K3 FD report in high RF (K3 vs Flex 6xxx)

[Elecraft mailing list]

KL7AA had two elecrafts at FD, a KX3 for SSB and a K3 for CW, and interference was a definitely noticed.  Each rig was wired to separate 3 element stepIRs, about 20 feet apart.  One rig used the elecraft 500w amp and one used a 1.5kw amp.  The two elecrafts could not operate on the same band at all.  Maybe it was something with the setup.

Date: Wed, 1 Jul 2015 12:43:16 -0400From: Guy Olinger K2AV <[hidden email]>To: N1EU <[hidden email]>Cc: Elecraft Reflector <[hidden email]>Subject: Re: [Elecraft] K3 FD report in high RF (K3 vs Flex 6xxx)Message-ID:    <[hidden email]>Content-Type: text/plain; charset=UTF-8
On Wed, Jul 1, 2015 at 8:34 AM, N1EU <[hidden email]> wrote:
> The Flex ops should have dialed in a little front-end attenuation to> alleviate the ADC overload problem.>
Understand the sentiment, but more attenuation is operationallycontra-indicated if the signals you're trying to work are weak due totemporary emergency antennas and QRP.
Part of emergency preparedness is understanding various rigsnon-prejudicially for their various strengths and weaknesses and choosingrigs for strengths and avoiding rigs for weakness as those apply to thespecifics of an application.
These days weak signals and close multiple transceivers call for the likesof K3's.
At N4C field day we frequently had a CW station and SSB station on the sameband with no interference, and actually without being aware of each other.No noise, no anything. I know what a K3's hardware AGC kick-in sounds likeand that was also absent. This has been our experience for five or sixfield days now, and together with the small light size and portability,makes the K3 a top pick for FD. Not because of Koolaid, but because ofproven suitability to the application.
I'm waiting to hear about KX3's for FD, especially battery operation, longa specific niche for K2's.
We did not have a K3S or K3 with KSYN3A for evaluation. We have a standingquestion of whether K3S/upgraded K3, with some horizontal separation, willbe able to operate a few KHz away from each other on the same band/modesegment, e.g. the 40 CW station, and the GOTA station on 40 CW at the sametime. Perhaps next year we will find out.
N4C operated at the Grey Goose Farm near Creedmore, NC. The group was alarge portion of the North Carolina East chapter of the Potomac ValleyRadio Club. This group contains a significant supply of K3 owners, whoregularly bring K3's to FD and multi-op contest events. For themportability and immunity to high RF environments are top-of-the-listreasons for purchasing K3's as opposed to other choices, easily serving FDstyle applications.
At NY4A, also primarily manned by PVRC NC East members, going back pre-K3the FT1000MP was the main rig, which had gradually replaced all thestalwart Japanese rigs of prior years. For some time the MP was the onlyrig seen there. When the K3's and other rigs with new generation RX cameout, and the differences became known, The MP's were gradually replaced. Atally of the list of MP owning operators who had manned NY4A at some pointindicated that 11 MP's had been replaced by 14 K3's and one Orion. Of thatgroup, no one owns a Flex to this date. But neither would I consider any ofthem to be a "Flex-basher".
I do know Flex owners, single home stations, who get outstandingperformance away from high-RF multi-TX operations. Various problems with CWand spectral purity seem to be a continuing manufacturer's emphasis forsolution. They're out there on a particular bleeding edge, with aparticular emphasis, with its own set of problems. We'll just see what theydo. Bashing not necessary.
UPS currently has my 2015 K3 upgrade round: KXV3B, KSYN3A's, a second KBPF3(A version) and finally a P3 and P3SVGA. I will get the new audio boardwhen it's available.
Regards All,
Guy K2AV
 
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[Jim Brown-10]

On Wed,7/1/2015 9:33 PM, Matt Z via Elecraft wrote:
> KL7AA had two elecrafts at FD, a KX3 for SSB and a K3 for CW, and interference was a definitely noticed.  Each rig was wired to separate 3 element stepIRs, about 20 feet apart.  One rig used the elecraft 500w amp and one used a 1.5kw amp.  The two elecrafts could not operate on the same band at all.  Maybe it was something with the setup.

Your expectations are unreasonable -- 20 ft is WAY too close, even for
two great rigs on the same band at 500W.  We run K3s to KPA500s on the
same band for CQP (Cal QSO Party) county expeditions and use 250 ft
spacing with antennas carefully located to be essentially colinear. 150
ft is not enough.

73, Jim K9YC
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[David Gilbert]

"Maybe it was something with the setup."

That's an understatement.

