Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: Prev 1 [2] 3 Next   Go Down
  Print  
Author Topic: Power Supply size?  (Read 4359 times)
W8JX
Member

Posts: 6476




Ignore
« Reply #15 on: February 17, 2013, 03:18:36 PM »

25A with 30-35 amp surge will be more than enough. I know people that have used Astron 20A with no problem

An Astron RS20A is rated for 20A intermittent and only 16A continuous. Thats not good for a radio that is specified at 22A key down plus the addition of some other accessories.


It is rated at 20 amps at a 50% duty cycle. It will actually do more as it does not cut off at 20 amps. As I have side before, I used one nearly 15 years before replacing it with a SS30. Even had a VHF/UHF mobile on at same time a lot but only actually transmitted on one at a time.  Again I have never tested a HF rig that actually drew what it was rated at. It was always less.
« Last Edit: February 17, 2013, 03:28:45 PM by W8JX » Logged

--------------------------------------
All posted wireless using Win 8.1 RT, a Android tablet using 4G/LTE/WiFi or Sprint Note 3.
N4NYY
Member

Posts: 4818




Ignore
« Reply #16 on: February 17, 2013, 03:19:10 PM »

25A with 30-35 amp surge will be more than enough. I know people that have used Astron 20A with no problem

An Astron RS20A is rated for 20A intermittent and only 16A continuous. Thats not good for a radio that is specified at 22A key down plus the addition of some other accessories.


I have a RS-35m. I said I know people that use a 20 amp Astron.  I suggested 25A continuous.
Logged
N8NSN
Member

Posts: 283


WWW

Ignore
« Reply #17 on: February 17, 2013, 04:17:19 PM »

Many good replies.

One easy way to make any piece in a station last (provided no accidental damages happen):

Leave head room.

It's been the typical experience that most gear lasts much longer if not pushed to it's specified limits of operation on a regular basis.

The last place you want to experience a failure in em comm equipment is in the field.

I agree a 35 amp PS is the best answer.
Answer #1A as a subpart to the 35 Amp answer is transient voltage protection. Furman makes some nice 1/2 rack width and full 19 & 1/4 inch standard width - line conditioners. Some of them are pr icy, but a conditioner that can take 84<145 VAC and keep her steady at 115 VAC has some "meat" to it. Could easily be considered money well spent if it runs the go-box for many years and/or "gets the job done" when under critical demand.
Logged
KE3WD
Member

Posts: 5689




Ignore
« Reply #18 on: February 17, 2013, 05:21:08 PM »

The term for specifying a power supply that can deliver higher amperage than needed is: 

Derate 


Derating a power supply *by a reasonable amount* is always a good thing for the power supply's MTBF. 


73
Logged
AA4PB
Member

Posts: 12990




Ignore
« Reply #19 on: February 17, 2013, 05:51:25 PM »

Well, if a power supply is rated at 20A peak then the current limiter will probably fold back if you exceed 20A, even momentarily. If his radio really draws 22A on voice peaks then the supply voltage will drop every time he hits a voice peak. He's likely to have a distorted SSB signal unless he keeps the audio drive level low.

Much better to purchase a little larger power supply IMHO.
Logged
W8JX
Member

Posts: 6476




Ignore
« Reply #20 on: February 17, 2013, 09:08:14 PM »

Well, if a power supply is rated at 20A peak then the current limiter will probably fold back if you exceed 20A, even momentarily. If his radio really draws 22A on voice peaks then the supply voltage will drop every time he hits a voice peak. He's likely to have a distorted SSB signal unless he keeps the audio drive level low.

Much better to purchase a little larger power supply IMHO.


