isolation transformer
 

Hello,

Can I use one of those cheap ol' Walmart power strips to as an isolation
transfomer (I need to work on my TS-940), or will I need to get a real
isolation transformer to prevent a ground loop.

The reason I ask, is that about 15 years ago while in tech school, one of my
buddies was working on a TV (NOT plugged in to an isolation transformer)
using an OScope (NOT plugged it to an isolation transformer, either), and
boy was he really suprised when that probe scratched against the chassis on
the tv set.

73's
Ken
KD5ZCL

if you are servicing hot-chassis equipment, It Is INCUMBENT that you
power it through an isolation transformer to avoid becoming worm bait.
nothing else is safe.

the other way to say that is you don't use one, you die and/or burn the
place down and also kill the gear you're working on.

I got a nice 500-watter from a surplus outfit for $40 a couple months
ago. forget the name of the joint, something like skyline surplus just
outside cape canaveral. google for it, or do a search on slashdot,
which is where I got twigged to it.

you will also find this is an item that surplus stores can't keep in
stock, so they keep making deals and offering them. there is no good
reason except having way more money than you can bear to spend several
hundred dollars for one with a test-equipment company name on it.

Ken Luther wrote:

Hello,

Can I use one of those cheap ol' Walmart power strips to as an isolation
transfomer (I need to work on my TS-940), or will I need to get a real
isolation transformer to prevent a ground loop.

The reason I ask, is that about 15 years ago while in tech school, one of my
buddies was working on a TV (NOT plugged in to an isolation transformer)
using an OScope (NOT plugged it to an isolation transformer, either), and
boy was he really suprised when that probe scratched against the chassis on
the tv set.

73's
Ken
KD5ZCL

-- If it's a "new economy," why do they want my obsolete old money?

if you are servicing hot-chassis equipment, It Is INCUMBENT that you
power it through an isolation transformer to avoid becoming worm bait.
nothing else is safe.

the other way to say that is you don't use one, you die and/or burn the
place down and also kill the gear you're working on.

I got a nice 500-watter from a surplus outfit for $40 a couple months
ago. forget the name of the joint, something like skyline surplus just
outside cape canaveral. google for it, or do a search on slashdot,
which is where I got twigged to it.

you will also find this is an item that surplus stores can't keep in
stock, so they keep making deals and offering them. there is no good
reason except having way more money than you can bear to spend several
hundred dollars for one with a test-equipment company name on it.

Ken Luther wrote:

Hello,

Can I use one of those cheap ol' Walmart power strips to as an isolation
transfomer (I need to work on my TS-940), or will I need to get a real
isolation transformer to prevent a ground loop.

The reason I ask, is that about 15 years ago while in tech school, one of my
buddies was working on a TV (NOT plugged in to an isolation transformer)
using an OScope (NOT plugged it to an isolation transformer, either), and
boy was he really suprised when that probe scratched against the chassis on
the tv set.

73's
Ken
KD5ZCL

-- If it's a "new economy," why do they want my obsolete old money?

On Sun, 21 Sep 2003 22:38:02 -0500, "Ken Luther"
wrote:

Hello,

Can I use one of those cheap ol' Walmart power strips to as an isolation
transfomer (I need to work on my TS-940), or will I need to get a real
isolation transformer to prevent a ground loop.

A power strip is NOT an isolation device at all. You want to use a
transformer that completely isolated primary and secondary windings.

depends on how the rig is powered, but with a standard 3 wire plug,
you only need an isolation transformer if the chassis can be raised
above ground level. In something as sophisticated as ham radio gear,
where the chassis IS connected to ground, I'm not sure why you'd need
one.


If you need one, though, it's really cheap insurance.

Mostly needed in cheap TV sets and AC/DC radios, where the chassis is
directly grounded to the neutral of the AC line.

Harvey



The reason I ask, is that about 15 years ago while in tech school, one of my
buddies was working on a TV (NOT plugged in to an isolation transformer)
using an OScope (NOT plugged it to an isolation transformer, either), and
boy was he really suprised when that probe scratched against the chassis on
the tv set.

