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K3 SO2R Question

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Jim HaRRIS

K3 SO2R Question

Hi Folks,

I'm currently selling an off-shore rig with the hopes of acquiring a second K3 for SO2R, primarily for RTTY contesting. I believe I've seen somewhere in the not to distant past that is was said the K3 receive front end can withstand 1-2 watts without damage. I've spent the last hour reviewing the email archive and can find no reference to that. Can anyone confirm or deny my remembrance? (Or, is it all just wishful thinking?) Is there anyone on the reflector that is operating a K3 SO2R station without the thousand or so dollars of band pass filters needed to protect the radio's front end?

Second part of the question is.....if possible to not damage the front end, what is the possibility of desensing or causing blocking or noise that would interfere with reception on one receiver when transmitting on the other radio. I'm sure that is highly dependent on band(s) and separation of frequencies within the band. I'll fully aware of the K3's ability to completely block signals a few kilohertz away but when RTTY contesting I do seem to notice there may be some desensing or AGC action from these signals even though they are not heard or processed by MMTTY.

Comments very much appreciated.

CU in the Colorado QSO Party Sept 4th, 2010.

73, Jim, W0EM

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Bob Naumann W5OV

Re: K3 SO2R Question

Jim,

Are you asking if you can run high power SO2R and do so safely without
bandpass filters? You didn't mention what power level, and this makes a huge
difference.

You can use ICE bandpass filters (-30 to -35db) which are relatively cheap
(~$40 each). Their performance is not as good as W3NQN design filters (-75db
to -80db) which are the ones that cost big bucks(~$99 each). If you allocate
one radio to doing say 160, 40 and 15 and the other to doing 80, 20 and 10m,
you could get by with just one set of 6 bandpass filters.

While bandpass filters have a by-product of protecting your radio's front
end, that's not all they do. The filter on the transmitter limits what gets
out and the filter on the receiver limits what gets in - so having a filter
on each radio increases the benefit. This is more of a practical operational
thing than being protective.

Also, when you say "separation of frequencies within the band" do you intend
to run both radios on the same band? Needless to say, bandpass filters will
not be of any use if you do this. The key here is physical separation of
your antennas so that the coupling between the two is minimized.

Bob W5OV

P.S. ICE has a new owner and is delivering product again much more quickly.

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Jim Harris
Sent: Monday, March 08, 2010 4:03 PM
To: Elecraft Email
Subject: [Elecraft] K3 SO2R Question

Hi Folks,

I'm currently selling an off-shore rig with the hopes of acquiring a second
K3 for SO2R, primarily for RTTY contesting. I believe I've seen somewhere
in the not to distant past that is was said the K3 receive front end can
withstand 1-2 watts without damage. I've spent the last hour reviewing the
email archive and can find no reference to that. Can anyone confirm or deny
my remembrance? (Or, is it all just wishful thinking?) Is there anyone on
the reflector that is operating a K3 SO2R station without the thousand or so
dollars of band pass filters needed to protect the radio's front end?

Second part of the question is.....if possible to not damage the front end,
what is the possibility of desensing or causing blocking or noise that would
interfere with reception on one receiver when transmitting on the other
radio. I'm sure that is highly dependent on band(s) and separation of
frequencies within the band. I'll fully aware of the K3's ability to
completely block signals a few kilohertz away but when RTTY contesting I do
seem to notice there may be some desensing or AGC action from these signals
even though they are not heard or processed by MMTTY.

Comments very much appreciated.

CU in the Colorado QSO Party Sept 4th, 2010.

73, Jim, W0EM

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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______________________________________________________________
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Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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Tony Fegan VE3QF

Re: K3 SO2R Question

In reply to this post by Jim HaRRIS

Hi Jim,

I think this is the thread you are looking for:

http://n2.nabble.com/KRX3-Overload-Protection-on-160M-td3814157.html#a3814157

Hope this helps.
73
Tony Fegan VE3QF

Jim Harris wrote:

