Re: [Elecraft] Linear PS Recommendations
> If Alan is reading this, I'm wondering if I missed where that > 'strategically placed diode' is located? One way to do it is just to put a pair of back-to-back diodes in parallel with the inputs. That protects against over-voltage of either polarity. One thing I always like to do when constructing a homebrew project is to paste a copy of the schematic inside the top cover. That way I can never lose the schematic. :=) Here's an image of such a schematic of a 723-based, 10A, 7-15V bench supply that I built many years ago: http://n1al.net/music/N1AL_10A.gif It is very conservatively rated at 10A. I probably could have designed it for a comfortable 15A, but the markings on the meter I wanted to use for an ammeter wouldn't easily accommodate that. For a similar reason, I put a 5V zener in series with the voltmeter so it would read 5-15. One issue with the 723 is that it needs a higher-voltage supply than the pass transistors. If you make the unregulated input voltage high enough to avoid dropout, the pass transistors are dissipating more power than they need to. So in this design I used a separate supply for the 723. One issue with doing that is if the transistor supply fails (it is separately fused) the 723 tries to supply all the output current. In this case the 723 supply is derived from 65V (since that was the available winding on the transformer I used) with a dropping resistor and shunt zener. The dropping resistor limits the current to a safe value. This supply has fold-back current limiting. The 22k resistor from pin 2 causes the current limit to drop from 14A or so at 13.8V output to about 11A at 7V output and 7A with a short circuit. That's a good idea for a variable-voltage supply since pass transistor dissipation increases at lower output voltages. But even for a fixed-voltage supply it's nice that the supply recovers automatically from a shorted output. If you use a crowbar-type current limit, you have to cycle power to get it to turn on again. Alan N1AL On 07/22/2016 11:46 PM, Richard Fjeld wrote: Hello David, (and Alan), and thanks to John for the link showing the added parts. David, your PS sounds very similar to the one I built, also in the 70's. Mine has four 3055's on very large heat sinks that are overkill, but I didn't know what to expect. It was at a time when we were going from high voltage PS for tubes to Low voltage PS for solid state. I had not seen a low voltage supply to power a 100 watt rig yet. So I went heavy duty. My diodes for the full wave bridge I made were stud mounted on 1/4 inch aluminum pieces for heat sinking, and mounted on wood to insulate them from each other. There were no full wave bridges in a package yet. I'm curious how your supply trips out, and if you used a relay? It seems to me that I did that, and when the 723 clamps down, the relay drops to open the primary. I have not had the time to review the schematic diagram, but as I recall, if a pass transistor shorts out, the crowbar may try to shunt the unregulated voltage, but the situation is not going to be good. That is why I like the device ad5x is showing on his website. It will protect the radio from over-voltage by blowing a fuse in the DC line. If Alan is reading this, I'm wondering if I missed where that 'strategically placed diode' is located? Dick, n0ce On 7/22/2016 10:16 AM, David Anderson via Elecraft wrote: I have a couple of homebuilt DC regulated supplies that I built a great many years ago, the first is a simple 3A 13.5V one that was the very first supply I ever built and it used a 723 with a single 2N3055 series pass transistor. I remember I bought a lovely oil filled mains transformer for it, but accidentally wired up the 120V windings in parallel instead of series for our 240V mains and watched it start to bulge when I switched it on. (after I put a bigger fuse in it). I ended up using another transformer and the power supply is still in daily use, built in the early 70's. I later built a 25 Amp version with 4 3055s and a 723 with overvoltage trip, and also short circuit protection. It can be shorted out and with barely a spark it trips out and has to be reset before it comes on again. No fuses to blow and replace, no destroyed series pass transistors. I built it in a chassis that was lying around and 35 years later it is still in daily use and still not got a proper cover made for the chassis. I checked the output the other day on my scope to see if there was any hum or ripple and on full load I had 10mV p-p of noise. Regulation still excellent. Nothing much wrong with the humble 723. I have seen some truly awful "commercial" supplies with no short circuit protection, that blow the series pass transistors like fuses, or worse make them into short circuits that apply the full unregulated supply on to the load. 73 from David GM4JJJ On 22 Jul 2016, at 15:55, Alan Bloom wrote: The 723 regulator has some known relia
Re: [Elecraft] Linear PS Recommendations
