The stereo channels in stereo radios (or at least in some stereo radios)
must have a feedbacl/load on them or otherwise one or the other channels
can blow/malfunction/stop working.I once read an article about that in a
magazine.I am not an expert on things like that,perhaps it depends on
the quality or how a stereo radio is designed.But I do know of one
instance of it happened to the first sound amplifier I bought at a Radio
Shack store and I am pretty sure that is what caused the problem with
the stereo AM/FM radio in his car.
cuhulin

Stereo amps run fine without a load. I suppose there could be a poorly
engineered stereo with gain in the output stage that would be unstable
without a load, but that wouldn't cause it to blow up.

There are a few electronic items that can be blown if not loaded. Some
RF amplifiers can't handle the no-load condition, but most modern gear
is engineered to handle no load and shorts. Some poorly engineered
Dc/Dc converters can't handle the no-load condition.

wrote:
The stereo channels in stereo radios (or at least in some stereo radios)
must have a feedbacl/load on them or otherwise one or the other channels
can blow/malfunction/stop working.I once read an article about that in a
magazine.I am not an expert on things like that,perhaps it depends on
the quality or how a stereo radio is designed.But I do know of one
instance of it happened to the first sound amplifier I bought at a Radio
Shack store and I am pretty sure that is what caused the problem with
the stereo AM/FM radio in his car.
cuhulin

In article .com,
wrote:

Stereo amps run fine without a load. I suppose there could be a poorly
engineered stereo with gain in the output stage that would be unstable
without a load, but that wouldn't cause it to blow up.

There are a few electronic items that can be blown if not loaded. Some
RF amplifiers can't handle the no-load condition, but most modern gear
is engineered to handle no load and shorts. Some poorly engineered
Dc/Dc converters can't handle the no-load condition.

Snip

That's because an load open just like a short load causes the RF
amplifier output to dissipate two times the output power. Opens and
shorts both cause 100% power reflections. On older generation equipment
operating into an open or short usually meant the output would be blown.
Equipment built these days have more power handling margin on the small
signal stuff. Usually the higher you go in frequency capability the less
likely an amplifier will withstand a 100% reflection. Big amplifiers
will still get destroyed at any frequency. High power TWT's can be
ruined in a few seconds. The prior comments refer to utility amplifiers.
Commercial ham gear these days have power fold-back protection that
usually but not always saves the finals.

--
Telamon
Ventura, California

Basically the energy is being reflected back to the RF amp instead of
going to the load.

When DxAss was a long haired hippie back in the 60's, he used to break
the antenna off police cruisers. When the cop hit the PTT, the radio
would fry.


Telamon wrote:
In article .com,
wrote:

Stereo amps run fine without a load. I suppose there could be a poorly
engineered stereo with gain in the output stage that would be unstable
without a load, but that wouldn't cause it to blow up.

There are a few electronic items that can be blown if not loaded. Some
RF amplifiers can't handle the no-load condition, but most modern gear
is engineered to handle no load and shorts. Some poorly engineered
Dc/Dc converters can't handle the no-load condition.

Snip

That's because an load open just like a short load causes the RF
amplifier output to dissipate two times the output power. Opens and
shorts both cause 100% power reflections. On older generation equipment
operating into an open or short usually meant the output would be blown.
Equipment built these days have more power handling margin on the small
signal stuff. Usually the higher you go in frequency capability the less
likely an amplifier will withstand a 100% reflection. Big amplifiers
will still get destroyed at any frequency. High power TWT's can be
ruined in a few seconds. The prior comments refer to utility amplifiers.
Commercial ham gear these days have power fold-back protection that
usually but not always saves the finals.

--
Telamon
Ventura, California

Thanks for explaining that,Telamon.y'all know I am not too techified on
explaining some techy things.But I do sort of kind of know what I am/was
tallking about.Hey,send us some of that warm California weather over
there to here in beautifull Jackson,Mississippi,,,, my po old feets is
freezing.
cuhulin

In article
,
Telamon wrote:

In article .com,
wrote:

Stereo amps run fine without a load. I suppose there could be a poorly
engineered stereo with gain in the output stage that would be unstable
without a load, but that wouldn't cause it to blow up.

There are a few electronic items that can be blown if not loaded. Some
RF amplifiers can't handle the no-load condition, but most modern gear
is engineered to handle no load and shorts. Some poorly engineered
Dc/Dc converters can't handle the no-load condition.

Snip

That's because an load open just like a short load causes the RF
amplifier output to dissipate two times the output power. Opens and
shorts both cause 100% power reflections. On older generation equipment
operating into an open or short usually meant the output would be blown.
Equipment built these days have more power handling margin on the small
signal stuff. Usually the higher you go in frequency capability the less
likely an amplifier will withstand a 100% reflection. Big amplifiers
will still get destroyed at any frequency. High power TWT's can be
ruined in a few seconds. The prior comments refer to utility amplifiers.
Commercial ham gear these days have power fold-back protection that
usually but not always saves the finals.

I see you also referred to DC to DC converters. Those devices along with
many industrial power supplies have minimum load requirements for the
control feedback circuits to operate within specifications. Without the
minimum loads the gain/phase of the control circuitry can go into a
positive feedback mode when they are supposed to be in a negative
feedback mode so yeah they can even blow up for that reason, which is a
completely different reason from the RF amplifiers explanation.

--
Telamon
Ventura, California

wrote:
Stereo amps run fine without a load. I suppose there could be a poorly
engineered stereo with gain in the output stage that would be unstable
without a load, but that wouldn't cause it to blow up.

There are a few electronic items that can be blown if not loaded. Some
RF amplifiers can't handle the no-load condition, but most modern gear
is engineered to handle no load and shorts. Some poorly engineered
Dc/Dc converters can't handle the no-load condition.

--------------------------
It might be safer or better to say that transformerless
amplifiers(OTL), either
stereo or mono power amplifiers can almost always operate safely
without a load.
I remember a Kakimichi ~50W unit that tended to go into ultrasonic
oscillation
unless it was operated with something close to 8 ohms.

However transformer output amps will more freqeuntly then not self
destruct
with any significant power. Tubes survive slighlty longer then
transisitors.
Transistors will very frequcnly "pop" on the first load sound impulse
where
tubes may survive the high voltage spike only to have the output
tranformer
arc through in short order. I have made nice money repairing older
Macintosh,
audio not PC, amplifiers that people had neglected to operate under
load.

And I made a nice bundle repairing a high power Marshall guitar amp
that
a doper guitarist fried by operating with the speakers disconnected.
this
unit operated with about 1400V DC on the plate. Most of us will not see

consumer power audio, and damn little pro, gear that has output
transformers.

I no longer do much work on tubed gear because in a +12V world I fear I
might
have becmoe a bit lax in my safety habbits.

Touching, while also touching ground, a 1400 plate line will KILL you!
A good tech I new screwed up back in 1985, he got just a little
careless
on a Marshal amplifier "head" and got bit but good.

Terry

I rarely ever use earbuds or earphones because I just dont like to wear
them at all,my eyeglasses give me problems enough rubbing around on my
nose and making it hurt.Even so,on the rare occasions when I do use
earbuds and if whatever device I am using with them,radio,my sound
amplifier gadget,cassette recorder/player,whatever,I never let the
earbuds get too close together.
cuhulin