Running kilowatt-level power on the same band to two antennas only 20
feet apart is simply crazy.   I don't know what input protection the
KX3's have, but they almost certainly kicked in and being inherently
non-linear they would have generated all sorts of high level trash on
the front end.  It would be interesting to see the math, but I think
you're lucky you didn't blow the heck out of both front ends in spite of
the protection.

Dave   AB7E




On Jul 1, 2015, at 9:33 PM, Matt Z via Elecraft <[hidden email]> wrote:

> KL7AA had two elecrafts at FD, a KX3 for SSB and a K3 for CW, and interference was a definitely noticed.  Each rig was wired to separate 3 element stepIRs, about 20 feet apart.  One rig used the elecraft 500w amp and one used a 1.5kw amp.  The two elecrafts could not operate on the same band at all.  Maybe it was something with the setup.

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[Elecraft mailing list]

with that sort of power level, you are looking at several devices failing, and making the system deaf as a post.

 KK4QDZ - Now with Extra Class Priv's, and a tiny KX3 to enjoy them!
      From: David Gilbert <[hidden email]>
 To: [hidden email]
 Sent: Thursday, July 2, 2015 3:46 AM
 Subject: Re: [Elecraft] K3 FD report in high RF (K3 vs Flex 6xxx)
   

"Maybe it was something with the setup."

That's an understatement.

Running kilowatt-level power on the same band to two antennas only 20
feet apart is simply crazy.  I don't know what input protection the
KX3's have, but they almost certainly kicked in and being inherently
non-linear they would have generated all sorts of high level trash on
the front end.  It would be interesting to see the math, but I think
you're lucky you didn't blow the heck out of both front ends in spite of
the protection.

Dave  AB7E






On Jul 1, 2015, at 9:33 PM, Matt Z via Elecraft <[hidden email]> wrote:

> KL7AA had two elecrafts at FD, a KX3 for SSB and a K3 for CW, and interference was a definitely noticed.  Each rig was wired to separate 3 element stepIRs, about 20 feet apart.  One rig used the elecraft 500w amp and one used a 1.5kw amp.  The two elecrafts could not operate on the same band at all.  Maybe it was something with the setup.

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[David Olean]

Hello Matt,
Wow, with those power levels and a 20 ft spacing between 3 el yagis, you are
"cruisin' for a bruisin'". I made some measurements at my home station with
two K3s on ten meters feeding different antennas. The antennas were 300 ft
apart.  I aligned the two yagis to face each other and saw only 17 dB of
isolation. One of my K3's was hooked to a 1500 watt amp. With the antennas
aimed at each other, there would be 30 watts coming down the feedline of K3
#2! Now my yagis were bigger than 3 elements: I had 5 and 6 element HB
beams, but the problem is lack of isolation between any directional antenna.
A few dB makes little difference.
    I still have not solved the in band overload problem entirely. 1500
watts is a lot of power. Cross polarization is a good way to go. Make one
antenna vertically polarized and pick up a bit over 20 dB. The other
technique is to avoid aiming antennas in directions that aggravate the
problem. I think you would want 60 dB of rig to rig isolation with a legal
limit amplifier for really good results.  Having antennas at differing
heights, cross polarized, and widely separated, can get you close, but I am
afraid that boresighted antennas will still cause problems at 1500 watts.
QRP looks better and better!!

Dave K1WHS
----- Original Message -----
From: "Matt Z via Elecraft" <[hidden email]>
To: <[hidden email]>
Sent: Thursday, July 02, 2015 4:33 AM
Subject: [Elecraft] K3 FD report in high RF (K3 vs Flex 6xxx)