Richard, After a big search through my old documentation I have found all my design notes on the power supplies I built, I still have the Fairchild voltage regulator application handbook that I consulted at the time. Like you, I needed to build this supply for my first solid state high power equipment and I still use it to this day. The smoothing electrolytics are 2 large 31,000 uF military standard capacitors which were used in battlefield computers. The short circuit protection of the 25 Amp power supply appears to be something that I "designed" as it doesn't appear in the handbook in the form I used. Basically it uses a transistor that senses the output voltage dropping (as it would with a short circuit on the output) and this then triggers a small SCR which pulls the 723 compensation pin low which makes the 723 output voltage stop. This will remain like that until the short circuit is removed and the current through the SCR is broken by manually pushing a NC switch in series with the SCR. It works well, I have used it to zap NICADS that have gone short circuit! It just gives a brief pulse of high current and trips the supply, no fuse blowing etc. Overvoltage protection is even cruder, it is a standard Crowbar circuit with very big 40 amp SCR and 16 V zener to sense. This will blow a 20 Amp fuse in the raw supply. It has never been used in anger, though I did test it with a smaller fuse. It is there only to protect against either a shorted pass transistor or some fault with the regulator circuitry. Of course having a good current limit circuit with short circuit protection makes the likelihood of a series pass transistor failing short circuit more unlikely. My design has 4 2N3055's in parallel (with low value resistors in the emitters to help share the current equally) driven by another 3055, the current sense resistor is in the base drive of the output series pass transistors. I have over temperature protection of the transformer with a bimetallic switch but that has never tripped. I do have a soft start circuit on the primary using an AC relay and some high wattage resistors. I avoided using fans by using large heatsinks as fans are a source of failure over time. [I recall a commercial 5V 80 amp supply cooling fan failing at night, the supply shutting down for over temperature then coming back on again, rinse and repeat, until nearly every IC in a multimillion $ machine was damaged.] Like so many projects this was developed from earlier projects, starting with a simple single transistor 3A PSU, then an 8A using more transistors, and finally the 25A supply with much more in the way of protection from likely fault conditions. I am not sure I could source the mains transformer or smoothing capacitors so easily nowadays if I wanted to build another one, as nearly all new designs are high efficiency switched mode supplies. I think it best if anyone else wants more details that they take this off the list and contact me directly as we are well over the limit on postings on this subject. 73 from David GM4JJJ > On 23 Jul 2016, at 07:46, Richard Fjeld wrote: > > Hello David, (and Alan), and thanks to John for the link showing the added > parts. > > David, your PS sounds very similar to the one I built, also in the 70's. > Mine has four 3055's on very large heat sinks that are overkill, but I didn't > know what to expect. > > I'm curious how your supply trips out, and if you used a relay? It seems to > me that I did that, and when the 723 clamps down, the relay drops to open the > primary. I have not had the time to review the schematic diagram, but as I > recall, if a pass transistor shorts out, the crowbar may try to shunt the > unregulated voltage, but the situation is not going to be good. That is why > I like the device ad5x is showing on his website. It will protect the radio > from over-voltage by blowing a fuse in the DC line. > > If Alan is reading this, I'm wondering if I missed where that 'strategically > placed diode' is located? > > Dick, n0ce > > >> On 7/22/2016 10:16 AM, David Anderson via Elecraft wrote: >> >> I later built a 25 Amp version with 4 3055s and a 723 with overvoltage trip, >> and also short circuit protection. It can be shorted out and with barely a >> spark it trips out and has to be reset before it comes on again. No fuses to >> blow and replace, no destroyed series pass transistors. I built it in a >> chassis that was lying around and 35 years later it is still in daily use >> and still not got a proper cover made for the chassis. I checked the output >> the other day on my scope to see if there was any hum or ripple and on full >> load I had 10mV p-p of noise. Regulation still excellent. >> >> >> 73 from David GM4JJJ >> >>> On 22 Jul 2016, at 15:55, Alan Bloom wrote: >>> >>> The 723 regulator has some known reliability issues, but with proper design >>> they can be mitigated. In partic
Re: [Elecraft] Linear PS Recommendations
