ASTRON PS and KX1
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Elecrafters,
While reading the thread re: charging batteries I saw the note re: adjusting the Astron. It occured to me that I could bump the ouput up from 13.8 to the "legal limit" for my KX1. The goal of course is "more power" out! Is this a bad idea? I say "bad" because I know that many will say that small increases in power are not of much value given the nature of decibels and the human hear, but unless this is a "bad" idea, I prefer to experiment and see what results I get! The ads for my RS-70M say it is adjustabe and my schematic shows a 20K ohm pot on the input to the V meter and a 500 ohm pot on the input to the I meter. I have not popped the top of the ps yet so I don't know what visual inspection will reveal. After I get some feedback on my idea I'll take a look and see what I can do! BTW, my Kenwood TS-570D specifies 13.8 VDC plus or minus 15%. This gives me a ceiling on 15.87. I am only going to 14.2 for KX1! I run them both of the RS-70M when I am operating from home. Thanks, Jack, AE6GC _______________________________________________ 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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On Nov 2, 2006, at 12:00 PM, Jack Regan wrote: > Elecrafters, > > > > While reading the thread re: charging batteries I saw the note re: > adjusting > the Astron. > > It occured to me that I could bump the ouput up from 13.8 to the > "legal > limit" for my KX1. The goal of course is "more power" out! > > > > Is this a bad idea? I say "bad" because I know that many will say > that > small increases in power are not of much value given the nature of > decibels > and the human hear, but unless this is a "bad" idea, I prefer to > experiment > and see what results I get! > > > > The ads for my RS-70M say it is adjustabe and my schematic shows a > 20K ohm > pot on the input to the V meter and a 500 ohm pot on the input to > the I > meter. I have not popped the top of the ps yet so I don't know > what visual > inspection will reveal. After I get some feedback on my idea I'll > take a > look and see what I can do! > > > > BTW, my Kenwood TS-570D specifies 13.8 VDC plus or minus 15%. This > gives me > a ceiling on 15.87. I am only going to 14.2 for KX1! I run them > both of > the RS-70M when I am operating from home. Those pots are for calibrating the meters and shouldn't be touched. There will be another pot which goes to pin 4 of the 723 ic which controls the voltage. I don't know how much voltage increase you can get by adjusting it, but suspect you should easily be able to set the supply for 14.2 volts. I set my Alinco DM-330 supply (front panel voltage adjusment) to 14.2 and it works fine that way with both my K2 and my TS-570D. Bob, N7XY _______________________________________________ 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 Jack Regan
Unless you're going to double your power, it's hardly worth the effort from
a technical point of view. Doubling the power raises you signal by what is considered by communications specialists to be a "just barely discernable change" in an on-air signal. (Yes, I know that is the definition of one decibel under audio laboratory conditions, but communications engineers have long used 3 dB or a 2:1 power change as the standard for a barely discernable change in "on air" conditions where there is some QSB, always some background QRN, etc. ) A 3 dB power change (2:1 change in power) is also about 1/2 of one S-unit on most meters. Sure, it's good practice to pursue good efficiency and take steps not to waste power, but the effect of a change like this are, at best, miniscule. Now if it stirs up the Mojo in the KX1 because it *feels* like it's getting out better with another half watt or so, that's another story. Ron AC7AC -----Original Message----- Elecrafters, While reading the thread re: charging batteries I saw the note re: adjusting the Astron. It occured to me that I could bump the ouput up from 13.8 to the "legal limit" for my KX1. The goal of course is "more power" out! Is this a bad idea? I say "bad" because I know that many will say that small increases in power are not of much value given the nature of decibels and the human hear, but unless this is a "bad" idea, I prefer to experiment and see what results I get! The ads for my RS-70M say it is adjustabe and my schematic shows a 20K ohm pot on the input to the V meter and a 500 ohm pot on the input to the I meter. I have not popped the top of the ps yet so I don't know what visual inspection will reveal. After I get some feedback on my idea I'll take a look and see what I can do! BTW, my Kenwood TS-570D specifies 13.8 VDC plus or minus 15%. This gives me a ceiling on 15.87. I am only going to 14.2 for KX1! I run them both of the RS-70M when I am operating from home. Thanks, Jack, AE6GC _ _______________________________________________ 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 Jack Regan
Jack,
The specification for the KX1 power is 7 to 14 volts with a recommendation of 8 volts minimum. So yes, you CAN increase the power supply voltage safely, but ask if it is really worth it. A typical KX1 will develop about 4 watts with a 14 volt power source, and 3.5 to 3.8 watts with 12 to 13.8 volts. There will also be an increase in heating of the output transistor and the case may feel a bit warmer to the touch. An increase of 0.5 watts (from 3.5 watts to 4.0 watts) is only 0.58 dB if my calculator did it right, and that small increase would not likely be noticable at the receiving end. The minimum change in power level that will increase communication effectiveness is considered 3 dB (only half an S-unit) - and that means doubling the power - so if your current power is 2 watts and increasing the voltage brings it to 4 watts, then that is worthwhile - anything less is not usually considered worth the expense nor the inconvenience. 73, Don W3FPR > -----Original Message----- > > While reading the thread re: charging batteries I saw the note > re: adjusting > the Astron. > > It occured to me that I could bump the ouput up from 13.8 to the "legal > limit" for my KX1. The goal of course is "more power" out! > > > > Is this a bad idea? I say "bad" because I know that many will say that > small increases in power are not of much value given the nature > of decibels > and the human hear, but unless this is a "bad" idea, I prefer to > experiment > and see what results I get! > > _______________________________________________ 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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