"Lucky" wrote in message
...

"FDR" wrote in message
...
Check the following link for some info.

http://www.belfuse.com/Data/DBObject/fuseprodguide.pdf

Schurter used to have a nicer guide for fuse selection.

I once had to specify fuse values for an application. The basic premise
is to choose a current value twice that of the maximum steady state. The
other way required measuring in-rush current for the first 10 ms, and
then calculating it from the values.

Fast acting fuses will blow quicker, so you usually have to rate them
higher to avoid nuisance blows.

It's always best to put a fuse after a power supply or source that can
produce high and damaging currents.

"Lucky" wrote in message
...
Hi guys

I have a Icom R75 and Lowe HF-150 I want to run off a Astron PSU model
SL-11a. It's 13.84V and 7Amps. Now, I have some questions please about
how to protect my radios from any mishaps from the PSU or otherwise.

Now the specs for the R75 says it's current drain at 13.80v + or - 15%
is :
Standy 0.9 Amps
Max. Audio 1.1 Amps

I bought a 2 conductor DC accessory cable that has a fuse holder on it.
I will use that to connect the PSU to the radio.
It it means anything it is 22 AWG RS part # 270-025

1] Now, what size fuse should I put in the fuse holder to make sure the
radio is totally protected from the PSU?

2] Am I protecting the radio from too much volts or amps or both? I
figured Amps.

3] I have some 250V 1.6 Amp fast acting fuses. The are 5 x 20mm GMA type
fuses. Radio Shack part number 270-1051. Are these OK? Is the main thing
the Amp rating and not the volt rating?

4] The Icom Radio comes with
3 Amp FGB fuses internally and for the DC cable. Now if the radio draws
say no more then 1.1 Amps, why are they using a 3 amp fuse? Why not 1.5A
or even 2A? Why 3A?

5] So is 1.6A too low, too high, or just good? Should I go even lower to
be sure?

6] Now, the fuse in the Astron PSU itself.
Is that to protect from volt surges or amps surges?

7] Do you think I'm going to extreme measures to protect my receivers
since the Astron PSU is supposed to be that good? I want total peace of
mind knowing I did all I could to protect them.

8] My Lowe HF-150 will use 13.80v and the same PSU also. According to
the manual it can use between 10-15V and it draws approx 300mA but I
think it's more in the 500mA range to work properly.

9] Do you think I need a different fuse size in the holder to protect
the 150 or will what I use to protect the R75 be sufficient for the 150
also?

10] What is the difference between "GMA" and "FGB" type fuses? Is it
better to use the longer ones, the mini ones or it doesn't matter?

I really appreciate the help. The guys at Radio Shack did their best to
help me but they weren't sure.
Thank you
Lucky










Hi FDR,

I think after reading all the suggestions here, I might exchange these
Fast 1.6A's for either 1.8's or 2A if that's the case. Most likely 1.8A.
I'l see.

Thanks
Lucky


By the way, do these fuse holders have a polarity where they need to be
soldered in line properly?
No of course not since you can put the fuse in the holder in either way or
direction. Just figured I ask. I mean if you're not 100% sure but are 99
9/10% sure, why not close the gap on that 1/10th and ask eh?

Lucky

Lucky wrote:


By the way, do these fuse holders have a polarity where they need to be
soldered in line properly?
No of course not since you can put the fuse in the holder in either way or
direction. Just figured I ask. I mean if you're not 100% sure but are 99
9/10% sure, why not close the gap on that 1/10th and ask eh?

Lucky

Not that it matters much, but I generally put the longer side of the fuse holder
on the side that goes to the power supply because you're less likely to have the
contact for the fuse touch something it shouldn't when it's unhooked for
changing.

"Mark S. Holden" wrote in message
...
Lucky wrote:


By the way, do these fuse holders have a polarity where they need to be
soldered in line properly?
No of course not since you can put the fuse in the holder in either way
or
direction. Just figured I ask. I mean if you're not 100% sure but are 99
9/10% sure, why not close the gap on that 1/10th and ask eh?