Hello David, (and Alan), and thanks to John for the link showing the added parts. David, your PS sounds very similar to the one I built, also in the 70's. Mine has four 3055's on very large heat sinks that are overkill, but I didn't know what to expect. It was at a time when we were going from high voltage PS for tubes to Low voltage PS for solid state. I had not seen a low voltage supply to power a 100 watt rig yet. So I went heavy duty. My diodes for the full wave bridge I made were stud mounted on 1/4 inch aluminum pieces for heat sinking, and mounted on wood to insulate them from each other. There were no full wave bridges in a package yet. I'm curious how your supply trips out, and if you used a relay? It seems to me that I did that, and when the 723 clamps down, the relay drops to open the primary. I have not had the time to review the schematic diagram, but as I recall, if a pass transistor shorts out, the crowbar may try to shunt the unregulated voltage, but the situation is not going to be good. That is why I like the device ad5x is showing on his website. It will protect the radio from over-voltage by blowing a fuse in the DC line. If Alan is reading this, I'm wondering if I missed where that 'strategically placed diode' is located? Dick, n0ce On 7/22/2016 10:16 AM, David Anderson via Elecraft wrote: I have a couple of homebuilt DC regulated supplies that I built a great many years ago, the first is a simple 3A 13.5V one that was the very first supply I ever built and it used a 723 with a single 2N3055 series pass transistor. I remember I bought a lovely oil filled mains transformer for it, but accidentally wired up the 120V windings in parallel instead of series for our 240V mains and watched it start to bulge when I switched it on. (after I put a bigger fuse in it). I ended up using another transformer and the power supply is still in daily use, built in the early 70's. I later built a 25 Amp version with 4 3055s and a 723 with overvoltage trip, and also short circuit protection. It can be shorted out and with barely a spark it trips out and has to be reset before it comes on again. No fuses to blow and replace, no destroyed series pass transistors. I built it in a chassis that was lying around and 35 years later it is still in daily use and still not got a proper cover made for the chassis. I checked the output the other day on my scope to see if there was any hum or ripple and on full load I had 10mV p-p of noise. Regulation still excellent. Nothing much wrong with the humble 723. I have seen some truly awful "commercial" supplies with no short circuit protection, that blow the series pass transistors like fuses, or worse make them into short circuits that apply the full unregulated supply on to the load. 73 from David GM4JJJ On 22 Jul 2016, at 15:55, Alan Bloom wrote: The 723 regulator has some known reliability issues, but with proper design they can be mitigated. In particular the differential voltage on the error amplifier inputs is only rated for 5v. If one input is connected to the 7.15V reference, then if the power supply output is shorted the voltage rating is exceeded. The solution is a strategically-placed diode. Alan N1AL __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Linear PS Recommendations
I have a couple of homebuilt DC regulated supplies that I built a great many years ago, the first is a simple 3A 13.5V one that was the very first supply I ever built and it used a 723 with a single 2N3055 series pass transistor. I remember I bought a lovely oil filled mains transformer for it, but accidentally wired up the 120V windings in parallel instead of series for our 240V mains and watched it start to bulge when I switched it on. (after I put a bigger fuse in it). I ended up using another transformer and the power supply is still in daily use, built in the early 70's. I later built a 25 Amp version with 4 3055s and a 723 with overvoltage trip, and also short circuit protection. It can be shorted out and with barely a spark it trips out and has to be reset before it comes on again. No fuses to blow and replace, no destroyed series pass transistors. I built it in a chassis that was lying around and 35 years later it is still in daily use and still not got a proper cover made for the chassis. I checked the output the other day on my scope to see if there was any hum or ripple and on full load I had 10mV p-p of noise. Regulation still excellent. Nothing much wrong with the humble 723. I have seen some truly awful "commercial" supplies with no short circuit protection, that blow the series pass transistors like fuses, or worse make them into short circuits that apply the full unregulated supply on to the load. 73 from David GM4JJJ > On 22 Jul 2016, at 15:55, Alan Bloom wrote: > > The 723 regulator has some known reliability issues, but with proper design > they can be mitigated. In particular the differential voltage on the error > amplifier inputs is only rated for 5v. If one input is connected to the > 7.15V reference, then if the power supply output is shorted the voltage > rating is exceeded. The solution is a strategically-placed diode. > > Alan N1AL > > __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Linear PS Recommendations