> Hi Folks,
>
> I'm currently selling an off-shore rig with the hopes of acquiring a
> second K3 for SO2R, primarily for RTTY contesting. I believe I've
> seen somewhere in the not to distant past that is was said the K3
> receive front end can withstand 1-2 watts without damage. I've spent
> the last hour reviewing the email archive and can find no reference
> to that. Can anyone confirm or deny my remembrance? (Or, is it all
> just wishful thinking?) Is there anyone on the reflector that is
> operating a K3 SO2R station without the thousand or so dollars of
> band pass filters needed to protect the radio's front end?
>
> Second part of the question is.....if possible to not damage the
> front end, what is the possibility of desensing or causing blocking
> or noise that would interfere with reception on one receiver when
> transmitting on the other radio. I'm sure that is highly dependent
> on band(s) and separation of frequencies within the band. I'll fully
> aware of the K3's ability to completely block signals a few kilohertz
> away but when RTTY contesting I do seem to notice there may be some
> desensing or AGC action from these signals even though they are not
> heard or processed by MMTTY.
>
> Comments very much appreciated.
>
> CU in the Colorado QSO Party Sept 4th, 2010.
>
> 73, Jim, W0EM
>
>
> ______________________________________________________________
> 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
>

Brett Howard

Re: K3 SO2R Question

In reply to this post by Jim HaRRIS

http://www.elecraft.com/K3/mods/K3%20rx%20protection%20mod,%20rev%20B.pdf

That document explains a mod that you should definitely make sure is
in place in your radio if you're worried about this condition. I had
one of Q8 and Q9 blow in my radio after too much power came back in
from another operator who told me he *WAS* staying off of 20 meter
like to told him to do he was down on 14 meters! ;) Anyway we
replaced the Q and the rig came back to life. But if you view that
document it says that when you get to +13 to +20dBm it will
automatically engage the preamp for you. +20dBm is 100mW so that
would at least give you an added 10dB of protection on your way up to
the 1-2W realm.

~Brett (KC7OTG)

On Mon, Mar 8, 2010 at 2:03 PM, Jim Harris <[hidden email]> wrote:

>
> Hi Folks,
>
> I'm currently selling an off-shore rig with the hopes of acquiring a second K3 for SO2R, primarily for RTTY contesting. I believe I've seen somewhere in the not to distant past that is was said the K3 receive front end can withstand 1-2 watts without damage. I've spent the last hour reviewing the email archive and can find no reference to that. Can anyone confirm or deny my remembrance? (Or, is it all just wishful thinking?) Is there anyone on the reflector that is operating a K3 SO2R station without the thousand or so dollars of band pass filters needed to protect the radio's front end?
>
> Second part of the question is.....if possible to not damage the front end, what is the possibility of desensing or causing blocking or noise that would interfere with reception on one receiver when transmitting on the other radio. I'm sure that is highly dependent on band(s) and separation of frequencies within the band. I'll fully aware of the K3's ability to completely block signals a few kilohertz away but when RTTY contesting I do seem to notice there may be some desensing or AGC action from these signals even though they are not heard or processed by MMTTY.
>
> Comments very much appreciated.
>
> CU in the Colorado QSO Party Sept 4th, 2010.
>
> 73, Jim, W0EM
>
>
>
> ______________________________________________________________
> 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
>

Eric Swartz - WA6HHQ

Re: K3 SO2R Question

Administrator

All New K3s for some time have had this change made at the factory
before they ship.

73, Eric

On 3/8/2010 4:04 PM, Brett Howard wrote:

> http://www.elecraft.com/K3/mods/K3%20rx%20protection%20mod,%20rev%20B.pdf
>
> That document explains a mod that you should definitely make sure is
> in place in your radio if you're worried about this condition. I had
> one of Q8 and Q9 blow in my radio after too much power came back in
> from another operator who told me he *WAS* staying off of 20 meter
> like to told him to do he was down on 14 meters! ;) Anyway we
> replaced the Q and the rig came back to life. But if you view that
> document it says that when you get to +13 to +20dBm it will
> automatically engage the preamp for you. +20dBm is 100mW so that
> would at least give you an added 10dB of protection on your way up to
> the 1-2W realm.
>
> ~Brett (KC7OTG)
>
>

Igor Sokolov-2

Re: K3 SO2R Question

Starting what serial numbers please.