> KL7AA had two elecrafts at FD, a KX3 for SSB and a K3 for CW, and
> interference was a definitely noticed. Each rig was wired to separate 3
> element stepIRs, about 20 feet apart. One rig used the elecraft 500w amp
> and one used a 1.5kw amp. The two elecrafts could not operate on the same
> band at all. Maybe it was something with the setup.
>
> Date: Wed, 1 Jul 2015 12:43:16 -0400From: Guy Olinger K2AV
> <[hidden email]>To: N1EU <[hidden email]>Cc: Elecraft Reflector
> <[hidden email]>Subject: Re: [Elecraft] K3 FD report in high RF
> (K3 vs Flex 6xxx)Message-ID:
> <[hidden email]>Content-Type:
> text/plain; charset=UTF-8
> On Wed, Jul 1, 2015 at 8:34 AM, N1EU <[hidden email]> wrote:
>> The Flex ops should have dialed in a little front-end attenuation to>
>> alleviate the ADC overload problem.>
> Understand the sentiment, but more attenuation is
> operationallycontra-indicated if the signals you're trying to work are
> weak due totemporary emergency antennas and QRP.
> Part of emergency preparedness is understanding various
> rigsnon-prejudicially for their various strengths and weaknesses and
> choosingrigs for strengths and avoiding rigs for weakness as those apply
> to thespecifics of an application.
> These days weak signals and close multiple transceivers call for the
> likesof K3's.
> At N4C field day we frequently had a CW station and SSB station on the
> sameband with no interference, and actually without being aware of each
> other.No noise, no anything. I know what a K3's hardware AGC kick-in
> sounds likeand that was also absent. This has been our experience for five
> or sixfield days now, and together with the small light size and
> portability,makes the K3 a top pick for FD. Not because of Koolaid, but
> because ofproven suitability to the application.
> I'm waiting to hear about KX3's for FD, especially battery operation,
> longa specific niche for K2's.
> We did not have a K3S or K3 with KSYN3A for evaluation. We have a
> standingquestion of whether K3S/upgraded K3, with some horizontal
> separation, willbe able to operate a few KHz away from each other on the
> same band/modesegment, e.g. the 40 CW station, and the GOTA station on 40
> CW at the sametime. Perhaps next year we will find out.
> N4C operated at the Grey Goose Farm near Creedmore, NC. The group was
> alarge portion of the North Carolina East chapter of the Potomac
> ValleyRadio Club. This group contains a significant supply of K3 owners,
> whoregularly bring K3's to FD and multi-op contest events. For
> themportability and immunity to high RF environments are
> top-of-the-listreasons for purchasing K3's as opposed to other choices,
> easily serving FDstyle applications.
> At NY4A, also primarily manned by PVRC NC East members, going back
> pre-K3the FT1000MP was the main rig, which had gradually replaced all
> thestalwart Japanese rigs of prior years. For some time the MP was the
> onlyrig seen there. When the K3's and other rigs with new generation RX
> cameout, and the differences became known, The MP's were gradually
> replaced. Atally of the list of MP owning operators who had manned NY4A at
> some pointindicated that 11 MP's had been replaced by 14 K3's and one
> Orion. Of thatgroup, no one owns a Flex to this date. But neither would I
> consider any ofthem to be a "Flex-basher".
> I do know Flex owners, single home stations, who get
> outstandingperformance away from high-RF multi-TX operations. Various
> problems with CWand spectral purity seem to be a continuing manufacturer's
> emphasis forsolution. They're out there on a particular bleeding edge,
> with aparticular emphasis, with its own set of problems. We'll just see
> what theydo. Bashing not necessary.
> UPS currently has my 2015 K3 upgrade round: KXV3B, KSYN3A's, a second
> KBPF3(A version) and finally a P3 and P3SVGA. I will get the new audio
> boardwhen it's available.
> Regards All,
> Guy K2AV
>
> ______________________________________________________________
> 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
> Message delivered to [hidden email]

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[Greg Troxel-2]

Jim Brown <[hidden email]> writes:

> Your expectations are unreasonable -- 20 ft is WAY too close, even for
> two great rigs on the same band at 500W.  We run K3s to KPA500s on the
> same band for CQP (Cal QSO Party) county expeditions and use 250 ft
> spacing with antennas carefully located to be essentially
> colinear. 150 ft is not enough.

I was at a FD site where we had significant interstation interference,
and I think it was a combination of just too close and a dirty
transmitter (IC7200), with the other station being a K3 with new synths.
We didn't measure the antenna coupling, and I made a mental note to do
that next time.  What we had was

  40m 2-el wire beam
  20/15/10 wire beam

  G5RV

The two beams had ends separated by only a few meters, but were almost
collinear.  The G5RV was parallel (in a bad way) about 30m away, but on
the back side of the beams.
Our troubles seemed worst on 20m.   I know the spacing is not
reasonable; past FDs at the same site/club had used KX3s or K2s QRP, and
things were mostly ok then.

So, I wonder:

  When you used the 250 ft spacing (and in the nulls), what kind of
  measured coupling did you see?

  What would people expect for power loss between the G5RV and the beam?
  Based on other comments, distance, and the beam heading the wrong way,
  I'd guess about 50 dB.


I guess another question is, given a pair of K3-newsynth transceivers,
what level of antenna isolation is necessary to bring the wideband noise
from reciprocal mixing and transmit noise down to say the S1 level?

Assume S1 is -121 dBm (from -73 and 8 units).  Or really lets say that's
the level we care about.  TX at 100W is +50 dBm.  If one uses -128 dBC
for transmit noise, and assumes some improvement from the 108 dB of RMDR
(taking the average of ARRL/sherweng) at perhaps 118 dB, then we need 53
dB of isolation.