The 723 regulator has some known reliability issues, but with proper design they can be mitigated. In particular the differential voltage on the error amplifier inputs is only rated for 5v. If one input is connected to the 7.15V reference, then if the power supply output is shorted the voltage rating is exceeded. The solution is a strategically-placed diode. Alan N1AL On 07/22/2016 12:14 AM, Richard Fjeld wrote: I was glad that I caught Jim's remark about blowing the 723 by being connected to a battery with the PS off. And also Myron's answer. Back in the tube TV days, I purchased a bare circuit board at Radio Shack, (I think). The board was similar to an Astron circuit board, but simpler. I rewound a heavy transformer from a color TV and made my first 13.8 Volt power supply to use for a Heathkit HW-104. Years later, the 723 went bad. It may have been due to the stated reason, I can't remember now. I did some repair work on it and still have it. Someone on the reflector provided the following link one time, which I think is a good idea for an extra measure of over-voltage protection or accidental reversal in polarity. I remember discussion about a reversal that happened to someone on the reflector not long ago. I hope the link still works on here. If it doesn't, it is on ad5x dot com website. Look for a Vprotect pdf file. http://ad5x.com/images/Articles/Vprotect.pdf Dick, n0ce On 7/21/2016 7:41 AM, Myron Schaffer wrote: Jim and Clay, It used to be that waythe RS linear models could not tolerate external voltage present when unpowered, not anymore. Astron has incorporated back-voltage protection through incorporation of some diodes installed in key locations to prevent this. You can verify if your supply has this modification by looking at the circuit board and see a 1N4001 type diode soldered across 2-pins (can't remember which ones off the top of my head) of the IC voltage regulator LM-723 chip and others hung in various places to protect the pass transistor as well. Usually soldered to the solder side of the circuit board so they are easy to spot. I can't remember is there were some small capacitors added as well. Any newer (like newer than 1990) linear Astron will have these installed. Myron WVØH Printed on Recycled Data - __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to n...@sonic.net __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Linear PS Recommendations
Hi All, Here is a link to a schematic for the 3/4 A power supplies with the added parts for external voltage protection: http://www.ameradio.com/doc/Astron%20RS-3A,%20RS-4A%20schematic.pdf John KN5L On 07/21/2016 07:41 AM, Myron Schaffer wrote: > It used to be that waythe RS linear models could not tolerate external > voltage present when unpowered, not anymore. Astron has incorporated > back-voltage protection through incorporation of some diodes installed in key > locations to prevent this. > > You can verify if your supply has this modification by looking at the circuit > board and see a 1N4001 type diode soldered across 2-pins (can't remember > which ones off the top of my head) of the IC voltage regulator LM-723 chip > and others hung in various places to protect the pass transistor as well. > Usually soldered to the solder side of the circuit board so they are easy to > spot. I can't remember is there were some small capacitors added as well. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Linear PS Recommendations
I was glad that I caught Jim's remark about blowing the 723 by being connected to a battery with the PS off. And also Myron's answer. Back in the tube TV days, I purchased a bare circuit board at Radio Shack, (I think). The board was similar to an Astron circuit board, but simpler. I rewound a heavy transformer from a color TV and made my first 13.8 Volt power supply to use for a Heathkit HW-104. Years later, the 723 went bad. It may have been due to the stated reason, I can't remember now. I did some repair work on it and still have it. Someone on the reflector provided the following link one time, which I think is a good idea for an extra measure of over-voltage protection or accidental reversal in polarity. I remember discussion about a reversal that happened to someone on the reflector not long ago. I hope the link still works on here. If it doesn't, it is on ad5x dot com website. Look for a Vprotect pdf file. http://ad5x.com/images/Articles/Vprotect.pdf Dick, n0ce On 7/21/2016 7:41 AM, Myron Schaffer wrote: Jim and Clay, It used to be that waythe RS linear models could not tolerate external voltage present when unpowered, not anymore. Astron has incorporated back-voltage protection through incorporation of some diodes installed in key locations to prevent this. You can verify if your supply has this modification by looking at the circuit board and see a 1N4001 type diode soldered across 2-pins (can't remember which ones off the top of my head) of the IC voltage regulator LM-723 chip and others hung in various places to protect the pass transistor as well. Usually soldered to the solder side of the circuit board so they are easy to spot. I can't remember is there were some small capacitors added as well. Any newer (like newer than 1990) linear Astron will have these installed. Myron WVØH Printed on Recycled Data - __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Linear PS Recommendations