73, Igor UA9CDC

> All New K3s for some time have had this change made at the factory
> before they ship.
>
> 73, Eric
>
>
> On 3/8/2010 4:04 PM, Brett Howard wrote:
>> http://www.elecraft.com/K3/mods/K3%20rx%20protection%20mod,%20rev%20B.pdf
>>
>> That document explains a mod that you should definitely make sure is
>> in place in your radio if you're worried about this condition. I had
>> one of Q8 and Q9 blow in my radio after too much power came back in
>> from another operator who told me he *WAS* staying off of 20 meter
>> like to told him to do he was down on 14 meters! ;) Anyway we
>> replaced the Q and the rig came back to life. But if you view that
>> document it says that when you get to +13 to +20dBm it will
>> automatically engage the preamp for you. +20dBm is 100mW so that
>> would at least give you an added 10dB of protection on your way up to
>> the 1-2W realm.
>>
>> ~Brett (KC7OTG)
>>
>>
> ______________________________________________________________
> 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

Don Wilhelm-4

Re: K3 SO2R Question

Igor,

Looking at the Elecraft website for K3 Mods and application notes, it
says "*About 09/01/09 (RF board Rev H3) and later."
*The serial number is difficult to track because of the difference
between kit-built and factory assembled K3s. The ship date is the most
significant tracking method for mods that are included.

When in doubt, consult www.elecraft.com.

73,
Don W3FPR

Igor Sokolov wrote:

> Starting what serial numbers please.
>
> 73, Igor UA9CDC
>
>
>> All New K3s for some time have had this change made at the factory
>> before they ship.
>>
>> 73, Eric
>>
>>
>> On 3/8/2010 4:04 PM, Brett Howard wrote:
>>
>>> http://www.elecraft.com/K3/mods/K3%20rx%20protection%20mod,%20rev%20B.pdf
>>>
>>> That document explains a mod that you should definitely make sure is
>>> in place in your radio if you're worried about this condition. I had
>>> one of Q8 and Q9 blow in my radio after too much power came back in
>>> from another operator who told me he *WAS* staying off of 20 meter
>>> like to told him to do he was down on 14 meters! ;) Anyway we
>>> replaced the Q and the rig came back to life. But if you view that
>>> document it says that when you get to +13 to +20dBm it will
>>> automatically engage the preamp for you. +20dBm is 100mW so that
>>> would at least give you an added 10dB of protection on your way up to
>>> the 1-2W realm.
>>>
>>> ~Brett (KC7OTG)
>>>
>>>
>>>
>> ______________________________________________________________
>> 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
>>
>
> ______________________________________________________________
> 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
> ------------------------------------------------------------------------
>
>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 9.0.733 / Virus Database: 271.1.1/2730 - Release Date: 03/08/10 02:34:00
>
>

Igor Sokolov-2

Re: K3 SO2R Question

Thanks Don.

73, Igor UA9CDC

> Igor,
>
> Looking at the Elecraft website for K3 Mods and application notes, it says
> "*About 09/01/09 (RF board Rev H3) and later."
> *The serial number is difficult to track because of the difference between
> kit-built and factory assembled K3s. The ship date is the most
> significant tracking method for mods that are included.
>
> When in doubt, consult www.elecraft.com.
>
> 73,
> Don W3FPR
>
> Igor Sokolov wrote:
>> Starting what serial numbers please.
>>
>> 73, Igor UA9CDC
>>
>>
>>> All New K3s for some time have had this change made at the factory
>>> before they ship.
>>>
>>> 73, Eric
>>>
>>>
>>> On 3/8/2010 4:04 PM, Brett Howard wrote:
>>>
>>>> http://www.elecraft.com/K3/mods/K3%20rx%20protection%20mod,%20rev%20B.pdf
>>>>
>>>> That document explains a mod that you should definitely make sure is
>>>> in place in your radio if you're worried about this condition. I had
>>>> one of Q8 and Q9 blow in my radio after too much power came back in
>>>> from another operator who told me he *WAS* staying off of 20 meter
>>>> like to told him to do he was down on 14 meters! ;) Anyway we
>>>> replaced the Q and the rig came back to life. But if you view that
>>>> document it says that when you get to +13 to +20dBm it will
>>>> automatically engage the preamp for you. +20dBm is 100mW so that
>>>> would at least give you an added 10dB of protection on your way up to
>>>> the 1-2W realm.
>>>>
>>>> ~Brett (KC7OTG)
>>>>
>>>>
>>>>
>>> ______________________________________________________________
>>> 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
>>
>> ______________________________________________________________
>> 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
>> ------------------------------------------------------------------------
>>
>>
>> No virus found in this incoming message.
>> Checked by AVG - www.avg.com Version: 9.0.733 / Virus Database:
>> 271.1.1/2730 - Release Date: 03/08/10 02:34:00
>>
>>

Jim HaRRIS

Re: K3 SO2R Question

In reply to this post by Bob Naumann W5OV

Bob,

I live on a postage size lot so big antennas and lots of separation is not possible. I usually run an ALS-500M amp. My initial thought is to run both K3's on the same bands. However, digging out mult's on different bands might be the way to go. The same band idea came from my days with duel watch radio's. It's all a growing and learning experience.

