christell <todd@...> Date: 2018-07-10 12:53 (GMT-04:00) To: [email protected] Subject: [QRPLabs] Ultimate 3S Keeps Blowing Finals Greetings: I built the 3S about 6 months ago and when it works it works great (multiple contacts to DP0GVN with a vertical in Missouri). It will work for a week or so and then it fails. I replace the BS170 (I put in a socket) and life is good; for a week or so. I set the bias according to the video several times with no luck.? I'm only running a single BS170 and I was wondering if I might have more luck adding two more to the mix??? Thanks in advance and 73, Todd AD0RR -- "When you want to build a ship, do not begin by gathering wood, cutting boards, and distributing work, but awaken within the heart of man the desire for the vast and endless sea" --?Antoine de Saint Exupéry
Todd Christell All Messages By This Member #25108 Al: I haven't checked during transmit, I'll try and do that tonight. I'm powering everything through a simple linear power supply. I might try isolating the power to the BS170s. When I checked the power out is seemed to be, like yours, about 200mW although my measurement isn't that sophisticated.?? Todd AD0RR toggle quoted message Show quoted text On Tue, Jul 10, 2018 at 12:29 PM, Al Holt <grovekid2@...> wrote: That's an interesting problem. Have you checked the U3S' current draw through the power supply in both 'idle' and 'transmit?' That might give you an idea if for some reason the PA is drawing too much current. Another factor might be the type of RF choke you're using the bifilar or the single wound toroid. Do you know how much power you are getting out of the single BS170?? I would also consider a separate power supply for the PA. I think 9V with 2 BS170's is a nice set up, but still biasing them for ~200mW output. Good luck! --Al WD4AH -- "When you want to build a ship, do not begin by gathering wood, cutting boards, and distributing work, but awaken within the heart of man the desire for the vast and endless sea" --?Antoine de Saint Exupéry
Todd Christell All Messages By This Member #25109 Hi Vernon: I'm using my vertical Hustler 6B for the radio. It's the same antenna that I switch to for my normal HF operations.? When I stop seeing reports on they are gone until I replace the FET.? Todd AD0RR toggle quoted message Show quoted text On Tue, Jul 10, 2018 at 1:40 PM, Vernon Matheson <vmath@...> wrote: Todd are you confident you dont have a intermittent issue with your connection to your antenna and antenna itself? Vernon Sent from my Samsung Galaxy smartphone. -------- Original message -------- From: Todd Christell <todd@...> Date: 2018-07-10 12:53 (GMT-04:00) To: [email protected] Subject: [QRPLabs] Ultimate 3S Keeps Blowing Finals Greetings: I built the 3S about 6 months ago and when it works it works great (multiple contacts to DP0GVN with a vertical in Missouri). It will work for a week or so and then it fails. I replace the BS170 (I put in a socket) and life is good; for a week or so. I set the bias according to the video several times with no luck.? I'm only running a single BS170 and I was wondering if I might have more luck adding two more to the mix??? Thanks in advance and 73, Todd AD0RR -- "When you want to build a ship, do not begin by gathering wood, cutting boards, and distributing work, but awaken within the heart of man the desire for the vast and endless sea" --?Antoine de Saint Exupéry -- "When you want to build a ship, do not begin by gathering wood, cutting boards, and distributing work, but awaken within the heart of man the desire for the vast and endless sea" --?Antoine de Saint Exupéry
Al Holt All Messages By This Member #25110 Another question is how warm does the BS170 get during the 2 minute WSPR cycle? I tend to worry about them getting too hot if operating with high a duty cycle. I my situation my U3S is coupled with the 5W amp and I only run 1 BS170 on the 5V supply with the 'straight wound' toroid. But since the whole lot is in a not very well ventilated case I use a homebrew heatsink on the BS170.? --Al
Todd Christell All Messages By This Member #25212 Hi Al (et al):? Had time to put my 3S on the bench and got some interesting results: Old FET (the one I thought was bad) Idle current: 68 mA Transmit current: 240 mA Output voltage 3.63 volts (on an old version of the Hendricks 50 ohm dummy load so maybe ~200 mW) New FET Idle current: 68 mA Transmit current: 230 mA Output voltage: 3.48 volts Two net FETs Idle current: 70 mA Transmit current: 323 mA Output voltage: 6 volts (~400 mA) Still no contacts Conclusion?: It appears that my FET is/was OK. It may have been coincidence that after I replaced it the first time I started logging contacts. Ran my antenna system on the analyzer and everything looks OK. The only thing I can think of now is either something wrong in my configuration or possibly a timing issue. I have the GPS unit and it is showing good satellite lock. I was also a little surprised that the 40% increase in transmit current gave me a 72% increase in output power.?? So, I will start looking at configuration and calibration.?? 