I blew up the LM-723 in my old Astron VS-35M by trying to use it as a battery charger quite a few years ago (I bought the Astron to power my TS-180S in 1981). A year ago it failed to output and blew the fuses. Turned out one of the rectifiers shorted. I replaced both and its working fine as workbench PS. I guessed the output pass regulator transistors shorted so bought four. Now I have four spares (2016-1981 = 35 years and counting). My workplace (retired seven years) used a bunch of Basecom-20 which were identical to Astron RS-20A which all used the LM-723. My guess Astron markets a lot of PS that are relabeled. I use a 50A PS for powering my station (Has TAIT Two-way Radio label but meters are labeled Astron; guessing RS-50M). It maintains a charge on a 17AH gel-cell which I use to power by station 10-MHz OCXO reference. It's run 24/7 for years. Much newer than the VS-35M. 73, Ed - KL7UW http://www.kl7uw.com "Kits made by KL7UW" Dubus Mag business: dubus...@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Linear PS Recommendations
Thanks Myron... Haven't cracked the case yet, but will check and verify... __ Clay Autery, KY5G MONTAC Enterprises (318) 518-1389 On 7/21/2016 7:41 AM, Myron Schaffer wrote: > Jim and Clay, > > It used to be that waythe RS linear models could not tolerate external > voltage present when unpowered, not anymore. Astron has incorporated > back-voltage protection through incorporation of some diodes installed in key > locations to prevent this. > > You can verify if your supply has this modification by looking at the circuit > board and see a 1N4001 type diode soldered across 2-pins (can't remember > which ones off the top of my head) of the IC voltage regulator LM-723 chip > and others hung in various places to protect the pass transistor as well. > Usually soldered to the solder side of the circuit board so they are easy to > spot. I can't remember is there were some small capacitors added as well. > > Any newer (like newer than 1990) linear Astron will have these installed. > > Myron WVØH > Printed on Recycled Data __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Linear PS Recommendations
Boy, talk about LONNNGG life. The µ723 regulator IC has been around almost as long as 811-A's ! Wasn't it introduced by Fairchild in the 60's? I wonder how many ( XX thousands ??) of power supplies have been designed around it. 73, Charlie k3ICH -Original Message- From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Myron Schaffer Sent: Thursday, July 21, 2016 8:42 AM To: j...@audiosystemsgroup.com Cc: elecraft@mailman.qth.net Subject: Re: [Elecraft] Linear PS Recommendations Jim and Clay, It used to be that waythe RS linear models could not tolerate external voltage present when unpowered, not anymore. Astron has incorporated back-voltage protection through incorporation of some diodes installed in key locations to prevent this. You can verify if your supply has this modification by looking at the circuit board and see a 1N4001 type diode soldered across 2-pins (can't remember which ones off the top of my head) of the IC voltage regulator LM-723 chip and others hung in various places to protect the pass transistor as well. Usually soldered to the solder side of the circuit board so they are easy to spot. I can't remember is there were some small capacitors added as well. Any newer (like newer than 1990) linear Astron will have these installed. Myron WVØH Printed on Recycled Data > On Jul 21, 2016, at 12:10 AM, Jim Brown wrote: > >> On Wed,7/20/2016 10:52 PM, Bob Nielsen wrote: >> you probably don't need much more than 20 amp capability. I have used an >> Astron RS-20 for the past 35 years but I would probably go for the RS-35 or >> RS-50 if I was getting another one. > > That depends on what gear other than the radio that you want to run from it, > and whether it is charging a battery which runs the gear or the supply is > running the gear directly. It's easy for other 12V gear in a shack to add > several amps to the load, and the fancier the shack gets, the more that > increases. Clay said he wanted to run all his gear from it (but not the KPA, > I am assuming, because it's 120/240V powered). The gear I saw included > computer monitors, a K-Line, and some accessories. Perhaps there will someday > be antenna relays. And so on. > > Also, the numbers in Astron's model names do NOT correspond to steady state > load capacity. It's important to study the data sheets. They are generally > well regarded for reliability, but every one I've opened had a bonding > problem which is important, but easy to fix. > > Another important characteristic of Astron supplies is that their output > regulator circuit is likely to fry if connected to charge a battery but the > supply is not powered. Like in a power failure. Ask me how I know this. :) > Astron sells a module to place between the supply and the battery to solve > this problem. > > 73, Jim K9YC > > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net Please help support this email > list: http://www.qsl.net/donate.html Message delivered to > thelas...@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to pin...@erols.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Linear PS Recommendations
