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Old 04-09-2016, 06:58   #1
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Can two HF radios safely use one dynaplate on a sailboat.

Can two HF radios safely use one dynaplate on a sailboat.

I have a icom 718 and a newly aquired ic-728 I would like to use for PSK.

I would like to use both of them on the existing dynaplate ground plate. There is a chance both could be transmitting at the same time.

The advice I have so far is that the ground is common any way by all the other cables so having both hf radios on a single dynaplate will be fine.

Thanks in advance.
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Old 04-09-2016, 17:39   #2
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Re: Can two HF radios safely use one dynaplate on a sailboat.

yachtmanforfun,
The answer is, yes...
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Originally Posted by yachtmanforfun View Post
Can two HF radios safely use one dynaplate on a sailboat.


But, I do have some concern that you may need to keep your transmit/receive antennas separated more than you think...
And, on a 35' boat, you don't have the room to do this...
Understand that even if the bands of operation are different, one rig's transmitter WILL desense the other's receiver!! Therefore, operating both rigs at the same time will be problematic (meaning it will be a pain in the ass, at best....and at worst, a waste of time...)
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Originally Posted by yachtmanforfun View Post
I have a icom 718 and a newly aquired ic-728 I would like to use for PSK.

I would like to use both of them on the existing dynaplate ground plate. There is a chance both could be transmitting at the same time.

The advice I have so far is that the ground is common any way by all the other cables so having both hf radios on a single dynaplate will be fine.

Thanks in advance.
Hope this helps...

Fair winds...

John
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Old 08-09-2016, 13:24   #3
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Re: Can two HF radios safely use one dynaplate on a sailboat.

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Originally Posted by yachtmanforfun View Post
Can two HF radios safely use one dynaplate on a sailboat[?]
I suppose that "safely" is somewhat subjective. I suspect that you will be able to simultaneously transmit on both transmitters, however, I suggest you perform this test:

--transmit on HF radio A; record its VSWR

--transmit on HF radio B; record its VSWR

--transmit simultaneously on both A and B; I suspect the VSWR will change.

A change in VSWR indicates some interaction between the two transmitters.

If one or both antennas are being fed single-ended and worked against the sea via the Dynaplate ground, you may experience more interaction than anticipated when transmitting simultaneously.

Other operation, such as simultaneous receive or transmit on only one radio, won't be likely to be affected by sharing of the common Dynaplate grounding, unless one of the transmitters is very poorly bonded to the Dynaplate.

If you experiment, please post some findings.
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Old 08-09-2016, 13:38   #4
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Re: Can two HF radios safely use one dynaplate on a sailboat.

I have a common ground including dynaplate shared between two otherwise independent tranceivers on the boat however I never even leave #2 'on' when transmitting on #1 or v/v. Horizontal distance between ants is about a metre.

Ashore I have one transceiver on a G5RV which is about 20 metres away from any of my three RX ants. Transmitting doesn't lead to smoke but can lead to considerable RX intereference. Photo tomorrow when I get back to the campo.
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Old 08-09-2016, 17:07   #5
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Re: Can two HF radios safely use one dynaplate on a sailboat.

Quote:
Originally Posted by continuouswave View Post
I suppose that "safely" is somewhat subjective. I suspect that you will be able to simultaneously transmit on both transmitters, however, I suggest you perform this test:

--transmit on HF radio A; record its VSWR

--transmit on HF radio B; record its VSWR

--transmit simultaneously on both A and B; I suspect the VSWR will change.

A change in VSWR indicates some interaction between the two transmitters.

If one or both antennas are being fed single-ended and worked against the sea via the Dynaplate ground, you may experience more interaction than anticipated when transmitting simultaneously.

Other operation, such as simultaneous receive or transmit on only one radio, won't be likely to be affected by sharing of the common Dynaplate grounding, unless one of the transmitters is very poorly bonded to the Dynaplate.

If you experiment, please post some findings.
Quote:
Originally Posted by continuouswave View Post
I suppose that "safely" is somewhat subjective. I suspect that you will be able to simultaneously transmit on both transmitters, however, I suggest you perform this test:

--transmit on HF radio A; record its VSWR

--transmit on HF radio B; record its VSWR

--transmit simultaneously on both A and B; I suspect the VSWR will change.

A change in VSWR indicates some interaction between the two transmitters.



If you experiment, please post some findings.

Thanks for responding. I think that having some interference between the radios is acceptable , as long as they do not electronically affect each other.

I will do your test and report back. It will be a few weeks.


I plan to have a 1.8 m fiberglass spreader on top of my mast and have the HF antennas come down to either side of my solar panels. so I estimate the antennas will be 1.8 m apart at top and 3 m at the bottom.
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Old 08-09-2016, 17:09   #6
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Re: Can two HF radios safely use one dynaplate on a sailboat.

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Originally Posted by El Pinguino View Post
I have a common ground including dynaplate shared between two otherwise independent tranceivers on the boat however I never even leave #2 'on' when transmitting on #1 or v/v. Horizontal distance between ants is about a metre.

Ashore I have one transceiver on a G5RV which is about 20 metres away from any of my three RX ants. Transmitting doesn't lead to smoke but can lead to considerable RX intereference. Photo tomorrow when I get back to the campo.

I will most likely be experimenting with both radios and expect in rare situations they could transmit at same time.

Ie Winlink email on one and PSK on the other.
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Old 09-09-2016, 05:04   #7
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Re: Can two HF radios safely use one dynaplate on a sailboat.

I think you should be prepared for applications like Winlink to not work when the other radio is transmitting, Applications like Winkink and Sailmail require decent receive performance. Most receivers will be adversely affected by a nearby transmitter within a wavelength of the receive antenna. So you should not expect this to work. The common dynaplate is not a big problem in my opinion.
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Old 09-09-2016, 06:16   #8
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Re: Can two HF radios safely use one dynaplate on a sailboat.

Ground plane/dynaplate is just as much part of the antenna as is the antenna itself (monopole), whip or backstay isolated section. I would not transmit coherently and expect good results. VSWR measurements sound like a good idea, b/c transmitted energy from one radio will go into antenna as well as into the other radio.
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Old 09-09-2016, 15:16   #9
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Re: Can two HF radios safely use one dynaplate on a sailboat.

As promised... the effect of tuning up on 14 MHz while listening on 7 MHz.

G5RV TX, random longwire RX , 15/20 metre separation.

As stated above transmitting on one would most likely knock out the reception of digital modes on the other.
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