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can a amp be underdriven ?

B

BOOTY MONSTER

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i know a amp has to have the correct ammount of voltage and amperage to work properly . but , can a amp be dammaged by too little power if its getting enough to key up properly ? i was told on another forum that it would dammage the amp eventually .

as an extreme example....according to a page at jacks ( http://www.firecommunications.com/dx1600.txt ) site on a texas star sweet 16 , a 4 watt deadkey in will give a 175 watt deadkey out and 20 watts in will give 700 out . i know the amp has the ability to do a lot more clean power than that , but would it hurt it running a barefoot tuned radio with it ? was i told correctly and just too bone headed to believe it till one of the brains here tell me the same thing ? lol
 

Rats! Guess I didn't wait long enough for the 'first' post to show up. Oh well, wasn't worth looking at anyway, who cares about thermal expansion differences.
- 'Doc
 
Second try at posting. Considering how long the 'other' one was, not getting it on the forum probably isn't a 'bad' thing.

Can an amplifier be underdriven? Sure. Will it harm the amplifier? I seriously doubt it. Like QRN, I've never heard of an amplifier being hurt from too little drive. So what happens? Basically, the output power gets smaller until there isn't enough drive to even 'tickle' the amplifying devices, then there's no output from the amplifier. Sort of like hooking a 'AAA' battery to a 100watt light bulb...
- 'Doc
 
Booty has been reading the same things I have...and I finally said to myself "if it doesn't have enough drive, it won't key the relay".

I believe Booty is speaking of transistor-type amplifiers...
 
yep steved im talking about transistor amps thats why i used the texas star 1600 as an example . so basically if it keys up on am then its ok even though the amp isnt being used to its full potiental .
thanks guys ;)
 
Solidstate amps or tube amps,the same thing applies. As long as there is enough drive to trigger the switching relay ,if the amp has one, then things will be fine. As I said, the efficiency may be a bit lower than normal but the signal will be much cleaner than if you drove the crap out of it.
 
I guess what would be the next logical question would be...what is considered under driven?

Are we talking a couple percent of rated input, or half of the rated input??? And I'm not being smart here, just trying to get a "quantitative" answer on a "qualitative" statement.

Wouldn't we be more concerned about the cleanliness of the input?
 
you reading my mind now steve !!! those would have been my next questions.......but without the big words . ;)
 
steved said:
Booty has been reading the same things I have...and I finally said to myself "if it doesn't have enough drive, it won't key the relay".

I believe Booty is speaking of transistor-type amplifiers...
Click to expand...

Well the relay can be made to key at extremely low input, say 1/4 watt but at that it still might not be enough to turn on the output transistors depending on what turns ratio is involved on the input of the amp.
 
ss8541 said:
actually, underdriving an amp can cause damage. underdrive can cause the amp to break into parasitic oscillations that can destroy the transistors.
Click to expand...

Actually Richard,you bring up a good point that I had not thought about. After reading your post I got to looking at some info I have and you are correct. I stand corrected on this. When driven at very low levels it is possibe for the amp to become unstable and generate parasitic oscillations and damage the tubes/transistors.I was only thinking about grid drive levels and dissapation ratings as well as changeover switching.
 
QRN said:
Actually Richard,you bring up a good point that I had not thought about. After reading your post I got to looking at some info I have and you are correct. I stand corrected on this. When driven at very low levels it is possibe for the amp to become unstable and generate parasitic oscillations and damage the tubes/transistors.I was only thinking about grid drive levels and dissapation ratings as well as changeover switching.
Click to expand...



Any idea of the level?
 
so just for example...... . since the 1600 will do 175 watts with a 4 watt dead key , will or can a 4 watt dead key cause the parasitic oscillations youre talking about ?
 

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