The IC-7200 has transmit noise at -94 dBC, so I'd expect 24 dB worse,
which is S5 noise instead of S1 imposed on a perfect other receiver.

I am curious if my math is confused, and how real measurements and
experiences compare.  It seems that reviews should set up 2 of the radio
under test with controlled isolation and see how in-band artifacts are.
And also test against a K3s both ways.

73 de n1dam
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[Joe Subich, W4TV-4]

 > What would people expect for power loss between the G5RV and the
 > beam?  Based on other comments, distance, and the beam heading the
 > wrong way, I'd guess about 50 dB.

50 dB is probably optimistic.  The equation for free space path loss
(coupling between antennas) is -40 dB + antenna gain - a wavelength
dependent factor.  However, that only holds in the far field (30m is
near field for anything below 144 MHz).

My hunch is that the isolation between two resonant antennas in
the near field will be something less than 30 dB unless they are
[reasonably] collinear.

73,

   ... Joe, W4TV


On 2015-07-03 10:03 AM, Greg Troxel wrote:

> Jim Brown <[hidden email]> writes:
>
>> Your expectations are unreasonable -- 20 ft is WAY too close, even for
>> two great rigs on the same band at 500W.  We run K3s to KPA500s on the
>> same band for CQP (Cal QSO Party) county expeditions and use 250 ft
>> spacing with antennas carefully located to be essentially
>> colinear. 150 ft is not enough.
>
> I was at a FD site where we had significant interstation interference,
> and I think it was a combination of just too close and a dirty
> transmitter (IC7200), with the other station being a K3 with new synths.
> We didn't measure the antenna coupling, and I made a mental note to do
> that next time.  What we had was
>
>    40m 2-el wire beam
>    20/15/10 wire beam
>
>    G5RV
>
> The two beams had ends separated by only a few meters, but were almost
> collinear.  The G5RV was parallel (in a bad way) about 30m away, but on
> the back side of the beams.
> Our troubles seemed worst on 20m.   I know the spacing is not
> reasonable; past FDs at the same site/club had used KX3s or K2s QRP, and
> things were mostly ok then.
>
> So, I wonder:
>
>    When you used the 250 ft spacing (and in the nulls), what kind of
>    measured coupling did you see?
>
>    What would people expect for power loss between the G5RV and the beam?
>    Based on other comments, distance, and the beam heading the wrong way,
>    I'd guess about 50 dB.
>
>
> I guess another question is, given a pair of K3-newsynth transceivers,
> what level of antenna isolation is necessary to bring the wideband noise
> from reciprocal mixing and transmit noise down to say the S1 level?
>
> Assume S1 is -121 dBm (from -73 and 8 units).  Or really lets say that's
> the level we care about.  TX at 100W is +50 dBm.  If one uses -128 dBC
> for transmit noise, and assumes some improvement from the 108 dB of RMDR
> (taking the average of ARRL/sherweng) at perhaps 118 dB, then we need 53
> dB of isolation.
>
> The IC-7200 has transmit noise at -94 dBC, so I'd expect 24 dB worse,
> which is S5 noise instead of S1 imposed on a perfect other receiver.
>
> I am curious if my math is confused, and how real measurements and
> experiences compare.  It seems that reviews should set up 2 of the radio
> under test with controlled isolation and see how in-band artifacts are.
> And also test against a K3s both ways.
>
> 73 de n1dam
> ______________________________________________________________
> 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
> Message delivered to [hidden email]
>

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[Dr. William J. Schmidt, II]

Yes 50dB is about 30dB too high...  Simple modelling says it all...


Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

Owner - Operator
Big Signal Ranch - K9ZC
Staunton, Illinois

Owner - Operator
Villa Grand Piton - J68HZ
Soufriere, St. Lucia W.I.
Rent it: www.VillaGrandPiton.com

email:  [hidden email]

-----Original Message-----
From: Elecraft [mailto:[hidden email]] On Behalf Of Joe
Subich, W4TV
Sent: Friday, July 03, 2015 9:21 AM
To: [hidden email]
Subject: Re: [Elecraft] K3 FD report in high RF (K3 vs Flex 6xxx)


 > What would people expect for power loss between the G5RV and the
 > beam?  Based on other comments, distance, and the beam heading the
 > wrong way, I'd guess about 50 dB.

50 dB is probably optimistic.  The equation for free space path loss
(coupling between antennas) is -40 dB + antenna gain - a wavelength
dependent factor.  However, that only holds in the far field (30m is
near field for anything below 144 MHz).

My hunch is that the isolation between two resonant antennas in
the near field will be something less than 30 dB unless they are
[reasonably] collinear.