73, Todd AD0RR toggle quoted message Show quoted text On Tue, Jul 10, 2018 at 2:33 PM, Al Holt <grovekid2@...> wrote: Another question is how warm does the BS170 get during the 2 minute WSPR cycle? I tend to worry about them getting too hot if operating with high a duty cycle. I my situation my U3S is coupled with the 5W amp and I only run 1 BS170 on the 5V supply with the 'straight wound' toroid. But since the whole lot is in a not very well ventilated case I use a homebrew heatsink on the BS170.? --Al -- "When you want to build a ship, do not begin by gathering wood, cutting boards, and distributing work, but awaken within the heart of man the desire for the vast and endless sea" --?Antoine de Saint Exupéry
Roger Hill All Messages By This Member #25214 开云体育 Hi Todd: Are you getting the once-per-second heartbeat ok? Roger G3YTN --- Roger Hill toggle quoted message Show quoted text On 2018-07-16 16:19, Todd Christell wrote: Hi Al (et al):? ? Had time to put my 3S on the bench and got some interesting results: ? Old FET (the one I thought was bad) Idle current: 68 mA Transmit current: 240 mA Output voltage 3.63 volts (on an old version of the Hendricks 50 ohm dummy load so maybe ~200 mW) ? New FET Idle current: 68 mA Transmit current: 230 mA Output voltage: 3.48 volts ? Two net FETs Idle current: 70 mA Transmit current: 323 mA Output voltage: 6 volts (~400 mA) Still no contacts ? Conclusion?: It appears that my FET is/was OK. It may have been coincidence that after I replaced it the first time I started logging contacts. Ran my antenna system on the analyzer and everything looks OK. The only thing I can think of now is either something wrong in my configuration or possibly a timing issue. I have the GPS unit and it is showing good satellite lock. ? I was also a little surprised that the 40% increase in transmit current gave me a 72% increase in output power.?? ? So, I will start looking at configuration and calibration.?? ? 73, ? Todd AD0RR ? On Tue, Jul 10, 2018 at 2:33 PM, Al Holt <grovekid2@...> wrote: Another question is how warm does the BS170 get during the 2 minute WSPR cycle? I tend to worry about them getting too hot if operating with high a duty cycle. I my situation my U3S is coupled with the 5W amp and I only run 1 BS170 on the 5V supply with the 'straight wound' toroid. But since the whole lot is in a not very well ventilated case I use a homebrew heatsink on the BS170.? --Al ? -- "When you want to build a ship, do not begin by gathering wood, cutting boards, and distributing work, but awaken within the heart of man the desire for the vast and endless sea" --?Antoine de Saint Exupéry ?
Todd Christell All Messages By This Member #26168 I keep forgetting to update everyone on this problem after getting such great ideas.? After I tried the proffered troubleshooting tips I decided that my problem was not actually the BS170s. It ended up being a low quality intermittent cable from the GPS to the 3S.? I had salvaged an old DE9 computer cable and it seems that when I rearranged my equipment (which happens regularly) I moved the cable enough to cause problems. I changed the BS170 and the process of putting it back in service moved cables enough to make it work again.? Anyway, I changed the cable and the 3s has been transmitting without issues for the last 4 weeks or so (except during storms :) ) Thanks for your tips, Todd AD0RR toggle quoted message Show quoted text On Tue, Jul 10, 2018 at 10:53 AM, Todd Christell <todd@...> wrote: Greetings: I built the 3S about 6 months ago and when it works it works great (multiple contacts to DP0GVN with a vertical in Missouri). It will work for a week or so and then it fails. I replace the BS170 (I put in a socket) and life is good; for a week or so. I set the bias according to the video several times with no luck.? I'm only running a single BS170 and I was wondering if I might have more luck adding two more to the mix??? Thanks in advance and 73, Todd AD0RR -- "When you want to build a ship, do not begin by gathering wood, cutting boards, and distributing work, but awaken within the heart of man the desire for the vast and endless sea" --?Antoine de Saint Exupéry -- "When you want to build a ship, do not begin by gathering wood, cutting boards, and distributing work, but awaken within the heart of man the desire for the vast and endless sea" --?Antoine de Saint Exupéry

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