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Author Topic: Astron Power Supply efficiency  (Read 16871 times)
W8JX
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« on: February 16, 2011, 07:44:50 AM »

I just did a test that many may find interesting especially those wanting to be more "green". Using a old style Astron 20amp Linear supply and a Astron 30 amp switching supply I made the following observations.  Also the test rig was a Kenwood TS-570 and transmitting FSK into a dummy load.  Furthermore radio draws 1.45 amp on standby and 12.46 amps at 50 watts out and 17.4 amps at 100 watts out @13.8 volts.

RS20

Turned on no load:                             18 watts   total
With radio turned on low volume:        53 watts   total
With radio transmitting 50 watts:        310 watts  total
With radio transmitting 100 watts:      436 watts  total


In summary, power supply draws 35 watts extra to power radio and 292 watts extra to transmit 50 watts and 418 watts extra at 100 watts output


SS30

Turned on no load:                              9 watts   total
With radio turned on low volume:        36 watts   total
With radio transmitting:                     215 watts  total
With radio transmitting 100 watts:      306 watts  total

In summary, power supply draws 27 watts extra to power radio and 206 watts extra to transmit 50 watts and 297 watts extra for 100 watts out


Overall efficiency we see that RS20 is  37% at standby and  55% @ 50 watts and  55% @100 watts key down

And for the SS30 it is  55% at standby and  80% @50 watts and 79% @100 watts at key down

It has gotten my attention and I am retiring RS20a to standby duty. A even bigger linear supply would likely have even greater efficiency losses at light to moderate loads. The RS20 uses more power from wall socket at 50 watts out than SS30 does at 100 watts out. Very good reason to go with a switching supply here.   Smiley
« Last Edit: February 16, 2011, 08:27:01 AM by W8JX » Logged

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WB2WIK
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« Reply #1 on: February 16, 2011, 10:57:14 AM »

Good observations; seems about right...however how did you measure the line power consumed (AC)?

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W8JX
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« Reply #2 on: February 16, 2011, 06:39:03 PM »

Those readings were as taken at socket plug for power supply. (it was plugged into a device that measure power being used) Line voltage was 120.1 during test. I was kinda surprised at the difference. 
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WX7G
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« Reply #3 on: February 17, 2011, 02:17:53 AM »

Good data. Most rigs spend most of their time in receive mode. With the 17 watt difference and figuring 7 cents per kW-hr the payback for switching to the $140 SS30 occurs after 13 years of continous use.
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W8JX
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« Reply #4 on: February 17, 2011, 12:18:33 PM »

Also consider that the linear supply I used was a RS-20 and many use a RS-35 which surely would have a higher usage idle no load and also therefore power efficiency on light loads too. In this case the saving with a SS30 would be greater. I have no RS35 here to test.  I do have a Astron SL-11 and it draws only 7 watts on standby with no load.
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W3LK
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« Reply #5 on: February 17, 2011, 02:07:13 PM »

Good data. Most rigs spend most of their time in receive mode. With the 17 watt difference and figuring 7 cents per kW-hr the payback for switching to the $140 SS30 occurs after 13 years of continous use.

While the data is interesting, the difference is not enough to make me replace my existing Astrons.

I was reading a story about the new crop of computerized front-loading washing machines. They cost anywhere from 70 to 100 percent more than a comparable top loader and the dollar savings in water and electricity average $48/year. Considering the average life of a washing machine in 7-10 years. one will be hard pressed to recover the increased cost within the lifespan of the unit. Not to mention that repairs run 75 to 300 percent higher than a top loader.

Same deal with power supplies - linear supplies are generally easily repaired by the average ham and switchers seem to not be.
« Last Edit: February 17, 2011, 02:08:44 PM by W3LK » Logged

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W8JX
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« Reply #6 on: February 17, 2011, 03:32:09 PM »

Switchers are here to stay and very reliable if properly sized for load. Linear power supplies are going the way of incandescent bulb which are very inefficient too. I was a believer in old technology power supplies until and saw how inefficient they are.
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W3LK
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« Reply #7 on: February 17, 2011, 03:47:06 PM »

Switchers are here to stay and very reliable if properly sized for load. Linear power supplies are going the way of incandescent bulb which are very inefficient too. I was a believer in old technology power supplies until and saw how inefficient they are.

