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#1
July 19th 06, 04:14 PM
posted to rec.radio.amateur.antenna
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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 |
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#2
July 19th 06, 04:54 PM
posted to rec.radio.amateur.antenna
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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 |
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#3
July 20th 06, 01:56 PM
posted to rec.radio.amateur.antenna
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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 |
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#4
July 21st 06, 12:59 AM
posted to rec.radio.amateur.antenna
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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 |
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#5
July 22nd 06, 02:54 PM
posted to rec.radio.amateur.antenna
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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 |
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#6
July 22nd 06, 04:28 PM
posted to rec.radio.amateur.antenna
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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 |
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