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Sofkow
| | Posted on Thursday, February 20, 2003 - 1:27 am: | 
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question...
I'm running a shooting star 200 on a 25 amp power supply. now, common sense tells me that when i'm running on "high", the meter on the power supply should show that it's putting out around 20 or so amps. It doesn't. On "low" it's pegging at 9, "med" at 10, and "high", at around 11. shouldn't I be pushing more amps through the power supply? It seems to be running fine at these readings. |
Znut
| | Posted on Thursday, February 20, 2003 - 10:16 am: |
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My shooting star 225 does similar. |
307
| | Posted on Thursday, February 20, 2003 - 6:59 pm: |
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Shooting Star 200 is a 100 watts. If the efficiency was 100% which is not , it would draw a max of...100/13.8 = 7.2 amps. 11 to 12 amps is correct at 60% or so EFF... |
Ss8541
| | Posted on Friday, February 21, 2003 - 12:17 am: |
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one question here before i go into peak and average reading amperage meters(all power supply meters are average), what is the difference between the s.star 200 and the s.star 225? i have seen many 'shooting stars'(that is the only description on the face-no numerical markings) so i don't know if they all were 225's, 200's or a mix.
getting to your post, it is impossible to give a solid answer to your question without knowing if you are talking about am or ssb mode. the meter will not read peak current draw in am(with modulation applied) because it is an average reading meter. it will read peak current draw in ssb with a single tone(such as a whistle). whatever you get for max c. draw in ssb, the am max current draw will be very close(regardless of what meter shows). as an example of how power supply meters do not show peak current draw, if you have a radio and amp combo that has perfect 100% +/- modulation, the carrier current and modulated current will be the same. the reason is that the + and - current(modulation) peaks cancel each other out leaving only the carrier current draw.
any way, once again, can anyone tell me the difference between the 200 and the 225? all the 'shooting stars' that i have seen will produce a clean and linear 140-160wpep with a max output around 200wpep. |
307
| | Posted on Friday, February 21, 2003 - 7:15 am: |
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I just pulled out a new Shooting Star 200 and hooked it up to an Astron RS-70M power supply. With 4 watt drive (dead key)the output was exactly 110 watts and the current draw was 11 amps an AM. On SSB with 12 watts max drive the current meter shows 13 amps. I hope this helps Ss8541. |
Sofkow
| | Posted on Friday, February 21, 2003 - 3:02 pm: |
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thank you, 307. |
Ss8541
| | Posted on Saturday, February 22, 2003 - 12:19 am: |
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sorry 307, but that doens't tell me much about any differences. from what you described that amp sounds like the 'shooting star' using the 1446 trans that everyone calls the 'shooting star 225' even though there are no numerical markings on the face.
and i was not disagreeing with what you said since i have not seen the 'shooting star 200'(if it is any different from the 'shooting star'). but it -was- impossible to give a solid answer without knowing if he was talking about ssb, am with carrier only, or am with modulation. you get different readings with all three. the answer you gave was for 100w of ssb single tone pep/100w am carrier. 100w of carrier for the 200 or the 225(regardless of any differences that may exist) will give backward amperage swing when modulation is applied since the carrier is way too high. so now you would have even a different reading. this is why i wrote about peak and average reading amperage meters. you have to know how the meters in power supplies work to know what to look for with different forms of modulation. if it doesn't help sofkow, it will help someone else who is also electronically inclined and intuitive.
what i was wanting to know is what is the difference internally, externally, etc between the 225 and the 200? does the 'shooting star 200' say 200 on the outside or is it just marked 'shooting star'? i guess what i am asking is; is there any chance that there is one 'shooting star' going by two names; 225 and 200??
here is a rule of thumb for anyone wanting to know peak current draw of an amp used in am with modulation applied. this only applies to amps that are capable of hitting atleast 100% positive modulation. as an example, a 'shooting star 225 or 200' with 100w of carrier isn't close to making 100% positive modulation, at a 25w carrier it would be. multiply displayed amperage by 1.33. this will give you a close figure of what the peak current draw is with modulation. |
Ss8541
| | Posted on Saturday, February 22, 2003 - 9:30 am: |
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the post above is incorrect. i worked 13hrs yesterday before i made that post, by the time a i posted at midnight last night, i was a zombie.
the 1.33 is for dosy/astatic type -wattmeters-. for power supplies the amperage should be multiplied by 2(not 1.33) to get peak current draw with modulation. but once again amp must also be able to hit 100% positive modulation for this to work(which means about 1.5-2w carrier input for 85% of the amps out there). so an amp that is -showing- 11amps of current when modulation like a whistle or single tone is used, it is actually hitting 22amps at it modulation peaks. |
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