Lucky

Not that it matters much, but I generally put the longer side of the fuse
holder
on the side that goes to the power supply because you're less likely to
have the
contact for the fuse touch something it shouldn't when it's unhooked for
changing.

Hiya Mark

Yes good thinking. I can see something like that happening after moving,
pulling or repositioning the cables. In fact,I'm going to put a tiny piece
of tape around the holder to seal it.

BTW, should the fuse be as close to the radio or PSU? I was going to put it
close to the PSU since that's where all the dangerous current can originate
from.

1] But now I'm of the understanding I'm really protecting the PSU and it's
environment with this added fuse more then protecting the radio itself,
correct?

2] So if it's the radio that may cause the current failure drain, then the
fuse should be closer to the radio then the PSU correct?

I decided to do all this to protect the radio from the PSU since I'm not
100% sure the PSU doesn't have any defects from perhaps lets say a fall. The
PSU could work perfectly but have a solder joint ready to break.

But I would have done this **anyway. This is my first experience with such a
powerfull power supply that can totally fry
any electrical component conected to it. It kinda intimidates me a little
compared to all the small low powered wall worts I'm used to

I have always put a failsafe in place in most aspects of my life. If I can
fit a level of added security in case the major one fails I'll do it.

Remember it's always better to be SAFE then SORRY.

Always happy to hear from you
Lucky

Lucky wrote:

"Mark S. Holden" wrote in message
...
Lucky wrote:


By the way, do these fuse holders have a polarity where they need to be
soldered in line properly?
No of course not since you can put the fuse in the holder in either way
or
direction. Just figured I ask. I mean if you're not 100% sure but are 99
9/10% sure, why not close the gap on that 1/10th and ask eh?

Lucky

Not that it matters much, but I generally put the longer side of the fuse
holder
on the side that goes to the power supply because you're less likely to
have the
contact for the fuse touch something it shouldn't when it's unhooked for
changing.

Hiya Mark

Yes good thinking. I can see something like that happening after moving,
pulling or repositioning the cables. In fact,I'm going to put a tiny piece
of tape around the holder to seal it.

BTW, should the fuse be as close to the radio or PSU? I was going to put it
close to the PSU since that's where all the dangerous current can originate
from.


That's what I'd do.

1] But now I'm of the understanding I'm really protecting the PSU and it's
environment with this added fuse more then protecting the radio itself,
correct?


Well, if you got a big voltage spike, the fuse might blow before the radio, but
odds are the radio will blow to protect the fuse.

2] So if it's the radio that may cause the current failure drain, then the
fuse should be closer to the radio then the PSU correct?


No. If for example the wires between the PS and the radio got shorted between
the PS and the fuse, the fuse won't blow, and the wires will get nice and hot.

I decided to do all this to protect the radio from the PSU since I'm not
100% sure the PSU doesn't have any defects from perhaps lets say a fall. The
PSU could work perfectly but have a solder joint ready to break.

But I would have done this **anyway. This is my first experience with such a
powerfull power supply that can totally fry
any electrical component conected to it. It kinda intimidates me a little
compared to all the small low powered wall worts I'm used to

I have always put a failsafe in place in most aspects of my life. If I can
fit a level of added security in case the major one fails I'll do it.

Remember it's always better to be SAFE then SORRY.

Always happy to hear from you
Lucky

If you want to protect the radio, your best bet is probably to add some surge
protection - a 15v MOV hooked up on the radio side of the fuse might help blow
the fuse before the radio gets fried.

"Mark S. Holden" wrote in message
...
Lucky wrote:

"Mark S. Holden" wrote in message
...
Lucky wrote:


By the way, do these fuse holders have a polarity where they need to
be
soldered in line properly?
No of course not since you can put the fuse in the holder in either
way
or
direction. Just figured I ask. I mean if you're not 100% sure but are
99
9/10% sure, why not close the gap on that 1/10th and ask eh?

Lucky

Not that it matters much, but I generally put the longer side of the
fuse
holder
on the side that goes to the power supply because you're less likely to
have the
contact for the fuse touch something it shouldn't when it's unhooked
for
changing.