I've looked at the ICE filters plus those from other companys. I'm guessing at this point the more isolation (expensive) filters would be better. I've discovered in the last day or so that when signal levels are over about S9+30/40 the K3 receiver goes strangely quiet and no bars on the S-meter are light. It takes from a few seconds to a minute or so to recover.

Thank you for your suggestions.

CU in the Colorado QSO Party Sept 4th, 2010.

73, Jim, W0EM

> From: [hidden email]
> To: [hidden email]; [hidden email]
> Subject: RE: [Elecraft] K3 SO2R Question
> Date: Mon, 8 Mar 2010 17:20:49 -0600
>
> Jim,
>
> Are you asking if you can run high power SO2R and do so safely without
> bandpass filters? You didn't mention what power level, and this makes a huge
> difference.
>
> You can use ICE bandpass filters (-30 to -35db) which are relatively cheap
> (~$40 each). Their performance is not as good as W3NQN design filters (-75db
> to -80db) which are the ones that cost big bucks(~$99 each). If you allocate
> one radio to doing say 160, 40 and 15 and the other to doing 80, 20 and 10m,
> you could get by with just one set of 6 bandpass filters.
>
> While bandpass filters have a by-product of protecting your radio's front
> end, that's not all they do. The filter on the transmitter limits what gets
> out and the filter on the receiver limits what gets in - so having a filter
> on each radio increases the benefit. This is more of a practical operational
> thing than being protective.
>
> Also, when you say "separation of frequencies within the band" do you intend
> to run both radios on the same band? Needless to say, bandpass filters will
> not be of any use if you do this. The key here is physical separation of
> your antennas so that the coupling between the two is minimized.
>
> Bob W5OV
>
> P.S. ICE has a new owner and is delivering product again much more quickly.
>
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of Jim Harris
> Sent: Monday, March 08, 2010 4:03 PM
> To: Elecraft Email
> Subject: [Elecraft] K3 SO2R Question
>
>
> Hi Folks,
>
> I'm currently selling an off-shore rig with the hopes of acquiring a second
> K3 for SO2R, primarily for RTTY contesting. I believe I've seen somewhere
> in the not to distant past that is was said the K3 receive front end can
> withstand 1-2 watts without damage. I've spent the last hour reviewing the
> email archive and can find no reference to that. Can anyone confirm or deny
> my remembrance? (Or, is it all just wishful thinking?) Is there anyone on
> the reflector that is operating a K3 SO2R station without the thousand or so
> dollars of band pass filters needed to protect the radio's front end?
>
> Second part of the question is.....if possible to not damage the front end,
> what is the possibility of desensing or causing blocking or noise that would
> interfere with reception on one receiver when transmitting on the other
> radio. I'm sure that is highly dependent on band(s) and separation of
> frequencies within the band. I'll fully aware of the K3's ability to
> completely block signals a few kilohertz away but when RTTY contesting I do
> seem to notice there may be some desensing or AGC action from these signals
> even though they are not heard or processed by MMTTY.
>
> Comments very much appreciated.
>
> CU in the Colorado QSO Party Sept 4th, 2010.
>
> 73, Jim, W0EM
>
>
>
> ______________________________________________________________
> 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
>

Jim HaRRIS

Re: K3 SO2R Question

In reply to this post by Tony Fegan VE3QF

Tony,

Thank you for the link. Those are not the exact words I remember but they contribute to my understanding. I received my K3 in early September 2009 and it has the mod.

CU in the Colorado QSO Party Sept 4th, 2010.

