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Old 05-06-2018, 13:41   #1
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Multiple antenna for ham/marine

I intend to run a TS-480hx/sgc230 and a M802/AT-140. My original thought was to use a backstay antenna with the Kenwood and a whip with the Icom.

That is until I considered using 2 antenna switches to interconnect them.

Will quality antenna switches create significant losses?

Any recommendations for switches?

Would it be functionally better to keep them separated?

Thanks for any help and for all the great information on this site.
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Old 06-06-2018, 11:51   #2
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Re: Multiple antenna for ham/marine

The backstay antenna should out perform the whip antenna in most cases. I use high quality antenna switches at my base station, losses are insignificant.
Question- why are you bothering with the TS480 (same as I use) when you can use the 802 on all freqs? I would use the sgc tuner with the 802 and backstay antenna for a perfect setup.
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Old 06-06-2018, 12:55   #3
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Multiple antenna for ham/marine

M802 is, for me, not a pleasure to use for ham purposes. Doable, yes. If all you want to do on ham bands is voice comms, itís fine I suppose.

Even MFJ antenna switches introduce negligible loss. Higher quality/reliability may be found with other brands.
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Old 06-06-2018, 13:24   #4
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Re: Multiple antenna for ham/marine

Icom 802 is very easy to use on ham bands especially when memories are used for fast band changes. Interfaces easily with scs pactor modem for winlink.
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Old 06-06-2018, 19:40   #5
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Re: Multiple antenna for ham/marine

Boca and Sooner, I really appreciate the help.

Why bother with the TS480? I already own it. It is a great rig.

The reason for both back-stay and whip would be for redundancy.

Thanks for the info.
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Old 07-06-2018, 06:29   #6
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Re: Multiple antenna for ham/marine

I don't understand your intentions about the antenna switch.

I assume you will use each radio in conjunction with its own tuner, and then have some switching arrangement to connect one of the two tuner's antenna connection to the single backstay end-fed wire.

Because the impedance of the antenna at the base feed point will be highly variable depending on frequency, there could be substantial voltage there. Any switch that is intended to connect the base of the antenna to one or two tuners would have to be able to tolerate the high voltage that could be present.

Since the power level will be modest, probably less than 100-watts delivered to the antenna (and here I am figuring the transmitter puts out 100-watts but some of that is lost in the tuner), you MIGHT be okay with a typical 50-Ohm coaxial transmission line switch. But you might not be, if the length of the backstay happens to be a half-wavelength at the operating frequency.

I suspect that the feedline to the backstay antenna is probably some high-voltage insulated wire. You could arrange the tuners to be close to this wire, and just connect the antenna wire to the tuner you want to use, perhaps using something like a banana plug fitting on the wire and two mating banana jacks, one on each tuner's ANTENNA post.
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Old 07-06-2018, 06:53   #7
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Re: Multiple antenna for ham/marine

Continuouswave, not to be disrespectful but there is a lot of misinformation in your post.


My suggestion to roblanford, since he is looking for redundancy is to install the 480 and 802 on an antenna switch. Use the sgc tuner, which is a much better tuner than the Icom, feed the backstay antenna. Sound like you have a good rf ground in place.


If you have any other questions, contact me offline via w4grj@arrl.net
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Old 07-06-2018, 19:12   #8
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Re: Multiple antenna for ham/marine

Quote:
Originally Posted by BocaIII View Post
Continuouswave...there is a lot of misinformation in your post.
There can't be any misinformation in my post, because, as I clearly said to the OP:

"I don't understand your intentions about the antenna switch."

I don't have a clear understanding of what the OP intends to do. I laid out what I think he is planing to do as I understood him, and told him the problem with that approach.

Now I have a clear understanding of what you think the OP intends to do, but that is perhaps just as much misinformation as my understanding. Perhaps the OP can clear up his intentions.

Also, I'd think there would be more redundancy in having two tuners, and also more utility. One rig might be tuned up for 7.1-MHz and the other rig might be tuned up for a marine band channel. By just switching the antenna, the tuner would already be pre-tuned.
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Old 08-06-2018, 07:52   #9
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Re: Multiple antenna for ham/marine

Robert, et al,
1) If you're referring to "coax switches" intended to switch the feedlines for different antennas (or switch in different transceivers, etc.), and you're intended application is to attempt to use these to switch the GTO-15 antenna wire (from backstay) between two tuners???
Then "continuouswave" is correct....and this is NOT a good idea...
And, you'd need to use a hi-voltage antenna switch, not a "coax switch"....or as you mention, use separate antennas..