73's
Ken
KD5ZCL

On Sun, 21 Sep 2003 22:38:02 -0500, "Ken Luther"
wrote:

Hello,

Can I use one of those cheap ol' Walmart power strips to as an isolation
transfomer (I need to work on my TS-940), or will I need to get a real
isolation transformer to prevent a ground loop.

A power strip is NOT an isolation device at all. You want to use a
transformer that completely isolated primary and secondary windings.

depends on how the rig is powered, but with a standard 3 wire plug,
you only need an isolation transformer if the chassis can be raised
above ground level. In something as sophisticated as ham radio gear,
where the chassis IS connected to ground, I'm not sure why you'd need
one.


If you need one, though, it's really cheap insurance.

Mostly needed in cheap TV sets and AC/DC radios, where the chassis is
directly grounded to the neutral of the AC line.

Harvey



The reason I ask, is that about 15 years ago while in tech school, one of my
buddies was working on a TV (NOT plugged in to an isolation transformer)
using an OScope (NOT plugged it to an isolation transformer, either), and
boy was he really suprised when that probe scratched against the chassis on
the tv set.

73's
Ken
KD5ZCL

On Mon, 22 Sep 2003 00:52:49 -0500, Scott Schrader
wrote:

if you are servicing hot-chassis equipment, It Is INCUMBENT that you
power it through an isolation transformer to avoid becoming worm bait.
nothing else is safe.

the other way to say that is you don't use one, you die and/or burn the
place down and also kill the gear you're working on.

I got a nice 500-watter from a surplus outfit for $40 a couple months
ago. forget the name of the joint, something like skyline surplus just
outside cape canaveral. google for it, or do a search on slashdot,
which is where I got twigged to it.

Skycraft surplus. They're in Orlando, about 1 1/2 hours west of
Canaveral.

Nice place.

Harvey


you will also find this is an item that surplus stores can't keep in
stock, so they keep making deals and offering them. there is no good
reason except having way more money than you can bear to spend several
hundred dollars for one with a test-equipment company name on it.

Ken Luther wrote:

Hello,

Can I use one of those cheap ol' Walmart power strips to as an isolation
transfomer (I need to work on my TS-940), or will I need to get a real
isolation transformer to prevent a ground loop.

The reason I ask, is that about 15 years ago while in tech school, one of my
buddies was working on a TV (NOT plugged in to an isolation transformer)
using an OScope (NOT plugged it to an isolation transformer, either), and
boy was he really suprised when that probe scratched against the chassis on
the tv set.

73's
Ken
KD5ZCL

-- If it's a "new economy," why do they want my obsolete old money?

On Mon, 22 Sep 2003 00:52:49 -0500, Scott Schrader
wrote:

if you are servicing hot-chassis equipment, It Is INCUMBENT that you
power it through an isolation transformer to avoid becoming worm bait.
nothing else is safe.

the other way to say that is you don't use one, you die and/or burn the
place down and also kill the gear you're working on.

I got a nice 500-watter from a surplus outfit for $40 a couple months
ago. forget the name of the joint, something like skyline surplus just
outside cape canaveral. google for it, or do a search on slashdot,
which is where I got twigged to it.

Skycraft surplus. They're in Orlando, about 1 1/2 hours west of
Canaveral.

Nice place.

Harvey


you will also find this is an item that surplus stores can't keep in
stock, so they keep making deals and offering them. there is no good
reason except having way more money than you can bear to spend several
hundred dollars for one with a test-equipment company name on it.

Ken Luther wrote:

Hello,

Can I use one of those cheap ol' Walmart power strips to as an isolation
transfomer (I need to work on my TS-940), or will I need to get a real
isolation transformer to prevent a ground loop.

The reason I ask, is that about 15 years ago while in tech school, one of my
buddies was working on a TV (NOT plugged in to an isolation transformer)
using an OScope (NOT plugged it to an isolation transformer, either), and
boy was he really suprised when that probe scratched against the chassis on
the tv set.

73's
Ken
KD5ZCL

-- If it's a "new economy," why do they want my obsolete old money?