K-3: Unswitched Rx Ant

[RLVZ]

Hi Guys,

Please correct me if I'm wrong, but I believe the K-3 Receive Antenna is
unswitched during tranmit... which allows high RF to get back into the
receiver.  That's sure the case when using my beverage for receive and transmitting
on 160-meters.  (sounds like my K-3 is going to blow up)  I'm wondering why
this is the case.  Couldn't an inexpensive relay be added to the KXV3 to
prevent his problem?

I'd appreciate knowing what others are doing to prevent your K-3's from
blowing up while using  beverages on 160-meters!  Is everyone building an
external relay box just to switch the beverage off during transmit?  

Thanks & 73,

Dick- K9OM



   
   
   
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[wayne burdick]

Dick,

The RX ANT IN jack is electrically isolated from the rest of the  
circuitry during transmit via a pair of PIN diodes. If the signal  
level is high, an associated COR (carrier-operated relay) is also  
kicked in. So what you're experiencing is not normal.

However, we do advise keeping RX-only antennas as far from high-power  
transmit antennas as possible so that the COR will not activate during  
transmit. This minimizes risk of damage to the PIN diodes.

If you continue to have such an issue, please contact k3support for  
other suggestions and possible troubleshooting information.

73,
Wayne
N6KR

On Jan 24, 2011, at 10:18 PM, [hidden email] wrote:

> Hi Guys,
>
> Please correct me if I'm wrong, but I believe the K-3 Receive  
> Antenna is
> unswitched during tranmit... which allows high RF to get back into the
> receiver.  That's sure the case when using my beverage for receive  
> and transmitting
> on 160-meters.  (sounds like my K-3 is going to blow up)  I'm  
> wondering why
> this is the case.  Couldn't an inexpensive relay be added to the  
> KXV3 to
> prevent his problem?
>
> I'd appreciate knowing what others are doing to prevent your K-3's  
> from
> blowing up while using  beverages on 160-meters!  Is everyone  
> building an
> external relay box just to switch the beverage off during transmit?
>
> Thanks & 73,
>
> Dick- K9OM
>
>
>
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

______________________________________________________________
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[Charley]

Dick,

The RX ANT IN jack is electrically isolated from the rest of the  
circuitry during transmit via a pair of PIN diodes. If the signal  
level is high, an associated COR (carrier-operated relay) is also  
kicked in. So what you're experiencing is not normal.

However, we do advise keeping RX-only antennas as far from high-power  
transmit antennas as possible so that the COR will not activate during  
transmit. This minimizes risk of damage to the PIN diodes.

If you continue to have such an issue, please contact k3support for  
other suggestions and possible troubleshooting information.

73,
Wayne
N6KR

On Jan 24, 2011, at 10:18 PM, [hidden email] wrote:

> Hi Guys,
>
> Please correct me if I'm wrong, but I believe the K-3 Receive  
> Antenna is
> unswitched during tranmit... which allows high RF to get back into the
> receiver.  That's sure the case when using my beverage for receive  
> and transmitting
> on 160-meters.  (sounds like my K-3 is going to blow up)  I'm  
> wondering why
> this is the case.  Couldn't an inexpensive relay be added to the  
> KXV3 to
> prevent his problem?
>
> I'd appreciate knowing what others are doing to prevent your K-3's  
> from
> blowing up while using  beverages on 160-meters!  Is everyone  
> building an
> external relay box just to switch the beverage off during transmit?
>
> Thanks & 73,
>
> Dick- K9OM
>
>
>
>
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

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[K5WA]

Dick,

My 1000' beverages are WAY too close to my 160 phased vertical array (about
100' max at the closest point) running the legal limit power but I have zero
RF getting back into the K3 when transmitting and I use NO external relays
to protect the K3.  I have K3 S/N 234 and 752 and I believe I remember
adding the strong signal overload mod since these are older models, but I've
only seen that COR activated one time when I was playing around on the
workbench.  I've never seen it kick in during normal operation.  Something
has to be abnormal with your installation or the rig itself.  Like Wayne
says, [hidden email] can help you figure it out.  

I hope to see you this weekend in the CQWW 160 contest because I'll be
plowing away to the best of my staying awake powers.  ;-)

GL,
Bob K5WA


>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Message: 26
Date: Tue, 25 Jan 2011 01:18:25 EST
From: [hidden email]
Subject: [Elecraft] K-3: Unswitched Rx Ant
To: [hidden email]
Message-ID: <[hidden email]>
Content-Type: text/plain; charset="US-ASCII"

Hi Guys,

Please correct me if I'm wrong, but I believe the K-3 Receive Antenna is
unswitched during tranmit... which allows high RF to get back into the
receiver.  That's sure the case when using my beverage for receive and
transmitting
on 160-meters.  (sounds like my K-3 is going to blow up)  I'm wondering why
this is the case.  Couldn't an inexpensive relay be added to the KXV3 to
prevent his problem?

I'd appreciate knowing what others are doing to prevent your K-3's from
blowing up while using  beverages on 160-meters!  Is everyone building an
external relay box just to switch the beverage off during transmit?  

Thanks & 73,

Dick- K9OM


______________________________________________________________
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[Bill W4ZV]

K5WA wrote

My 1000' beverages are WAY too close to my 160 phased vertical array (about
100' max at the closest point) running the legal limit power but I have zero
RF getting back into the K3 when transmitting and I use NO external relays
to protect the K3.

Same here.  I've never had problems using 4 different rigs (TS-930S, FT-1000MP, Orion and K3) running legal limit power to verticals with Beverages nearby (once even over elevated radials at my Colorado QTH).  If you pay careful attention to common mode reduction (i.e. isolating ground returns) I don't think you need "front end savers", etc.

CU in the CQ 160 this weekend...band sounds like it may be improving.

73,  Bill