2) {If your intended application is to switch the two different transceivers (M-802 and TS-480) between ONE tuner and antenna (SG-230 and backstay), then, yes a simple coax switch (such as a Diawa CS-201 or AlphaDelta) will work...as long as you're powering the SG-230 independently (NOT thru the coax, with power-injector)...}

3) But, using what you wrote, I'm assuming your intention is what you wrote (and what I described in #1)??
So, if that is what you want to do:

How do you do it??
What are your options???
Quote:
Originally Posted by roblanford View Post
I intend to run a TS-480hx/sgc230 and a M802/AT-140. My original thought was to use a backstay antenna with the Kenwood and a whip with the Icom.
Actually, I'd reverse this approach!! Use the M-802 on the backstay!!
The M-802 is going to be your primary radio and with solar activity on the serious decline (bottoming-out in 2020, and not starting to rise again 'til 2022) the lower freq bands (4, 6, 8mhz, as well as 75m and 40m ham bands) will be VERY good (with 12mhz, and 20m ham band, only useful during the day...and I expect some days in the next couple years, these bands will be dead for high-latitude paths, and maybe even unusable in the tropics for some hours), the longer antenna (backstay) will be your primary antenna!!
You will be amazed at how much better your longer transmit antenna will be on 4mhz (as well as 6mhz and 8mhz) compared to a 23' whip!
{this difference can also be noticed on 12mhz and 14mhz, but to a much lesser extent}


If you wish to keep the TS-480HX/SG-230, as a redundant system....then yes, rig them up as a separate system and depending on what boat you have, you may need to use a whip?? or insulated shroud?? or mizzen backstay??
(you don't mention anything about your boat, your other on-board systems, solar, etc...nor anything about where you are planning on sailing/cruising, what you comms needs are, etc. etc...so I cannot be too specific here, just generalizing...sorry...)


As for the SG-230??
Well, in years past this was the gold standard....but in the past 8-10 years, SGC has had some serious quality-control issues and I've personally had SGC tuners dead-on-arrival, and another "repaired" by the factory, just to fail again in 2 months....and have heard of others with these same QC issues....
So, if your SG-230 is an older unit, you should be fine....if it is new, then I will recommend caution...(and if it is a new unit, I'd recommend installing the AT-140, and having it at the ready, should the SG-230 fail)
Further, I highly recommend the AT-140 tuner....and if it weren't that you wish to use the TS-480 and you don't have a "Icom tuner interface box", then I'd say use the AT-140...


That is until I considered using 2 antenna switches to interconnect them.
Will quality antenna switches create significant losses?
Any recommendations for switches?
If for some reason you wish to do something different from the above recommendation??
Although, I think this is an inelegant and somewhat cumbersome approach, not to mention introducing another component into the mix (especially one that is not really designed for rugged marine use), you could rig a high-voltage "knife-switch" transfer switch, to switch the two separate transceiver/tuner combinations (M-802/AT-140 and TS-480HX/SG-230), in order to switch the GTO-15 wire between them...
(I've used these before in hi-power / high-voltage balanced feeder switching and while they do work, and introduce little if any loss, they usually have bare copper connections and would need to be plated or tinned and kept clean and dry....not a easy job on an offshore boat...)

Please note that this is not an application where low-impedance "coax-switches" are recommended...



Would it be functionally better to keep them separated?
Actually, while the TS-480HX is a nice rig (and has nice audio), the M-802 is the better radio....
If it were me??
I'd design the system with the M-802/AT-140, including a DSC-receive antenna, and decent antenna ground system (see link, for details)...
Use this as your primary (only?) HF rig, on both maritime and ham bands...
And, "install" and wire-up the TS-480HX and SG-230, as a secondary system, but keep it disconnected / unplugged from everything...(plug it in and test it / use it for an hour or so, every couple months, to keep everything "fresh") OR....or just install the wiring for the TS-480HX/SG-230, and wrap-up them up and stow 'em as spares!!

Use the backstay!!
The M-802 is going to be your primary radio...

And with solar activity on the serious decline (bottoming-out in 2020, and not starting to rise again 'til 2022) the lower freq bands (4, 6, 8mhz, as well as 75m and 40m ham bands) will be VERY good (with 12mhz, and 20m ham band, only useful during the day), the longer antenna (backstay) will be your primary antenna!!
You will be amazed at how much better your longer transmit antenna will be on 4mhz (as well as 6mhz and 8mhz) compared to a 23' whip!
{this difference can also be noticed on 12mhz and 14mhz, but to a much lesser extent}


Thanks for any help and for all the great information on this site.
Please have a look at these threads/stickies (and watch the videos!)
HF-SSB Radio, Proper Installation Tips/Techniques, etc.