No argument, but I see no need to replace perfectly functioning equipment until it dies, especially since any actual savings in the interim is minimal, at best.

If you get the idea that I'm not exactly a big fan of being "green", you are very astute. Smiley

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W8JX
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« Reply #8 on: February 17, 2011, 04:03:05 PM »

Well for me it is not about being green per say but rather more efficient when possible. Maybe I might save 20 or 30 bucks a year which will not break the bank but point is it is money to spend elsewhere. Also when it comes to emergency power, my shack can run off two each 1 KW UPS and one is commercial duty with external batteries and the switch puts far less load on even at 100 watts out and no power supply start-up surge either.    Also during cooling season there is less heat to cool too.
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W3LK
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« Reply #9 on: February 17, 2011, 05:41:01 PM »

To each his own ... for whatever reason(s).
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KE3WD
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« Reply #10 on: February 17, 2011, 05:43:37 PM »

And many of the more modern switcher designs also include Power Factor Correction, as well.  


With a very wide AC voltage input range.  

Coupled with the genset, it is indeed a win-win situation for the EMCOMM operator or even the casual portable or camper operation as well as the contester, who these days may be able to garner some extras as contests follow Field Day on the idea of including these kind of off the grid power sources.  

Smaller size, MUCH lighter in weight, the tradeoff is heightened complexity and possibly lower MTBF due to the component count.  

Troubleshooting and repairing switchers is not the impossible task that the uninitiated like to speak about, either.  We have to get over the ridiculous notion that "change = bad" someday.  

It is a good thing to have choices. 

It is an even better thing to be able to make those choices by design. 


73
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WB2WIK
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« Reply #11 on: February 18, 2011, 01:42:58 PM »

And many of the more modern switcher designs also include Power Factor Correction, as well.  


With a very wide AC voltage input range.

Indeed.  Actually to comply with CE requirements in Europe, power supplies above 70W (I think) must be power factor corrected.  And it's very true that many, and probably most, switch mode power supplies are "universal input," 90-264Vrms 50/60 Hz, so if you change countries you only need change a plug (adapter) and nothing else.  Very handy! 

 
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W3LK
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« Reply #12 on: February 18, 2011, 03:22:36 PM »

I guess I didn't phrase my replies correctly, so let me try again.

(1) I have nothing against switcher power supplies. I have a Samlex that I use with my drag-along-rig, but I have two linear Astrons in the shack, plus a spare.
(2) The projected savings in electricity is measurable, but not considerable, and it will take more than a few years of continuous service to recover the additional cost vs a linear.
(3) In light of (2), I see no need to replace perfectly functioning power supplies at this time. When one fails, possibly, maybe even probably, but not until then.
(4) I am not against change, but not just for change's sake; I have to have a reason, and personally, the minuscule savings over the course of a year isn't a sufficient enough reason.

As I posted previously, To each his own ... for whatever reason(s).
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KE3WD
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« Reply #13 on: February 18, 2011, 04:14:40 PM »

Aw c'mon, Lou, you know me well enough by now to know that penny pinchin' yours truly wouldn't toss *any* working piece of anything unless and until it is of no value of any kind.  And even then, I usually strip out whatever is left that may be good, or at least save the case and chassis for a future project. 

I'm also well known for buying a new car and hanging on to it until I have driven it into. the. ground.  *grin*


73
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W8JX
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« Reply #14 on: February 18, 2011, 08:14:12 PM »


I'm also well known for buying a new car and hanging on to it until I have driven it into. the. ground.  *grin*


I tend to keep them at least 8 to 10 years and usually 200k miles or more too
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