Jim and Clay, It used to be that waythe RS linear models could not tolerate external voltage present when unpowered, not anymore. Astron has incorporated back-voltage protection through incorporation of some diodes installed in key locations to prevent this. You can verify if your supply has this modification by looking at the circuit board and see a 1N4001 type diode soldered across 2-pins (can't remember which ones off the top of my head) of the IC voltage regulator LM-723 chip and others hung in various places to protect the pass transistor as well. Usually soldered to the solder side of the circuit board so they are easy to spot. I can't remember is there were some small capacitors added as well. Any newer (like newer than 1990) linear Astron will have these installed. Myron WVØH Printed on Recycled Data > On Jul 21, 2016, at 12:10 AM, Jim Brown wrote: > >> On Wed,7/20/2016 10:52 PM, Bob Nielsen wrote: >> you probably don't need much more than 20 amp capability. I have used an >> Astron RS-20 for the past 35 years but I would probably go for the RS-35 or >> RS-50 if I was getting another one. > > That depends on what gear other than the radio that you want to run from it, > and whether it is charging a battery which runs the gear or the supply is > running the gear directly. It's easy for other 12V gear in a shack to add > several amps to the load, and the fancier the shack gets, the more that > increases. Clay said he wanted to run all his gear from it (but not the KPA, > I am assuming, because it's 120/240V powered). The gear I saw included > computer monitors, a K-Line, and some accessories. Perhaps there will someday > be antenna relays. And so on. > > Also, the numbers in Astron's model names do NOT correspond to steady state > load capacity. It's important to study the data sheets. They are generally > well regarded for reliability, but every one I've opened had a bonding > problem which is important, but easy to fix. > > Another important characteristic of Astron supplies is that their output > regulator circuit is likely to fry if connected to charge a battery but the > supply is not powered. Like in a power failure. Ask me how I know this. :) > Astron sells a module to place between the supply and the battery to solve > this problem. > > 73, Jim K9YC > > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to thelas...@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Linear PS Recommendations
That would have been my recommendation. I discovered a couple of weeks ago that I had a new-in-box RS-35M in my storage shed that I bought for a spare 20+ years ago. Never needed it. Fired it up just for the heck of it and it's FB. On 7/21/2016 2:24 AM, Clay Autery wrote: Thanks Jim! Yes, eventually there will be quite a collection of gear. My #1 Elmer showed up at my door and surprised me with a NICE RS-35M to get me off that SMPS. It is super quiet. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Linear PS Recommendations
Thanks Jim! Yes, eventually there will be quite a collection of gear. My #1 Elmer showed up at my door and surprised me with a NICE RS-35M to get me off that SMPS. It is super quiet. I haven't opened it up yet, but I know (from one of your papers) what to look for. And I suspect my Elmer has already gone over this unit with a fine-toothed comb. He's an old Motorola and Air Force comms tech. Eventually, I DO plan to power the entire shack from batteries and am considering modifying linear supplies to provide the DC to the charger controller(s). I will probably use the PWRGate as an interim solution as per Kevin's reiterated "OK" via email today... Have a lot on my plate to complete before I get to that... Just got a "new" (to me) HP 5335A today, so I need to back up and cal the radio while I wait on the rest of the sub-panel project parts to arrive. And I am cooperating with Elecraft (and hopefully Powerwerx) to figure out how to mitigate the problems with the switcher supply. (Sounds like reverse current through the regulator circuit almost smoked my fan controller because I almost forgot to protect against this when switching to the 12VDC input from the 13.8VDC input... 