73,

   ... Joe, W4TV


On 2015-07-03 10:03 AM, Greg Troxel wrote:

> Jim Brown <[hidden email]> writes:
>
>> Your expectations are unreasonable -- 20 ft is WAY too close, even for
>> two great rigs on the same band at 500W.  We run K3s to KPA500s on the
>> same band for CQP (Cal QSO Party) county expeditions and use 250 ft
>> spacing with antennas carefully located to be essentially
>> colinear. 150 ft is not enough.
>
> I was at a FD site where we had significant interstation interference,
> and I think it was a combination of just too close and a dirty
> transmitter (IC7200), with the other station being a K3 with new synths.
> We didn't measure the antenna coupling, and I made a mental note to do
> that next time.  What we had was
>
>    40m 2-el wire beam
>    20/15/10 wire beam
>
>    G5RV
>
> The two beams had ends separated by only a few meters, but were almost
> collinear.  The G5RV was parallel (in a bad way) about 30m away, but on
> the back side of the beams.
> Our troubles seemed worst on 20m.   I know the spacing is not
> reasonable; past FDs at the same site/club had used KX3s or K2s QRP, and
> things were mostly ok then.
>
> So, I wonder:
>
>    When you used the 250 ft spacing (and in the nulls), what kind of
>    measured coupling did you see?
>
>    What would people expect for power loss between the G5RV and the beam?
>    Based on other comments, distance, and the beam heading the wrong way,
>    I'd guess about 50 dB.
>
>
> I guess another question is, given a pair of K3-newsynth transceivers,
> what level of antenna isolation is necessary to bring the wideband noise
> from reciprocal mixing and transmit noise down to say the S1 level?
>
> Assume S1 is -121 dBm (from -73 and 8 units).  Or really lets say that's
> the level we care about.  TX at 100W is +50 dBm.  If one uses -128 dBC
> for transmit noise, and assumes some improvement from the 108 dB of RMDR
> (taking the average of ARRL/sherweng) at perhaps 118 dB, then we need 53
> dB of isolation.
>
> The IC-7200 has transmit noise at -94 dBC, so I'd expect 24 dB worse,
> which is S5 noise instead of S1 imposed on a perfect other receiver.
>
> I am curious if my math is confused, and how real measurements and
> experiences compare.  It seems that reviews should set up 2 of the radio
> under test with controlled isolation and see how in-band artifacts are.
> And also test against a K3s both ways.
>
> 73 de n1dam
> ______________________________________________________________
> 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
> Message delivered to [hidden email]
>

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[Gary Smith-2]

I'm thinking this was a late "April fools" gotcha.

73,

Gary
KA1J

>
> On Jul 1, 2015, at 9:33 PM, Matt Z via Elecraft <[hidden email]> wrote:
>
> > KL7AA had two elecrafts at FD, a KX3 for SSB and a K3 for CW, and interference was a definitely noticed.  Each rig was wired to separate 3 element stepIRs, about 20 feet apart.  One rig used the elecraft 500w amp and one used a 1.5kw amp.  The two elecrafts could not operate on the same band at all.  Maybe it was something with the setup.


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[Jim Brown-10]

On Fri,7/3/2015 7:03 AM, Greg Troxel wrote:
> So, I wonder:
>
>    When you used the 250 ft spacing (and in the nulls), what kind of
>    measured coupling did you see?

We never measured anything. Rather, we followed "good engineering
practice," worked to find locations on our site where the antennas could
be colinear and in each others nulls, and as widely separated as
practical.  We used resonant dipoles for 80 and 40, tribanders for
20-10. All had serious ferrite chokes at their feedpoint, all were fed
with big coax (RG213, RG11), all Amphenol connectors, carefully
tightened. Rigs were K3s with KPA500 amps. We also use bandpass filters
on each rig, which helps with harmonics. The result was that we could
have both CW and SSB on the same band.

>    What would people expect for power loss between the G5RV and the beam?
>    Based on other comments, distance, and the beam heading the wrong way,
>    I'd guess about 50 dB.

First, dump the G5RV and use resonant dipoles with serious ferrite
chokes. The chokes are probably good for 3-6 dB additional isolation,
maybe more. Without them, common mode radiation from the feedline fills
in the nulls of the pattern. Second, pay careful attention to all the
little stuff, like the quality of the coax and the connectors, any
switches that are in the way. When you're trying to get 50 dB down, that
little stuff can make or break you.

Note that our high power operation was for the California QSO Party. I
don't consider FD a high power contest -- I've never run more than 100W,
and for the last five years I've been doing it QRP.

73, Jim K9YC

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