73, Jim, W0EM

> Date: Mon, 8 Mar 2010 18:33:34 -0500
> From: [hidden email]
> To: [hidden email]
> CC: [hidden email]
> Subject: Re: [Elecraft] K3 SO2R Question
>
> Hi Jim,
>
> I think this is the thread you are looking for:
>
> http://n2.nabble.com/KRX3-Overload-Protection-on-160M-td3814157.html#a3814157
>
>
> Hope this helps.
> 73
> Tony Fegan VE3QF
>
>
> Jim Harris wrote:
> > Hi Folks,
> >
> > I'm currently selling an off-shore rig with the hopes of acquiring a
> > second K3 for SO2R, primarily for RTTY contesting. I believe I've
> > seen somewhere in the not to distant past that is was said the K3
> > receive front end can withstand 1-2 watts without damage. I've spent
> > the last hour reviewing the email archive and can find no reference
> > to that. Can anyone confirm or deny my remembrance? (Or, is it all
> > just wishful thinking?) Is there anyone on the reflector that is
> > operating a K3 SO2R station without the thousand or so dollars of
> > band pass filters needed to protect the radio's front end?
> >
> > Second part of the question is.....if possible to not damage the
> > front end, what is the possibility of desensing or causing blocking
> > or noise that would interfere with reception on one receiver when
> > transmitting on the other radio. I'm sure that is highly dependent
> > on band(s) and separation of frequencies within the band. I'll fully
> > aware of the K3's ability to completely block signals a few kilohertz
> > away but when RTTY contesting I do seem to notice there may be some
> > desensing or AGC action from these signals even though they are not
> > heard or processed by MMTTY.
> >
> > Comments very much appreciated.
> >
> > CU in the Colorado QSO Party Sept 4th, 2010.
> >
> > 73, Jim, W0EM
> >
> >
> > ______________________________________________________________
> > 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
> >

Jim HaRRIS

Re: K3 SO2R Question

In reply to this post by Brett Howard

Brett,

Thank you for the link. As I mentioned in a reply to someone else my radio has the mod. In lieu of any definitive statement from Elecraft it probably would be best to go in the safer direction of using filters.

CU in the Colorado QSO Party Sept 4th, 2010.

73, Jim, W0EM

> From: [hidden email]
> Date: Mon, 8 Mar 2010 16:04:28 -0800
> Subject: Re: [Elecraft] K3 SO2R Question
> To: [hidden email]
> CC: [hidden email]
>
> http://www.elecraft.com/K3/mods/K3%20rx%20protection%20mod,%20rev%20B.pdf
>
> That document explains a mod that you should definitely make sure is
> in place in your radio if you're worried about this condition. I had
> one of Q8 and Q9 blow in my radio after too much power came back in
> from another operator who told me he *WAS* staying off of 20 meter
> like to told him to do he was down on 14 meters! ;) Anyway we
> replaced the Q and the rig came back to life. But if you view that
> document it says that when you get to +13 to +20dBm it will
> automatically engage the preamp for you. +20dBm is 100mW so that
> would at least give you an added 10dB of protection on your way up to
> the 1-2W realm.
>
> ~Brett (KC7OTG)
>
> On Mon, Mar 8, 2010 at 2:03 PM, Jim Harris <[hidden email]> wrote:
> >
> > Hi Folks,
> >
> > I'm currently selling an off-shore rig with the hopes of acquiring a second K3 for SO2R, primarily for RTTY contesting. I believe I've seen somewhere in the not to distant past that is was said the K3 receive front end can withstand 1-2 watts without damage. I've spent the last hour reviewing the email archive and can find no reference to that. Can anyone confirm or deny my remembrance? (Or, is it all just wishful thinking?) Is there anyone on the reflector that is operating a K3 SO2R station without the thousand or so dollars of band pass filters needed to protect the radio's front end?
> >
> > Second part of the question is.....if possible to not damage the front end, what is the possibility of desensing or causing blocking or noise that would interfere with reception on one receiver when transmitting on the other radio. I'm sure that is highly dependent on band(s) and separation of frequencies within the band. I'll fully aware of the K3's ability to completely block signals a few kilohertz away but when RTTY contesting I do seem to notice there may be some desensing or AGC action from these signals even though they are not heard or processed by MMTTY.
> >
> > Comments very much appreciated.
> >
> > CU in the Colorado QSO Party Sept 4th, 2010.
> >
> > 73, Jim, W0EM
> >
> >
> >
> > ______________________________________________________________
> > 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
> >

Re: K3 SO2R Question

In reply to this post by Jim HaRRIS

Jim, for single band operation the sub-receiver works very well and does not need additional filters. If you find a mult on the sub, just stop your CQ, tap A/B, make your call, then tap A/B and go back to CQ. You don't need another K3 on the same band for that.
Willis 'Cookie' Cooke
K5EWJ

