My "Vanity S/N"
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Several of you appear to be "curious" about the "vanity S/N"
of my K3. Here's "the story" ... The S/N of my K2 is 5665. I knew from watching the postings about K3 deliveries that S/N #56 was due out the door "soon". I called Aptos and asked that they bill the balance due on my K3 order to my CC and wait until S/N 56 was going out the door and stick my shipping label on that box. Nothin' special ... I was willing to wait until the "right" S/N came down the line. Hmmm ... shall I place an order for K3 #5665 "now"? Bet it won't be a very long wait. Perhaps I've already missed out .... (:-)) 73! Ken Kopp - K0PP K2 #5665 K3 #56 [hidden email] or [hidden email] _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Hi to all,
This is not a critical issue, but it might interest some. It's also not necessarily specific to K3's. Keywords might be "switching power supply", "inverter", and "grounding". The problem I describe below was never experienced with the K2, only with the K3. I exchanged the two radios to confirm this experimentally. The power supply scenario is as follows. Qty 2 - 50W Siemens solar panels on the roof above the shack supply a 12V 100A-Hr SLA battery. The battery is charged through a Micro-X charge controller, and this arrangement has been used for a few years with my K2. It seems to work well under all conditions. The K2 is the low power QRP version, and generally draws less than 2.5 A from the battery at power levels I run. The battery is connected to a Xantrex RS-400 sine wave inverter. THD on the 60 Hz output is supposed to be < 3%. Looking at its output via a Tek 2465A scope shows a very clean sine wave, even under the max 400W load. The inverter is rated 400W, with surge to 800W. The inverter feeds an Astron SL-11A switching power supply that powers the K3/10. Its output is 13.6V, and under max load at the K3 we're talking about 2.8A, or 39W. All units described above are bond-grounded to each other using a 1/2" braided strap. The strap drops 10 feet or so to an 8 foot ground rod. The ground rod is also bonded to the house ground nearby. The house ground is used for all main and backup loads for a much larger Solar PV system that we use to power the house here. When using the Battery => Inverter => SL-11A power supply => K3 power supply path to power the radio, the switching supply hums quite a lot in weird non-periodic ways. I can sometimes hear the same hum on the K3 RX audio, but have had no reports of it showing up on TX audio when I asked the other party. "Very clean audio", they would always say. Given the long-winded narrative above, does anyone have an idea about the rx noise I'm hearing? Seems like it's not getting in through the DC, since it doesn't show on SSB TX. So maybe I'm hearing it over the air? I thought this might be common mode noise, but the TX reports I've got with this power supply setup won't support that. Grounding can affect that, but since low impedance paths are connecting all the inline stuff, this doesn't seem the easy answer either. Sorry to take up so much bandwidth, but it's possible another Elecrafter type might face a similar issue. So it seemed worth the bits. BTW, connecting the K3 directly to the 12V SLA battery has none of the above effects and works fine. Please - no flames over the easy answer, OK? :) 73 and thanks for any thoughts, matt zilmer, WA6EGJ K2 s/n 2810 K3 s/n 0024 _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: K3 - Power supply question
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Guess you stumped everybody -- no responses in the list! :-)
I'm not an expert in switchers, but it seems to me that the problem might be a combination of the imperfect sine wave output from your inverter coupled with the fact that you're putting a very low load on the switcher in receive mode. (Assuming the switcher doesn't produce this hum when plugged into the mains.) I think I would try an analog supply in place of the switcher and see if you still get it. I think you wouldn't. Second, I wouldn't necessarily trust on-air reports about your transmitted audio where the signal strengths aren't extremely strong. You might have a hum on there that is quite a few dB down from peak audio, and it isn't detectable under the ambient received noise. If a local guy who is copying you S9+20 says you have no hum, then I'd believe it (if you trust his integrity and technical competence to make such a judgment). Or it could be some kind of ground loop problem, but it sounds like you have that covered. Ground current analysis in a complex home electrical/radio system is still black magic to me. :-) Bill W5WVO Matt Zilmer wrote: > Hi to all, > > This is not a critical issue, but it might interest some. It's also > not necessarily specific to K3's. Keywords might be "switching power > supply", "inverter", and "grounding". > > The problem I describe below was never experienced with the K2, only > with the K3. I exchanged the two radios to confirm this > experimentally. > > The power supply scenario is as follows. > > Qty 2 - 50W Siemens solar panels on the roof above the shack supply a > 12V 100A-Hr SLA battery. The battery is charged through a Micro-X > charge controller, and this arrangement has been used for a few years > with my K2. It seems to work well under all conditions. The K2 is > the low power QRP version, and generally draws less than 2.5 A from > the battery at power levels I run. > > The battery is connected to a Xantrex RS-400 sine wave inverter. THD > on the 60 Hz