Receive Antenna Ports

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  • Question
  • Updated 10 months ago
Do the 6000 series radio's have any better protection on the receive antenna ports than on the 5000A ? 
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FRED W9TB

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Posted 10 months ago

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Bill -VA3WTB

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Official Response From Steve

In general there is 40-50dB isolation between ANT1 and ANT2 and >90dB between ANT1/2 and RX A, RX B or XVTR.  This is, then, added to the antenna isolation you have at your site.  If you have concerns about this, one of the good ways to test is to set your radio for 1W and then try combinations and measure what you see in the panadapter.  The radio is calibrated at 1W so you should be able to calculate isolation and extrapolate without any concerns.  There is also a worksheet to help you determine if you need more isolation here: FLEX-6000 FDX Power Calculation Worksheet
(Edited)
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Tim - W4TME, Customer Experience Manager

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What type of protection?  If you are referring to static, EMP or high RF fields, the FLEX-5000, FLEX-3000, FLEX-1500 and all of the FLEX-6000s incorporate some sort of sacrificial component in the RF input signal path that is designed to interrupt the signal path (burn out) before serious damage is done to expensive components.

In the case of the 5000, it was components on the RFIO board.  For the FLEX-6000s, there are ESD diodes (depending on the model, there can be more than one) designed to clamp or in extream cases, burn out before the ADC is damaged (a really expensive part).
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Stan - VA7NF

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As this is a by-design burn out device, and that is a good thing, will Flex manufacture and market as a benefit, field replaceable protection devices.
I don't live in a lightning prone area but accidents still happen.
Call it a fuse for front end protection.
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Ken - NM9P, Elmer

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I can also verify that the ESD devices work.  I had a nearby strike when I didn't even expect any precip, and the ESD's sacrificed themselves and took the brunt of the damage.

I figure that the roughly $225 repair & shipping I had to pay was cheap considering what it could have been.

Of course...nothing would protect against a direct hit!

Ken - NM9P
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Bill -VA3WTB

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Tim I was looking at the site you posted, there are lots there. What model are you using, I don't know what I'm looking for.
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Tim - W4TME, Customer Experience Manager

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First off, pick your connector (UHF or N) then your frequency range.  The power handling is probably not of any consequence because who is running 10 KW?

For HF/6 I use this one with SO-239 connectors
https://www.arraysolutions.com/surge-and-rf-protection/as-303u

For anything above 54 MHz I use this one with N connectors
https://www.arraysolutions.com/surge-and-rf-protection/as-302n
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Bill -VA3WTB

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Thank you Tim
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Corey/ KC0YNS

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Thanks Tim, I've had good luck with the Polyphasers, Wish I had the grounding all the way around my house like you have. I'm using three 8 ft rods on each tower all tied together along with 3 outside my shack, All 8 ft rods.
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Peter John

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Hi...as per my knowledge about the 5000, it was components on the RFIO board.  For the FLEX-6000s, there are ESD diodes designed to clamp or in extream cases, burn out before the ADC is damaged.
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Andrew Russell

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Is the antenna port disconnected from the ESD diodes and ADC when powered off?
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Tim - W4TME, Customer Experience Manager

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The ESD diodes are always in the RF input signal path ahead of the ADC regardless of the antenna selected.
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Andrew Russell

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Even when the radio is in standby or powered off?
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Tim - W4TME, Customer Experience Manager

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Yes.
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Andrew Russell

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So when I turn the radio to unpowered or to standby the last antenna port used is still connected to the ADC via the ESD device. Have I got it yet?
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Dave Gipson

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As one who has more than a little experience working in RF design labs on Tempest and EMI hardened radios, the engineering behind FlexRadios is not lost on me. ESD is the "fundamental" basis of hardened radios and to a lesser extent, Tempest. 

I would venture to guess that "most" manufacturers of amateur radio equipment do not build to these standards. It is simply another unheralded but very important distinction between FlexRadios and the others.