Hiya Mark

Yes good thinking. I can see something like that happening after moving,
pulling or repositioning the cables. In fact,I'm going to put a tiny
piece
of tape around the holder to seal it.

BTW, should the fuse be as close to the radio or PSU? I was going to put
it
close to the PSU since that's where all the dangerous current can
originate
from.


That's what I'd do.

1] But now I'm of the understanding I'm really protecting the PSU and
it's
environment with this added fuse more then protecting the radio itself,
correct?


Well, if you got a big voltage spike, the fuse might blow before the
radio, but
odds are the radio will blow to protect the fuse.

2] So if it's the radio that may cause the current failure drain, then
the
fuse should be closer to the radio then the PSU correct?


No. If for example the wires between the PS and the radio got shorted
between
the PS and the fuse, the fuse won't blow, and the wires will get nice and
hot.

I decided to do all this to protect the radio from the PSU since I'm not
100% sure the PSU doesn't have any defects from perhaps lets say a fall.
The
PSU could work perfectly but have a solder joint ready to break.

But I would have done this **anyway. This is my first experience with
such a
powerfull power supply that can totally fry
any electrical component conected to it. It kinda intimidates me a little
compared to all the small low powered wall worts I'm used to

I have always put a failsafe in place in most aspects of my life. If I
can
fit a level of added security in case the major one fails I'll do it.

Remember it's always better to be SAFE then SORRY.

Always happy to hear from you
Lucky

If you want to protect the radio, your best bet is probably to add some
surge
protection - a 15v MOV hooked up on the radio side of the fuse might help
blow
the fuse before the radio gets fried.

OK Mark,

This MOV [metal oxide varistor}, is it a component I can buy from Radio
Shack and solder in line, or is it an actual physical strip that you plug
the PSU into like a regualr surge protector?

So pick up a 15v MOV and solder it in line before the fuse closer to the
radio and the fuse holder itself closest to the PSU? Right? Wow this is
great help and advise.

Thanks a lot
Lucky

Lucky wrote:

"Mark S. Holden" wrote in message
...
Lucky wrote:

"Mark S. Holden" wrote in message
...
Lucky wrote:


By the way, do these fuse holders have a polarity where they need to
be
soldered in line properly?
No of course not since you can put the fuse in the holder in either
way
or
direction. Just figured I ask. I mean if you're not 100% sure but are
99
9/10% sure, why not close the gap on that 1/10th and ask eh?

Lucky

Not that it matters much, but I generally put the longer side of the
fuse
holder
on the side that goes to the power supply because you're less likely to
have the
contact for the fuse touch something it shouldn't when it's unhooked
for
changing.

Hiya Mark

Yes good thinking. I can see something like that happening after moving,
pulling or repositioning the cables. In fact,I'm going to put a tiny
piece
of tape around the holder to seal it.

BTW, should the fuse be as close to the radio or PSU? I was going to put
it
close to the PSU since that's where all the dangerous current can
originate
from.


That's what I'd do.

1] But now I'm of the understanding I'm really protecting the PSU and
it's
environment with this added fuse more then protecting the radio itself,
correct?


Well, if you got a big voltage spike, the fuse might blow before the
radio, but
odds are the radio will blow to protect the fuse.

2] So if it's the radio that may cause the current failure drain, then
the
fuse should be closer to the radio then the PSU correct?


No. If for example the wires between the PS and the radio got shorted
between
the PS and the fuse, the fuse won't blow, and the wires will get nice and
hot.

I decided to do all this to protect the radio from the PSU since I'm not
100% sure the PSU doesn't have any defects from perhaps lets say a fall.
The
PSU could work perfectly but have a solder joint ready to break.

But I would have done this **anyway. This is my first experience with
such a
powerfull power supply that can totally fry
any electrical component conected to it. It kinda intimidates me a little
compared to all the small low powered wall worts I'm used to

I have always put a failsafe in place in most aspects of my life. If I
can
fit a level of added security in case the major one fails I'll do it.

Remember it's always better to be SAFE then SORRY.

Always happy to hear from you
Lucky

If you want to protect the radio, your best bet is probably to add some
surge
protection - a 15v MOV hooked up on the radio side of the fuse might help
blow
the fuse before the radio gets fried.

