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" <elecraft@mailman.qth.net>
To: <elecraft@mailman.qth.net>
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
<k2av....@gmail.com>To: N1EU <n1eu.ba...@gmail.com>Cc: Elecraft Reflector
<elecraft@mailman.qth.net>Subject: Re: [Elecraft] K3 FD report in high RF
(K3 vs Flex 6xxx)Message-ID:
<canckpc1suaytmrtjljn0kbdyzay+-gacjqquwbkgvm0vxsp...@mail.gmail.com>Content-Type:
text/plain; charset=UTF-8
On Wed, Jul 1, 2015 at 8:34 AM, N1EU <n1eu.ba...@gmail.com> 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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