________________________________
From: Jim Harris <[hidden email]>
To: [hidden email]; Elecraft Email <[hidden email]>
Sent: Tue, March 9, 2010 11:08:42 AM
Subject: Re: [Elecraft] K3 SO2R Question

Bob,

I live on a postage size lot so big antennas and lots of separation is not possible. I usually run an ALS-500M amp. My initial thought is to run both K3's on the same bands. However, digging out mult's on different bands might be the way to go. The same band idea came from my days with duel watch radio's. It's all a growing and learning experience.

I've looked at the ICE filters plus those from other companys. I'm guessing at this point the more isolation (expensive) filters would be better. I've discovered in the last day or so that when signal levels are over about S9+30/40 the K3 receiver goes strangely quiet and no bars on the S-meter are light. It takes from a few seconds to a minute or so to recover.

Thank you for your suggestions.

CU in the Colorado QSO Party Sept 4th, 2010.

73, Jim, W0EM

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K5WA

Re: K3 SO2R Question

In reply to this post by Jim HaRRIS

Jim,

As a long time SO2R guy (currently a pair of K3s, previously a pair of K2s
and originally a pair of IC-765s), I'd save up your money and get the ICE
(individual bands or the 401 multiband unit) or K3NQN filters so you won't
be saying things like "the K3 receiver goes strangely quiet". Those words
scare the fire out of me because I'll bet you are on the edge of blowing up
your K3's front end. While you are saving up your money, you can build some
coax filters that can be teed into your monoband coax (the complexity and
expense goes up if you have a multi-band antenna rather than monobander).
I'd have to look up the exact construction details, but I know they can be
found with minimal Google searching. The idea is to cut a length of coax
that, for example, nulls 20M (electrical 1/4 wave open at the end, I think?)
and insert that into your 40M line. Same idea for keeping 80M out of 40M.
You really don't want to be asking how much power the K3 receiver can
handle...just assume it is 50-100 mV and build or buy some filters. You'll
be happily SO2R contesting rather than repairing your K3s. I have used the
ICE 401 multiband units for several years and have been very happy even when
my antenna system consisted of individually fed multi-quad loops. Imagine
happily SO2R contesting at 1.5 KW with quad loops only separated by a few
feet. Filters work!

Also, save up your money and get the KRX3 for your K3s if you want to have
"dual watch" because you will have defeated every SO2R control box and
software program I know of if both SO2R rigs are on the same band.

Have fun!

Bob K5WA

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Message: 1

Date: Tue, 9 Mar 2010 17:08:42 +0000

From: Jim Harris <[hidden email]>

Subject: Re: [Elecraft] K3 SO2R Question

Bob,

I live on a postage size lot so big antennas and lots of separation is not
possible. I usually run an ALS-500M amp. My initial thought is to run both
K3's on the same bands. However, digging out mult's on different bands
might be the way to go. The same band idea came from my days with duel
watch radio's. It's all a growing and learning experience.

I've looked at the ICE filters plus those from other companys. I'm guessing
at this point the more isolation (expensive) filters would be better. I've
discovered in the last day or so that when signal levels are over about
S9+30/40 the K3 receiver goes strangely quiet and no bars on the S-meter are
light. It takes from a few seconds to a minute or so to recover.

Thank you for your suggestions.

CU in the Colorado QSO Party Sept 4th, 2010.

73, Jim, W0EM

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K5WA

Re: K3 SO2R Question

In reply to this post by Jim HaRRIS

Jim,

As a follow up to my post about coax stubs yesterday, Dick, K6KR sent me the
Inrad link below in case you want to buy a book to help you through SO2R
interference. I also did some Googling and found a VERY good and concise
description of the coax stub filters and their implementation in an
automated environment at Top Ten Devices. You could take the filter
information and build coax stubs for a manual implementation if you didn't
want to use the automation components. Both sources are from W2VJN, George
Cutsogeorge, and should help you get to where you want to be with your SO2R
station so you don't blow out the front end of your K3s.

http://www.qth.com/topten/apnote2.htm

http://www.inrad.net/product.php?productid=248
<http://www.inrad.net/product.php?productid=248&cat=148&page=1>
&cat=148&page=1

73,

Bob K5WA

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