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

[Walter Underwood]

Did the KX3 have the isolation preamp turned on? It is normal for a direct conversion receiver to leak the LO at the operating frequency. The KX3 has a special preamp that prevents that.

Also, antennas 20 feet apart might as well have coax directly from the transmitter into the receiver. That will cause huge coupling of TX into RX. Running 500W and 1.5kW? You are lucky that the receivers survived, let alone were able to work any band when the other one was transmitting.

Don’t do that again.

wunder
K6WRU
CM87wj
http://observer.wunderwood.org/ (my blog)

On Jul 1, 2015, at 9:33 PM, Matt Z via Elecraft <elecraft at mailman.qth.net> 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.
> 
> Date: Wed, 1 Jul 2015 12:43:16 -0400From: Guy Olinger K2AV <k2av.guy at gmail.com>To: N1EU <n1eu.barry at gmail.com>Cc: Elecraft Reflector <elecraft at mailman.qth.net>Subject: Re: [Elecraft] K3 FD report in high RF (K3 vs Flex 6xxx)Message-ID:    <CANckpc1sUaYtmRtJLJn0KBdYZaY+-gACJqqUWBKGVM0VxSPjNw at mail.gmail.com>Content-Type: text/plain; charset=UTF-8
> On Wed, Jul 1, 2015 at 8:34 AM, N1EU <n1eu.barry at 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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