Marine SSB Stuff (how-to better use / proeprly-install SSB, & troubleshoot RFI, etc.)


Here are a LOT of videos that will help....(yes, for the experienced communications guys, you can fast-forward thru some parts....but, for most, these will help...a LOT)
Please note these videos were made a few years ago, when solar activity was higher....and with it getting even lower in coming years (won't be better 'til 2020), you will need to use one band LOWER in freq than shown in the videos....and at some point, possibly even two bands lower in freq...

HF-DSC Comms
https://www.youtube.com/playlist?lis...ga2zYuPozhUXZX

Maritime HF Comms
https://www.youtube.com/playlist?lis...ZDo_Jk3NB_Bt1y

Icom M-802 Instruction Videos
https://www.youtube.com/playlist?lis...rC-8QKVyMb4tVr
(video #3 discusses "VFO mode" / ham radio operations....and #5 shows some various live signals, including ham)

Offshore Weather
https://www.youtube.com/playlist?lis...zdjTJjHlChruyY


And, some others:
Offshore Sailing
https://www.youtube.com/playlist?lis...KgTCj15iyl6qoY

VHF-DSC
https://www.youtube.com/playlist?lis...J6QugtO2epizxF



Here is Video #3, showing "VFO mode" and some ham radio operations...
Hesitant to post just this one, because taken out-of-context it could be confusing to some (and might look foolish to others)...
So please watch all of the videos in order, in the playlists above..





Robert, et al, there is more to this....and I can add detail....but, before I ramble on, it would be good to know exactly what your intentions are??
Where you're sailing/cruising, etc..
What your comms needs are??
Etc.
Etc.???

'Til then, I hope this helps...

Fair winds...

John
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Old 08-06-2018, 08:50   #10
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Re: Multiple antenna for ham/marine

As the seniors have said, keep one tuner and switch the feeds from the radio to the switch. Any coax switch will do. I believe there is no difference in the power out of the radio vs. out of the tuner but the coax switches can handle it.

If you worry about a backup antenna, any wire of sufficient length lifted on a haliyard will do.

In practice you will end up using one of the radio though, probably the Kenwood. Just give it a few months and the decision will be obvious.
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Old 08-06-2018, 10:05   #11
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Re: Multiple antenna for ham/marine

Quote:
Originally Posted by Pizzazz View Post
...I believe there is no difference in the power out of the radio vs. out of the tuner....
You are welcome to your beliefs, but in practice there is often a possibility for loss in a tuning network, so the power out of a tuning network to the antenna is not intrinsically always going to be equal to the power input to the tuning network.

It is possible for a tuning network to present a match to 50-Ohms for a wide variety of loads, but there is no guarantee that the tuning network will have 100-percent efficiency, that is, no loss.

At 100-Watt power level a loss of 1 dB in the tuning network would be a loss of about 21-watts, and while the tuning network might have a temperature rise, it would not be particularly worrisome, especially when considering the duty-cycle of the transmitter is very very low.

Generally the possibility for loss in the tuning network will tend to increase when the impedance transformation being performed by the tuning network increases.
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Old 08-06-2018, 22:14   #12
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Re: Multiple antenna for ham/marine

Thanks for all the effort and time spent on advice. 2 of these run back to back between the radios and tuners should get the job done:



Sorry if my question was misleading.
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Old 09-06-2018, 00:12   #13
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Re: Multiple antenna for ham/marine

I know how a tuner works. The discussion was whether the switch should be before or after the tuner and the power handling capacity of the switch not about reflected power, etc.
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Old 09-06-2018, 00:33   #14
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Re: Multiple antenna for ham/marine

I deal with radio communications on a daily basis and am also an extra class so I understand where you are coming from.

What I'd do is just make the jumper cables long enough you can switch things around when you want to but otherwise leave them hardwired to their respective antennas until you decide differently. At that point you will have a better idea as to what will work for you and your tastes.
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Old 09-06-2018, 02:09   #15
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Re: Multiple antenna for ham/marine

Pizzaz-I too am pretty confident that the 480 will be the go to rig for Ham activities.

MB - keeping it simple makes a lot of sense. An IC802 to a whip will work for its intended purpose.

If I could just figure out how to set up my IC703 for mili-watting CW and my kx1 for QRP/MM-dinghy I will have it all covered.

Thanks again for the help.
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