output is supposed to be < 3%. Looking at its output via > a Tek 2465A scope shows a very clean sine wave, even under the max > 400W load. The inverter is rated 400W, with surge to 800W. > > The inverter feeds an Astron SL-11A switching power supply that powers > the K3/10. Its output is 13.6V, and under max load at the K3 we're > talking about 2.8A, or 39W. > > All units described above are bond-grounded to each other using a 1/2" > braided strap. The strap drops 10 feet or so to an 8 foot ground rod. > The ground rod is also bonded to the house ground nearby. The house > ground is used for all main and backup loads for a much larger Solar > PV system that we use to power the house here. > > When using the Battery => Inverter => SL-11A power supply => K3 power > supply path to power the radio, the switching supply hums quite a lot > in weird non-periodic ways. I can sometimes hear the same hum on the > K3 RX audio, but have had no reports of it showing up on TX audio when > I asked the other party. "Very clean audio", they would always say. > > Given the long-winded narrative above, does anyone have an idea about > the rx noise I'm hearing? Seems like it's not getting in through the > DC, since it doesn't show on SSB TX. So maybe I'm hearing it over the > air? > > I thought this might be common mode noise, but the TX reports I've got > with this power supply setup won't support that. Grounding can affect > that, but since low impedance paths are connecting all the inline > stuff, this doesn't seem the easy answer either. > > Sorry to take up so much bandwidth, but it's possible another > Elecrafter type might face a similar issue. So it seemed worth the > bits. > > BTW, connecting the K3 directly to the 12V SLA battery has none of the > above effects and works fine. Please - no flames over the easy > answer, OK? :) > > 73 and thanks for any thoughts, > > matt zilmer, WA6EGJ > K2 s/n 2810 > K3 s/n 0024 > > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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My gut feel is that you may have some interaction between the
regulator/feedback loops in the inverter and switcher ... or the regulator in the switcher is affected by the filtering of the inverter. I have seen cases where perfectly well behaved power supplies (when operated alone, as their designers usually intend) can start acting strangely when one power supply feeds into another. The basic problem is feedback loop instability due to one supply regulator being affected by a non-linear "active" load presented to it by its load, which is another power supply. Just a thought. If this is the problem then a scope connected to the input of the K3 might show some ripple due to the instability but not necessarily so. Instability of this kind may not introduce much voltage ripple at all at low impedance points. Don K7FJ > Matt Zilmer wrote: >> Hi to all, >> >> This is not a critical issue, but it might interest some. It's also >> not necessarily specific to K3's. Keywords might be "switching power >> supply", "inverter", and "grounding". >> >> The problem I describe below was never experienced with the K2, only >> with the K3. I exchanged the two radios to confirm this >> experimentally. >> >> The power supply scenario is as follows. >> >> Qty 2 - 50W Siemens solar panels on the roof above the shack supply a >> 12V 100A-Hr SLA battery. The battery is charged through a Micro-X >> charge controller, and this arrangement has been used for a few years >> with my K2. It seems to work well under all conditions. The K2 is >> the low power QRP version, and generally draws less than 2.5 A from >> the battery at power levels I run. >> >> The battery is connected to a Xantrex RS-400 sine wave inverter. THD >> on the 60 Hz output is supposed to be < 3%. Looking at its output via >> a Tek 2465A scope shows a very clean sine wave, even under the max >> 400W load. The inverter is rated 400W, with surge to 800W. >> >> The inverter feeds an Astron SL-11A switching power supply that powers >> the K3/10. Its output is 13.6V, and under max load at the K3 we're >> talking about 2.8A, or 39W. >> >> All units described above are bond-grounded to each other using a 1/2" >> braided strap. The strap drops 10 feet or so to an 8 foot ground rod. >> The ground rod is also bonded to the house ground nearby. The house >> ground is used for all main and backup loads for a much larger Solar >> PV system that we use to power the house here. >> >> When using the Battery => Inverter => SL-11A power supply => K3 power >> supply path to power the radio, the switching supply hums quite a lot >> in weird non-periodic ways. I can sometimes hear the same hum on the >> K3 RX audio, but have had no reports of it showing up on TX audio when >> I asked the other party. "Very clean audio", they would always say. >> >> Given the long-winded narrative above, does anyone have an idea about >> the rx noise I'm hearing? Seems like it's not getting in through the >> DC, since it doesn't show on SSB TX. So maybe I'm hearing it over the >> air? >> >> I thought this might be common mode noise, but the TX reports I've got >> with this power supply setup won't support that. Grounding can affect >> that, but since low impedance paths are connecting all the inline >> stuff, this doesn't seem the easy answer either. >> >> Sorry to take up so much bandwidth, but it's possible another >> Elecrafter type might face a similar issue. So it seemed worth the >> bits. >> >> BTW, connecting the K3 directly to the 12V SLA battery has none of the >> above effects and works fine. Please - no flames over the easy >> answer, OK? :) >> >> 73 and thanks for any thoughts, >> >> matt zilmer, WA6EGJ >> K2 s/n 2810 >> K3 s/n 0024 >> >> >> _______________________________________________ >> Elecraft mailing list >> Post to: [hidden email] >> You must be a subscriber to post to the list. >> Subscriber Info (Addr. Change, sub, unsub etc.): >> http://mailman.qth.net/mailman/listinfo/elecraft >> >> Help: http://mailman.qth.net/subscribers.htm >> Elecraft web page: http://www.elecraft.com > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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I heard of this problem of instability when a second psu upset the first one