A RS 20 is rated at 20 amps @ 50% duty cycle not 20 amps peak. Most HF modes are far less than 50% too at full draw too. I NEVER had any problems with mine and again never saw a rig that draws its rated amount either when checked. It is always less. Bigger is not always needed nor is it always better either.
« Last Edit: February 17, 2013, 09:50:54 PM by W8JX » Logged

--------------------------------------
All posted wireless using Win 8.1 RT, a Android tablet using 4G/LTE/WiFi or Sprint Note 3.
AF5C
Member

Posts: 123




Ignore
« Reply #21 on: February 17, 2013, 09:28:38 PM »

According to the QST review, the 857 draws 16A at full output.

John AF5CC
Logged
W5LZ
Member

Posts: 477




Ignore
« Reply #22 on: February 17, 2013, 10:03:43 PM »

I'm not going to argue about how much current a particular radio draws.  I will say that having a larger than needed power supply always comes in handy.  Tell me you never added some little do-dad to that power supply later, or never wished the @#$ thing was just a little bit bigger so that you could power something else from it too.  How much is 'too much' is something you will have to decide though.
 -Paul
Logged
W8JX
Member

Posts: 6476




Ignore
« Reply #23 on: February 18, 2013, 08:39:54 AM »

I'm not going to argue about how much current a particular radio draws.  I will say that having a larger than needed power supply always comes in handy.  Tell me you never added some little do-dad to that power supply later, or never wished the @#$ thing was just a little bit bigger so that you could power something else from it too.  How much is 'too much' is something you will have to decide though.
 -Paul


With that logic better buy a 1 ton pickup and trailer too as you might need to haul something one day too.
Logged

--------------------------------------
All posted wireless using Win 8.1 RT, a Android tablet using 4G/LTE/WiFi or Sprint Note 3.
WH7DX
Member

Posts: 1029




Ignore
« Reply #24 on: February 18, 2013, 02:16:04 PM »

Get the astron rs 35m.    It's 25a continuous and 35a peak.   It's only $40 extra for the higher power.    With cw and 100w the lights still dim but it's fine.   

I wouldn't go less than 25a continuous. 
Logged
KE3WD
Member

Posts: 5689




Ignore
« Reply #25 on: February 18, 2013, 04:00:09 PM »

A 35m for use in an EmComm Go Kit.


right. 


Um, would the wheelbarrow be optional?



Logged
AC5UP
Member

Posts: 3928




Ignore
« Reply #26 on: February 18, 2013, 04:41:39 PM »


We should cut N4NYY some slack. He's been working on a job application all weekend.

Dude is interested in a position that opened up late last week at the Vatican.

 Tongue
Logged

Never change a password on a Friday                
WH7DX
Member

Posts: 1029




Ignore
« Reply #27 on: February 18, 2013, 05:08:46 PM »

Use the 35m for home and a small car battery for portable... Either on the car or extra.

True portable would be the internal 897 which I own as a potable second radio and also hooked up to my 600ft beverage.   

Get a small solar kit to charge battery or just run the vehicle with jumpers.
Logged
WH7DX
Member

Posts: 1029




Ignore
« Reply #28 on: February 18, 2013, 05:42:04 PM »

Here you go. 

This is a portable 857 with small battery..   Will need to trade off battery size and weight for output watts etc....

I wired my 897 with connectors and fuse already on the radio and on the Astron RS-35M power supply at the house with connectors on that side and with an extra set for a battery. 

All I need to do is pull the connectors apart on the home power, put the battery connectors on and plug the radio in.  I figured I'd always have a battery and didn't want to spend the money for the Internal battery for the 897.

My 35M also connects to the Kenwood TS-570, Diawa Meter and FTL Meter.  There is also something to add

http://www.youtube.com/watch?v=jLSzSeajr7U

Logged
N4NYY
Member

Posts: 4818




Ignore
« Reply #29 on: February 18, 2013, 06:37:57 PM »

A 35m for use in an EmComm Go Kit.


right. 


Um, would the wheelbarrow be optional?





I have a 35M. I did not suggest that. I suggested a 25 amp continuous. There are a ton of those switchers around for portable operation, which is why I did not specify a brand. Why do you have to be condescending?
Logged
Pages: Prev 1 [2] 3 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!