Flex6600 question Two SCU's Receive Protection

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A new owner of a Flex6600 asked me this question that just got his Flex6600

his e-mail to me is below
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I did go ahead and purchase a Flex 6600.  Since I still work, I have only fit in a few hours over the last week cabling it up and trying digital and SSB
on the first antenna jack ANT1.

Can you help me with one STUPID QUESTION:  
Since this is my very first expensive two SCU radio,I wanted to double check something before I make a $$$ mistake;

Tonight I have connected my second antenna to ANT2, and told a second
panadapter to use ANT2 to receive on a different band.  I assume this means I 
am using SCU #2 for the first time.   It is working in receive.  

Now for TX:   Is it correct and safe to assume that if I select a panadapter and 
start to transmit, the Flex rig should mute/short all the other antenna jacks so
I don't blow up the other antenna inputs/receivers (other SCU)?

When I only had ANT1 connected, no worries, no concern.
Now that ANT2 is also connected, I don't what to transmit until I understand
that the Flex rig will switch out and protect those other ANT or RX inputs?

Neal  N6YFM

Any help appreciated
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mikeatthebeach .

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Posted 2 weeks ago

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Photo of Ria - N2RJ

Ria - N2RJ, Elmer

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 Is it correct and safe to assume that if I select a panadapter and 
start to transmit, the Flex rig should mute/short all the other antenna jacks so
I don't blow up the other antenna inputs/receivers (other SCU)?
You must disable FDX (full duplex) for this to happen. This will enable the behavior you describe. If full duplex is on, the other SCU will be receiving while you're transmitting and you can blow it up unless you have sufficient filtering and/or separation.

Now, with that said the 6600 does have 7th order filters. However, you must still be careful. Also, the radio does have good protection at several layers. First of all, it will shut down if it detects excessive RF. Secondly, if that fails, the radio has protection diodes which will sacrifice themselves first before RF reaches the SCU. It still reqiures a repair, just not an expensive one.
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mikeatthebeach .

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Thanks Ria
  Also the 7th Order filters are only on Contest Bands, not all bands, like
the  WARC Bands !!!
Only Contest Bands have 7th order Filters
This is only for Flex6600 only and not other models !
73 Mike
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Ria - N2RJ, Elmer

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Generally you'll have issues with harmonically related bands. 

So if you're transmitting on 80, you'll see the 2nd harmonic on 40. Transmitting on 20, you'll see the 2nd harmonic on 10. 

With WARC bands, you have roughly 10, 18 and 25 MHz. So other bands really don't have potential to cause problems - provided you are not in WIDE mode. On the WARC bands you still have 3rd order filters like other radios. 

I have had some "oops" moments as every contester does. My radio simply admonished me and shut down. No damage at all. Some do have damage but the possibility is less because of the smart protection in the radio. 
(Edited)