due to very high values of input capacitance. David G3UNA ----- Original Message ----- From: "Don Ehrlich" <[hidden email]> To: "Bill W5WVO" <[hidden email]>; <[hidden email]>; <[hidden email]> Sent: Saturday, November 17, 2007 5:29 PM Subject: Re: [Elecraft] K3 - Power supply question > My gut feel is that you may have some interaction between the > regulator/feedback loops in the inverter and switcher ... or the regulator > in the switcher is affected by the filtering of the inverter. I have seen > cases where perfectly well behaved power supplies (when operated alone, as > their designers usually intend) can start acting strangely when one power > supply feeds into another. The basic problem is feedback loop instability > due to one supply regulator being affected by a non-linear "active" load > presented to it by its load, which is another power supply. > > Just a thought. If this is the problem then a scope connected to the > input of the K3 might show some ripple due to the instability but not > necessarily so. Instability of this kind may not introduce much voltage > ripple at all at low impedance points. > > Don K7FJ > > >> Matt Zilmer wrote: >>> Hi to all, >>> >>> This is not a critical issue, but it might interest some. It's also >>> not necessarily specific to K3's. Keywords might be "switching power >>> supply", "inverter", and "grounding". >>> >>> The problem I describe below was never experienced with the K2, only >>> with the K3. I exchanged the two radios to confirm this >>> experimentally. >>> >>> The power supply scenario is as follows. >>> >>> Qty 2 - 50W Siemens solar panels on the roof above the shack supply a >>> 12V 100A-Hr SLA battery. The battery is charged through a Micro-X >>> charge controller, and this arrangement has been used for a few years >>> with my K2. It seems to work well under all conditions. The K2 is >>> the low power QRP version, and generally draws less than 2.5 A from >>> the battery at power levels I run. >>> >>> The battery is connected to a Xantrex RS-400 sine wave inverter. THD >>> on the 60 Hz output is supposed to be < 3%. Looking at its output via >>> a Tek 2465A scope shows a very clean sine wave, even under the max >>> 400W load. The inverter is rated 400W, with surge to 800W. >>> >>> The inverter feeds an Astron SL-11A switching power supply that powers >>> the K3/10. Its output is 13.6V, and under max load at the K3 we're >>> talking about 2.8A, or 39W. >>> >>> All units described above are bond-grounded to each other using a 1/2" >>> braided strap. The strap drops 10 feet or so to an 8 foot ground rod. >>> The ground rod is also bonded to the house ground nearby. The house >>> ground is used for all main and backup loads for a much larger Solar >>> PV system that we use to power the house here. >>> >>> When using the Battery => Inverter => SL-11A power supply => K3 power >>> supply path to power the radio, the switching supply hums quite a lot >>> in weird non-periodic ways. I can sometimes hear the same hum on the >>> K3 RX audio, but have had no reports of it showing up on TX audio when >>> I asked the other party. "Very clean audio", they would always say. >>> >>> Given the long-winded narrative above, does anyone have an idea about >>> the rx noise I'm hearing? Seems like it's not getting in through the >>> DC, since it doesn't show on SSB TX. So maybe I'm hearing it over the >>> air? >>> >>> I thought this might be common mode noise, but the TX reports I've got >>> with this power supply setup won't support that. Grounding can affect >>> that, but since low impedance paths are connecting all the inline >>> stuff, this doesn't seem the easy answer either. >>> >>> Sorry to take up so much bandwidth, but it's possible another >>> Elecrafter type might face a similar issue. So it seemed worth the >>> bits. >>> >>> BTW, connecting the K3 directly to the 12V SLA battery has none of the >>> above effects and works fine. Please - no flames over the easy >>> answer, OK? :) >>> >>> 73 and thanks for any thoughts, >>> >>> matt zilmer, WA6EGJ >>> K2 s/n 2810 >>> K3 s/n 0024 >>> >>> >>> _______________________________________________ >>> Elecraft mailing list >>> Post to: [hidden email] >>> You must be a subscriber to post to the list. >>> Subscriber Info (Addr. Change, sub, unsub etc.): >>> http://mailman.qth.net/mailman/listinfo/elecraft >>> >>> Help: http://mailman.qth.net/subscribers.htm >>> Elecraft web page: http://www.elecraft.com >> >> _______________________________________________ >> Elecraft mailing list >> Post to: [hidden email] >> You must be a subscriber to post to the list. >> Subscriber Info (Addr. Change, sub, unsub etc.): >> http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/subscribers.htm >> Elecraft web page: http://www.elecraft.com >> > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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