OK Mark,

This MOV [metal oxide varistor}, is it a component I can buy from Radio
Shack and solder in line, or is it an actual physical strip that you plug
the PSU into like a regualr surge protector?

So pick up a 15v MOV and solder it in line before the fuse closer to the
radio and the fuse holder itself closest to the PSU? Right? Wow this is
great help and advise.

Thanks a lot
Lucky

I doubt you'll find a 15v MOV at radio shack unless it's in a special order
catalog.

It would get hooked in after the fuse, and before the radio. The hope is the
current draw from the MOV clamping down on the voltage spike will help blow the
fuse before your radio gets fried.

I don't think this will protect your radio from a serious spike, but you're not
likely to spend more than a few bucks for a mov, so what the heck.

"Mark S. Holden" wrote in message
...
Lucky wrote:

"Mark S. Holden" wrote in message
...
Lucky wrote:

"Mark S. Holden" wrote in message
...
Lucky wrote:


By the way, do these fuse holders have a polarity where they need
to
be
soldered in line properly?
No of course not since you can put the fuse in the holder in either
way
or
direction. Just figured I ask. I mean if you're not 100% sure but
are
99
9/10% sure, why not close the gap on that 1/10th and ask eh?

Lucky

Not that it matters much, but I generally put the longer side of the
fuse
holder
on the side that goes to the power supply because you're less likely
to
have the
contact for the fuse touch something it shouldn't when it's unhooked
for
changing.

Hiya Mark

Yes good thinking. I can see something like that happening after
moving,
pulling or repositioning the cables. In fact,I'm going to put a tiny
piece
of tape around the holder to seal it.

BTW, should the fuse be as close to the radio or PSU? I was going to
put
it
close to the PSU since that's where all the dangerous current can
originate
from.


That's what I'd do.

1] But now I'm of the understanding I'm really protecting the PSU and
it's
environment with this added fuse more then protecting the radio
itself,
correct?


Well, if you got a big voltage spike, the fuse might blow before the
radio, but
odds are the radio will blow to protect the fuse.

2] So if it's the radio that may cause the current failure drain, then
the
fuse should be closer to the radio then the PSU correct?


No. If for example the wires between the PS and the radio got shorted
between
the PS and the fuse, the fuse won't blow, and the wires will get nice
and
hot.

I decided to do all this to protect the radio from the PSU since I'm
not
100% sure the PSU doesn't have any defects from perhaps lets say a
fall.
The
PSU could work perfectly but have a solder joint ready to break.

But I would have done this **anyway. This is my first experience with
such a
powerfull power supply that can totally fry
any electrical component conected to it. It kinda intimidates me a
little
compared to all the small low powered wall worts I'm used to

I have always put a failsafe in place in most aspects of my life. If I
can
fit a level of added security in case the major one fails I'll do it.

Remember it's always better to be SAFE then SORRY.

Always happy to hear from you
Lucky

If you want to protect the radio, your best bet is probably to add some
surge
protection - a 15v MOV hooked up on the radio side of the fuse might
help
blow
the fuse before the radio gets fried.

OK Mark,

This MOV [metal oxide varistor}, is it a component I can buy from Radio
Shack and solder in line, or is it an actual physical strip that you plug
the PSU into like a regualr surge protector?

So pick up a 15v MOV and solder it in line before the fuse closer to the
radio and the fuse holder itself closest to the PSU? Right? Wow this is
great help and advise.

Thanks a lot
Lucky

I doubt you'll find a 15v MOV at radio shack unless it's in a special
order
catalog.

It would get hooked in after the fuse, and before the radio. The hope is
the
current draw from the MOV clamping down on the voltage spike will help
blow the
fuse before your radio gets fried.

I don't think this will protect your radio from a serious spike, but
you're not
likely to spend more than a few bucks for a mov, so what the heck.

Mark,

Ratso Shackups only shows 1 MOV. Here is the product and 2nd link is the
specs.

http://www.radioshack.com/product.as...t%5Fid=276-568

specs:
http://support.radioshack.com/suppor...oc38/38010.htm

Lucky