Greg T
WDX-945 (Jazz Singer) Upper Peninsula of Michigan
Use a Megawatt and you'll have no noise.
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Home power supply for linear amp - ever used one of these type?
- Thread starter ShakyMcQuiver
- Start date
I have PM 100 amp about 10 years old now and never failed me yet.Here is the one I just bought which might cost a little more but it is sold by a Ham Supply store so I'm hoping has less noise and/or harmonics.
Here is a link on the forum here where they discuss this issue with cheap and/or knock off's from China.
MegaWatt vs. Chinese Imitation 30 amp switching power supply comparison
In an earlier thread about the various switching power supplies available on Amazon, there were questions posted about the difference between the authentic American made MegaWatt 30 amp supply and the cheaper Chinese imitation supply. I've purchased both supplies and used them extensively with...
In 1993 in college I used a switcher because I was living in dorms and or apartments. Luging a linear steel core supply was expensive and awkward. I had to move out of the dorms ever 10 weeks. A 35A switcher powered my RCI2950 and 1 to 2 transistor amp just fine.
It was common for guys to use deep cycle batteries and an actual battery charger not mainter in the 1980's and very early 1990's but as switchers come on the market they disappeared quickly.
Today with the advent of cheap chinese made switchers no one in a home environment uses batteries much today it went from fairly common to rather rare.
I much prefer people have 1 switcher for the radio and 1 or more for amp if going cheap on the switching supply.
If we are talking about old school bipolar amp then figure on needing ball park 20A per transistor assuming you are not a made man running his gear to the raged edge.
Most power supplies marketed as 12V are actually 13.8 nominal and most will be adjustable from 12.5 to 15 volts. The thing is most of them if not all of them the rated amperage drops as you turn up the voltage. So if it is say rated at 35A@12.5 volts and you crank it to 14.8 it might only get to 25A before it trips the protection circuit.
On the topic of harming anything no it will not harm anything to be at 12.5V instead of higher. You will produce less power and draw more current as the voltage decreases. That said with the demise of the American made and Japanese made transistors the Chinese made ones of today really can not live long lives at 15V or above on a 12V to 13.8V device. Gone are the days of running 18V-26V into a Toshiba 2SC2879 while shouting something stupid like "Worldwide...Worldwide..Worldwide". Likewise the days of driving the snot out of a big box with music for 5+ minutes are gone as well if you have a box with Chinese transistors in it! Well that is assuming you want it to last!
Also the last 3 years have been hard on all things radio related and the rating on cheap chinese supplies is not to be trusted. A current cheap 40A supply is maybe a 20A continuous supply where just 2 years ago the rating on the supply was fairly accurate!
With a the advent of Chinese smps it pays to get double the continuous rated power as you actual need. Just like when I spec out materials for anything I am going to have made in Mainland China I specify a higher grade material than I actual need knowing they will cheapen the specifications. Keep in mind the rating on these units are surge not continuous!
It was common for guys to use deep cycle batteries and an actual battery charger not mainter in the 1980's and very early 1990's but as switchers come on the market they disappeared quickly.
Today with the advent of cheap chinese made switchers no one in a home environment uses batteries much today it went from fairly common to rather rare.
I much prefer people have 1 switcher for the radio and 1 or more for amp if going cheap on the switching supply.
If we are talking about old school bipolar amp then figure on needing ball park 20A per transistor assuming you are not a made man running his gear to the raged edge.
Most power supplies marketed as 12V are actually 13.8 nominal and most will be adjustable from 12.5 to 15 volts. The thing is most of them if not all of them the rated amperage drops as you turn up the voltage. So if it is say rated at 35A@12.5 volts and you crank it to 14.8 it might only get to 25A before it trips the protection circuit.
On the topic of harming anything no it will not harm anything to be at 12.5V instead of higher. You will produce less power and draw more current as the voltage decreases. That said with the demise of the American made and Japanese made transistors the Chinese made ones of today really can not live long lives at 15V or above on a 12V to 13.8V device. Gone are the days of running 18V-26V into a Toshiba 2SC2879 while shouting something stupid like "Worldwide...Worldwide..Worldwide". Likewise the days of driving the snot out of a big box with music for 5+ minutes are gone as well if you have a box with Chinese transistors in it! Well that is assuming you want it to last!
Also the last 3 years have been hard on all things radio related and the rating on cheap chinese supplies is not to be trusted. A current cheap 40A supply is maybe a 20A continuous supply where just 2 years ago the rating on the supply was fairly accurate!
With a the advent of Chinese smps it pays to get double the continuous rated power as you actual need. Just like when I spec out materials for anything I am going to have made in Mainland China I specify a higher grade material than I actual need knowing they will cheapen the specifications. Keep in mind the rating on these units are surge not continuous!
Yes but the way in which most do it is not safe, durable or correct. You can actual purchase power supplies designed to be paralleled that have a master/slave setting just like a hard drive and they have a command line is daisy chained so that one unit commands them all. The load sensing on a switcher is ont he negative side. Just placing a strap across the cases is not the right way to get this done!
It cost more to do it properly but when you look at the fact that most of you guys have a $400+ Stryker 955 and are running amps with $250+ per transistor Toshiba boxes and the cost of quality coax doing your power supply properly is cheap!
How many video's have we watched from "builders" doing this wrong and it never fails someone has a almost brand new 6, 8, 12 pill "base" am and 2 or more switchers are bad. All the time and money and risk of further lose or damage in shipping when it could have been prevented in large part.
Buy once cry once!
Not used a PowerMax but I know plenty of people who have. CB is rather lucky because most of the noise most of these switchers make is not on 11m band. Notice I said "most"!
I have used Samlex(sp) for a long time. A few years ago I purchased a bunch of server supplies NOS. I have a bunch of 80A, 60A and 30A units and those are continuous rating not surge. When I say continuous I do mean 24/7 for years no problem! Some of them you can get up to 14V some of them anything more than 12.8 and they trip the protection circuit. I was getting these though off of Ebay for like $24 or less brand new and free shipping.
They are not plug and play though you have to do a little bit of work.
I have used Samlex(sp) for a long time. A few years ago I purchased a bunch of server supplies NOS. I have a bunch of 80A, 60A and 30A units and those are continuous rating not surge. When I say continuous I do mean 24/7 for years no problem! Some of them you can get up to 14V some of them anything more than 12.8 and they trip the protection circuit. I was getting these though off of Ebay for like $24 or less brand new and free shipping.
They are not plug and play though you have to do a little bit of work.