Power Supply Question
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I power my K2/100 with a Yaesu FP-1030A that also powers the FT-847.
Normally, it is on all the time. When leaving for an extended period a week or so ago, I turned it off, forgetting that I had a 12V Gel Cell floating on the output. When I got home, the voltmeter on the supply was at about 6V, and the supply won't turn on. Any ideas? I have a nearly free week and was hoping for some new ones with the K2. Fred K6DGW Auburn CA CM98lw K2 # 4398 KX1 # 897 _______________________________________________ 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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What's the battery voltage in the K2 with the power cable removed?
What's the P/S output voltage with all load removed? Do you have a schematic of the P/S? Do you have a scanner? Dan / WG4S / K2 #2456 -----Original Message----- From: [hidden email] [mailto:[hidden email]]On Behalf Of Fred Jensen Sent: Monday, December 12, 2005 5:57 PM To: Elecraft Reflector Subject: [Elecraft] Power Supply Question I power my K2/100 with a Yaesu FP-1030A that also powers the FT-847. Normally, it is on all the time. When leaving for an extended period a week or so ago, I turned it off, forgetting that I had a 12V Gel Cell floating on the output. When I got home, the voltmeter on the supply was at about 6V, and the supply won't turn on. Any ideas? I have a nearly free week and was hoping for some new ones with the K2. Fred K6DGW Auburn CA CM98lw K2 # 4398 KX1 # 897 _______________________________________________ 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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In reply to this post by k6dgw
By scanner, I meant an image scanner to scan the schematic. Since you don't
have a schematic, you don't need to scan it<g>. I've never seen a battery with recent use show 0 volts unless it's connected to something. If you disconnect it, it should show at least a few tenths of a volt. 0v on the P/S could be a fuse or breaker, but without a schematic it's going to be tough to troubleshoot by email. Some of the obvious things to check would be continuity from the leads to the circuit board, and wall voltage to a transformer, and inspect anthing that looks like a protection device to see no voltage drop across it. There may be something obvious, like a burnt part. If the battery really failed shorted, then turning on the PS should have popped a fuse, maybe even in your wiring from the PS to the load! Good luck. The schematic would really help. Google may help you find one. Dan / WG4S / K2 #2456 -----Original Message----- From: Fred Jensen [mailto:[hidden email]] Sent: Monday, December 12, 2005 6:51 PM To: Dan Barker Subject: Re: [Elecraft] Power Supply Question Dan Barker wrote: > What's the battery voltage in the K2 with the power cable removed? 0V. The battery is an external gel cell. I don't have the internal battery for my K2. > What's the P/S output voltage with all load removed? Right now it is 0V. It won't turn on. > Do you have a schematic of the P/S? No. I have the Yaesu manual, but there is only a block diagram of the PS. > Do you have a scanner? My 3 HT's scan, as does the FT-847 (if I could turn it on), but I don't have a broad spectrum scanner. Fred K6DGW _______________________________________________ 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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In reply to this post by k6dgw
Hi Fred,
Your PSU has probably suffered the same fate as our local 70cm repeater PSU did when we floated a battery across the output for emergencies. When the PSU was switched off it blew the DC fuse on the output of the PSU. The reason is the battery is capable of feeding enough power back into the PSU to exceed the current rating and rupture the output fuse which normally protects the PSU. The solution in our case was to fit a relay on the PSU DC output with it's coil powered from the AC supply. When the AC supply fails, the DC output link is cut off from the PSU. Not all PSU suffer this problem as we never had a problem with the 2m repeater with floating a large gel cell across that, but yours apparently did! Regards, Bob, G3VVT _______________________________________________ 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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In reply to this post by k6dgw
Fred,
If I understand properly, you still have the float battery connected. Try removing it and see if the power supply turns on. If that power supply has undervoltage protection, a discharged battery across its terminals will create an undervoltage situation and the power supply will shut down immediately. If that is the case, charge the battery from another supply before re-connecting it. I do hope your gel cell recovers, especially if it is a costly large one, but there is a chance that the low terminal voltage has significantly reduced its life and charge capacity. 73, Don W3FPR > -----Original Message----- > > I power my K2/100 with a Yaesu FP-1030A that also powers the FT-847. > Normally, it is on all the time. When leaving for an extended period a > week or so ago, I turned it off, forgetting that I had a 12V Gel Cell > floating on the output. When I got home, the voltmeter on the supply > was at about 6V, and the supply won't turn on. > > Any ideas? I have a nearly free week and was hoping for some new ones > with the K2. > > _______________________________________________ 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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In reply to this post by G3VVT
Diode.
Dan -----Original Message----- From: [hidden email] [mailto:[hidden email]]On Behalf Of [hidden email] Sent: Monday, December 12, 2005 8:59 PM To: [hidden email]; [hidden email] Subject: Re: [Elecraft] Power Supply Question Hi Fred, Your PSU has probably suffered the same fate as our local 70cm repeater PSU did when we floated a battery across the output for emergencies. When the PSU was switched off it blew the DC fuse on the output of the PSU. The reason is the battery is capable of feeding enough power back into the PSU to exceed the current rating and rupture the output fuse which normally protects the PSU. The solution in our case was to fit a relay on the PSU DC output with it's coil powered from the AC supply. When the AC supply fails, the DC output link is cut off from the PSU. Not all PSU suffer this problem as we never had a problem with the 2m repeater with floating a large gel cell across that, but yours apparently did! Regards, Bob, G3VVT _______________________________________________ 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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In reply to this post by k6dgw
Hi all,
A diode was my first try, but there are several problems with that approach. The first being the additional volt drop can make battery charging more of a problem with a fixed supply, though a schottky diode would help to some degree on that score. The biggest problem was the generation of heat was greater than would have comfortable with and there was not enough room within the PSU case to add the additional heat sinking required for the diode. However, the DC current requirements were rather higher for the repeater application than would be required to drive a basic K2. Yes, a diode could certainly be used with care. Bob, G3VVT _______________________________________________ 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 think you'll find that power Schottkys don't have any lower drop than a typical silicon rectifier. They are not like the Schottky signal diodes in that regard. Larry N8LP [hidden email] wrote: >Hi all, > >A diode was my first try, but there are several problems with that approach. > >The first being the additional volt drop can make battery charging more of a >problem with a fixed supply, though a schottky diode would help to some >degree on that score. The biggest problem was the generation of heat was greater >than would have comfortable with and there was not enough room within the PSU >case to add the additional heat sinking required for the diode. However, the >DC current requirements were rather higher for the repeater application than >would be required to drive a basic K2. > >Yes, a diode could certainly be used with care. > >Bob, G3VVT >_______________________________________________ >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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In reply to this post by G3VVT
This link might be helpful if your supply uses a UA723 regulator like
the Astron. It show an Astron schematic with a minor mod to allow float charging a battery without concern if the AC power fails. The mod involves cutting a circuit trace at pin 4 of the UA723 and bridging the break with a 10K resistor. https://ntc.cap.af.mil/images/rs-bat-mod.jpg Dick, K0KK [hidden email] wrote: >Hi all, > >A diode was my first try, but there are several problems with that approach. > > > > _______________________________________________ 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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