EMP protection using loop circuit.

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  • Updated 2 years ago
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Hi Tim,

To make sure I understand it right. A preselector added in between the RXA input and RXA
output will have EMP protection or do I have to have protection added myself. This is only in
the single antenna, one receiver situation. Only using single SCU.
Thanks.

73, Jim N9VC
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N9VC

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Posted 2 years ago

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George Molnar, KF2T, Elmer

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Unlikely that a preselector would provide meaningful EMP protection. For true EMP, about the only thing that gives you a chance is disconnection and isolated, shielded storage. For lightning protection, also unlikely the preselector will save you from a direct strike. It might be the "sacrificial" component in some cases, it I wouldn't count on it for any protection.
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N9VC

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Hi George,

I am aware of that and I am not worried about the preselector although I
will add protection before the input. I am worried about the radio.

73, Jim N9VC
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Tim - W4TME, Customer Experience Manager

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Official Response
The EMP protection for the 6700 is done in the SCUs.  There are sacrificial ESD diodes before and after the preselector filters.  There is also a disconnect relay to ground the RF input signal path if the input signal threshold approaches the damage point of the SCU.  All of this is after the antenna switching matrix.  So any device in the RX Loop is before any of the the ESD protection.
(Edited)
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N9VC

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Hi Tim,

That is what I was looking for in your answer. Rest assured I disconnect
whenever I am not using the 6700. I just did not want to leave the 6700
at risk when I would be using the setup. I plan on protection before the
input of the preselector. But I will not be doing full-duplex or such. I use
it as a single SCU so when I transmit that should be removed from the
circuit by relays internal to the 6700. Some might wonder why did I get
rid of my 6500 and get the 6700 since I do not use the features. Simple.
The prestige of having the best instead of second-best :-)
And I might not even do the preselector as I have yet to encounter any
problem where I thought It would help. It would be the MFJ 1046 mainly
for help on 160 or lower. I like to listen for the 472 KHz beacons.

73, Jim N9VC
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N9VC

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You can close the thread if you wish. I think I have the answer.
Thanks again.

73, Jim N9VC

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