73, __ Clay Autery, KY5G MONTAC Enterprises (318) 518-1389 On 7/21/2016 1:10 AM, Jim Brown wrote: > On Wed,7/20/10:52 PM, Bob Nielsen wrote: >> you probably don't need much more than 20 amp capability. I have used >> an Astron RS-20 for the past 35 years but I would probably go for the >> RS-35 or RS-50 if I was getting another one. > > That depends on what gear other than the radio that you want to run > from it, and whether it is charging a battery which runs the gear or > the supply is running the gear directly. It's easy for other 12V gear > in a shack to add several amps to the load, and the fancier the shack > gets, the more that increases. Clay said he wanted to run all his gear > from it (but not the KPA, I am assuming, because it's 120/240V > powered). The gear I saw included computer monitors, a K-Line, and > some accessories. Perhaps there will someday be antenna relays. And so > on. > > Also, the numbers in Astron's model names do NOT correspond to steady > state load capacity. It's important to study the data sheets. They are > generally well regarded for reliability, but every one I've opened had > a bonding problem which is important, but easy to fix. > > Another important characteristic of Astron supplies is that their > output regulator circuit is likely to fry if connected to charge a > battery but the supply is not powered. Like in a power failure. Ask me > how I know this. :) Astron sells a module to place between the supply > and the battery to solve this problem. > > 73, Jim K9YC > > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to caut...@montac.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Linear PS Recommendations
On Wed,7/20/2016 10:52 PM, Bob Nielsen wrote: you probably don't need much more than 20 amp capability. I have used an Astron RS-20 for the past 35 years but I would probably go for the RS-35 or RS-50 if I was getting another one. That depends on what gear other than the radio that you want to run from it, and whether it is charging a battery which runs the gear or the supply is running the gear directly. It's easy for other 12V gear in a shack to add several amps to the load, and the fancier the shack gets, the more that increases. Clay said he wanted to run all his gear from it (but not the KPA, I am assuming, because it's 120/240V powered). The gear I saw included computer monitors, a K-Line, and some accessories. Perhaps there will someday be antenna relays. And so on. Also, the numbers in Astron's model names do NOT correspond to steady state load capacity. It's important to study the data sheets. They are generally well regarded for reliability, but every one I've opened had a bonding problem which is important, but easy to fix. Another important characteristic of Astron supplies is that their output regulator circuit is likely to fry if connected to charge a battery but the supply is not powered. Like in a power failure. Ask me how I know this. :) Astron sells a module to place between the supply and the battery to solve this problem. 73, Jim K9YC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Linear PS Recommendations
Since the KPA500 has its own linear supply, you probably don't need much more than 20 amp capability. I have used an Astron RS-20 for the past 35 years but I would probably go for the RS-35 or RS-50 if I was getting another one. 73, Bob N7XY On 7/20/16 5:57 PM, Clay Autery wrote: I am looking for recommendations for a linear power supply to power my shack. Right this minute I need one just for my K3s and P3, but at some point will be adding a KPA500, KAT500, dual monitors, etc. Also, looking at building a dummy battery to run my laptop off the shack supply (11.1VDC, so a linear reg built into the dummy). I will have plenty of power soon... 40 Amp 220 VAC sub-panel going in with 8 x 20A 120, 1x 15Amp 220, 1 x 20A 220 (yes, I know the sub branches total more than the sub-IN... total up the breakers in your main service). The wiring is such that I can up it to 60 Amps if/when I "need" it. I just can't deal with this SMPS anymore... Ran one net on battery power and it was like a different world. At some point, I will run on batteries 100%, but will still need a nice quiet hoss of a linear to feed the charge controller(s). 73, __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
[Elecraft] Linear PS Recommendations
I am looking for recommendations for a linear power supply to power my shack. Right this minute I need one just for my K3s and P3, but at some point will be adding a KPA500, KAT500, dual monitors, etc. Also, looking at building a dummy battery to run my laptop off the shack supply (11.1VDC, so a linear reg built into the dummy). I will have plenty of power soon... 40 Amp 220 VAC sub-panel going in with 8 x 20A 120, 1x 15Amp 220, 1 x 20A 220 (yes, I know the sub branches total more than the sub-IN... total up the breakers in your main service). The wiring is such that I can up it to 60 Amps if/when I "need" it. I just can't deal with this SMPS anymore... Ran one net on battery power and it was like a different world. At some point, I will run on batteries 100%, but will still need a nice quiet hoss of a linear to feed the charge controller(s). 73, -- __ Clay Autery, KY5G MONTAC Enterprises (318) 518-1389 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
