A/B Switching
 

I recently put an A/B switch between my FT-1000 MPV and my IC-746 to
make comparisons between receivers. I would now like to leave this
A/B switch in line, as I would like to use one radio for CW, and the
other for SSB. The IC-746 is known for having a sensitive front end
(easy to damage). I am running 200 watts from the FT-1K. The A/B
switch grounds the unused port. My fear is that the FT-1K will damage
the front end of the IC-746, even as the IC-746 port is grounded.

I have to assume, no matter how diligent I think I will be, at some
point in time, both receivers will be on the same band, near the same
frequency.

Is it probable that the grounded loop to the 746, being 1/8 inch from
200 watts, will survive without damage?

Has anyone operated an IC-746 under these conditions?

Win, W0LZ

A/B Switching
 

"Win" wrote in message
...
I recently put an A/B switch between my FT-1000 MPV and my IC-746 to
make comparisons between receivers. I would now like to leave this
A/B switch in line, as I would like to use one radio for CW, and the
other for SSB. The IC-746 is known for having a sensitive front end
(easy to damage). I am running 200 watts from the FT-1K. The A/B
switch grounds the unused port. My fear is that the FT-1K will damage
the front end of the IC-746, even as the IC-746 port is grounded.

I have to assume, no matter how diligent I think I will be, at some
point in time, both receivers will be on the same band, near the same
frequency.

Is it probable that the grounded loop to the 746, being 1/8 inch from
200 watts, will survive without damage?

Has anyone operated an IC-746 under these conditions?

Win, W0LZ

I have an IC756 and FT847 going to the same (HF) A/B switch. No problems.
You will want to do this on the input side of any amplifier.

Tam/WB2TT

A/B Switching
 

"Win" wrote in message
...
I recently put an A/B switch between my FT-1000 MPV and my IC-746 to
make comparisons between receivers. I would now like to leave this
A/B switch in line, as I would like to use one radio for CW, and the
other for SSB. The IC-746 is known for having a sensitive front end
(easy to damage). I am running 200 watts from the FT-1K. The A/B
switch grounds the unused port. My fear is that the FT-1K will damage
the front end of the IC-746, even as the IC-746 port is grounded.

I have to assume, no matter how diligent I think I will be, at some
point in time, both receivers will be on the same band, near the same
frequency.

Is it probable that the grounded loop to the 746, being 1/8 inch from
200 watts, will survive without damage?

Has anyone operated an IC-746 under these conditions?

Win, W0LZ

My concern would be the port- port isolation of the A/B switch. Depending on
the mfg, they're all over the map.

Dale W4OP

A/B Switching
 

On Thu, 20 Jul 2006 12:56:35 GMT, "Dale Parfitt"
wrote:


"Win" wrote in message
.. .
I recently put an A/B switch between my FT-1000 MPV and my IC-746 to
make comparisons between receivers. I would now like to leave this
A/B switch in line, as I would like to use one radio for CW, and the
other for SSB. The IC-746 is known for having a sensitive front end
(easy to damage). I am running 200 watts from the FT-1K. The A/B
switch grounds the unused port. My fear is that the FT-1K will damage
the front end of the IC-746, even as the IC-746 port is grounded.

I have to assume, no matter how diligent I think I will be, at some
point in time, both receivers will be on the same band, near the same
frequency.

Is it probable that the grounded loop to the 746, being 1/8 inch from
200 watts, will survive without damage?

Has anyone operated an IC-746 under these conditions?

Win, W0LZ

My concern would be the port- port isolation of the A/B switch. Depending on
the mfg, they're all over the map.

Dale W4OP


Dale, the one I have is a XS201, cast iron, much like the MFJ. I
would consider buying a better switch, though, if you could recommend
one.

Win, w0lz

A/B Switching
 

"Win" wrote in message
...
On Thu, 20 Jul 2006 12:56:35 GMT, "Dale Parfitt"
wrote:


"Win" wrote in message
. ..
I recently put an A/B switch between my FT-1000 MPV and my IC-746 to
make comparisons between receivers. I would now like to leave this
A/B switch in line, as I would like to use one radio for CW, and the
other for SSB. The IC-746 is known for having a sensitive front end
(easy to damage). I am running 200 watts from the FT-1K. The A/B
switch grounds the unused port. My fear is that the FT-1K will damage
the front end of the IC-746, even as the IC-746 port is grounded.

I have to assume, no matter how diligent I think I will be, at some
point in time, both receivers will be on the same band, near the same
frequency.

Is it probable that the grounded loop to the 746, being 1/8 inch from
200 watts, will survive without damage?

Has anyone operated an IC-746 under these conditions?

Win, W0LZ

My concern would be the port- port isolation of the A/B switch. Depending
on
the mfg, they're all over the map.

Dale W4OP


Dale, the one I have is a XS201, cast iron, much like the MFJ. I
would consider buying a better switch, though, if you could recommend
one.

Win, w0lz


Hi Win,
I have little expereience with the different manufactures of HF switches. My
experience is in relays for 1296 MHz LNA protection- and the port-port
isolation is all over the board.
Ask the manufacturers if they have this spec.
Dale W4OP

A/B Switching
 

Thanks, Dale.

I will do that. So far, I have found, as you said, the claims are all
over the board. In the data sheets I have been able to locate, I have
seen numbers from 20db to 80db down. Something in the area of 80db
would sure do the trick, if I can believe them, HI.

Win, W0LZl



On Sat, 22 Jul 2006 13:54:34 GMT, "Dale Parfitt"
wrote:


"Win" wrote in message
.. .
On Thu, 20 Jul 2006 12:56:35 GMT, "Dale Parfitt"
wrote:


"Win" wrote in message
...
I recently put an A/B switch between my FT-1000 MPV and my IC-746 to
make comparisons between receivers. I would now like to leave this
A/B switch in line, as I would like to use one radio for CW, and the
other for SSB. The IC-746 is known for having a sensitive front end
(easy to damage). I am running 200 watts from the FT-1K. The A/B
switch grounds the unused port. My fear is that the FT-1K will damage
the front end of the IC-746, even as the IC-746 port is grounded.

I have to assume, no matter how diligent I think I will be, at some
point in time, both receivers will be on the same band, near the same
frequency.

Is it probable that the grounded loop to the 746, being 1/8 inch from
200 watts, will survive without damage?

Has anyone operated an IC-746 under these conditions?

Win, W0LZ

My concern would be the port- port isolation of the A/B switch. Depending
on
the mfg, they're all over the map.

Dale W4OP


Dale, the one I have is a XS201, cast iron, much like the MFJ. I
would consider buying a better switch, though, if you could recommend
one.

Win, w0lz


Hi Win,
I have little expereience with the different manufactures of HF switches. My
experience is in relays for 1296 MHz LNA protection- and the port-port
isolation is all over the board.
Ask the manufacturers if they have this spec.
Dale W4OP