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: [1]   Go Down
  Print  
Author Topic: question: using generator to run power supply  (Read 620 times)
BPONG
Member

Posts: 24




Ignore
« on: February 18, 2010, 07:11:16 AM »

which size of inverter equipped generator is capable of supplying enough AC power to run a jetstream power supply model JTPS28M (25Amp, 12-15V DC) ?
in regards to the AC generator output, the choices are the following:
- 1000 watts, 8 Amps, 120V OR,
- 2000 watts, 15 Amps, 120V

i want to use the power supply to get the required 13.8V for my radio.

i can only estimate that the AC power rating for the power supply is 5 Amps (its fused for 5 Amps) x 110V which would give a power value of 550 watts.  is this a correct calculation ?

i am aware of the possibility of RF interference from the generator but that can be solved by various means as indicated in various posts from the emergency power topic on eham.

any comments that would clarify how to determine the proper size of invertor generator would be greatly appreciated.

thanx in advance, VA3BPO
Logged
AA4PB
Member

Posts: 12899




Ignore
« Reply #1 on: February 18, 2010, 08:57:12 AM »

Correct. The 1000W generator is plenty large enough for that power supply.

Actually you shoud use 120V @ 5A rather than 110V but the supply probably draws less than 5A anyway.

The other way to go about it is to calculate the output power (13.8V x 25A or 345W). Then assuming the supply is 80% efficient multiply 345W x 1.2 to get 414W input.

345W / 120V = 3.45A input current so your 5A calculation provides a little "head room".
Logged
BPONG
Member

Posts: 24




Ignore
« Reply #2 on: February 18, 2010, 09:36:12 AM »

thanx AA4PB for the confirmation.
i wasn't too sure about the numbers.  this is the first time i am using the power equations to determine which generator would fulfill the power requirements.
again, thank you for your reply and have a great arrl field day coming up !!!!
va3bpo
Logged
AA4PB
Member

Posts: 12899




Ignore
« Reply #3 on: February 18, 2010, 11:01:08 AM »

Correction:

414W / 120V = 3.45A input current
Logged
N7NBB
Member

Posts: 380


WWW

Ignore
« Reply #4 on: February 18, 2010, 07:53:23 PM »

I understand your Question was specifically stated to get the power required to run the radio.
HOWEVER you may also at some time or another, want to run some lighting for your station. You may want to use a computer for logging, or perhaps some other accessories  like an automatic tuner, antenna rotator, etc. I'd go for the 2kw generator, if your budget will allow it.  You can (and probably will) find a use for the extra headroom the larger generator will allow... even if it ultimately is not specifically related to Amateur Radio.
Logged
BPONG
Member

Posts: 24




Ignore
« Reply #5 on: February 18, 2010, 08:16:06 PM »

N7NBB, thank you for your remarks about the advantages of having the extra power.  since the differences between the 1000W and 2000W generators are slight (in weight and gas comsumption), it would be a wise decision to chose the 2000W generator.
thank you again, and have a great field day coming up soon !!!!
va3bpo
Logged
W6RMK
Member

Posts: 657




Ignore
« Reply #6 on: February 20, 2010, 02:11:13 PM »

AA4PB wrote:

414W / 120V = 3.45A input current

---

Except you're looking at watts, and that power supply probably doesn't have a unity power factor. While the generator is labeled in "watts"  in reality, it's probably VA.. that is, it has a certain maximum current, regardless of whether that's in phase with the voltage.

If you assume a PF=0.8 (moderately good), the current for your 414 Watt load would be a bit bigger: 3.45/0.8 or 4.3 A. (which is why it has a 5A fuse.. you typically pick a fuse for 1.2 times the load, but also, you'd pick a standard value.. 5A is closer than 10A, which would be the next step).

A bit more than 500VA, so your 1000"Watt" generator (which probably can put out about 8 Amps) is going to be fine.
Logged
Pages: [1]   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!