Hello Samir
I was the one who did the review of the XV144 in QST. But I am NOT
responsible for the technical data which was generated by the ARRL lab.
I used the XV144 with an FT1000MP as an IF strip. I was impressed with the
performance of the XV144. I tested it against two very loud locals who run
1.5 kw to 5 wavelength yagis, one 14 km away and the other about 40 km away
at 350 meters high but line of sight to the top of my tower. Both of these
stations essentially destroy 2 meters with a multimode transceiver. The
XV144 handled both very well - even weak signals could be copied 10 KHz
away. I did an A/B test with the latest version DEMI transceiver and could
not notice any difference in performance. I did get a chance to use the
XV144 in real conditions in a ~ 1 hour E skip opening. Lots of very strong
signals both local and skip. It was like tuning around 10 meters on a wide
open band - a real pleasure.
The following year I tested the new 50 watt DEMI transverter [144-28HP I
think]. It also worked equally well as the XV144. It passed my stong local
signals tests and also sounded very good during an E skip opening [I want to
test more transverters on 2 meters during the summer!].
To address Duane's question about thermal stability, the XV144 did well but
not perfectly. I did lose about 5 watts output to thermal drift 25 watts
down to 20 watts after the heat sink was fully heated, but the settings were
such that I could go for 25 watts cold and 20 watts warm and there was no
problem. The heat sink was quite warm but not overly so in my opinion. So it
is o.k. for SSB but I wasn't able to test it on JT65. Likely the newest DEMI
transverters with their increased filtering perform somewhat better than the
old ones but the differences are not particularly noticable. We have used
both older and newer ones at K8GP for years with very good success. We use
TS850's as IF strips which the article shows do pretty well for an older
receiver that is quite cheap to buy [an important factor for the Grid
Pirates who usually have very little money as a group].
I know some knowledgable people who have tested the K2 with laboratory
equipment. I think there may be some problem with the measurements of phase
noise in the DF9IC website article. The article says that the phase noise
floor does NOT fall off very much with increasing frequency offset. That is
NOT correct unless there is something wrong with the particular K2 they
tested [not likely because they tested 2 different ones]. I don't know why
the measurements in this article are not the same.
Bottom line - although I have not tried that particular combination I would
think that the K2/XV144 would be an excellent choice for 2 meters.
73 Gene W3ZZ
----- Original Message -----
From: <samir.popaja@telia.com>
To: <vhfcontesting@contesting.com>
Sent: Monday, December 11, 2006 7:44 AM
Subject: Re: [VHFcontesting] Elecraft XV144 QST Review Online
> Hello,
>
> Taken from, the http://www.df9ic.de/tech/trxtest/trxtest.html
>
>
> "The Elecraft K2 also has a low IF design using conventional VCOs which
> should
> result in a good LO noise supression but does not. You may compare the
> ARRL
> test results of the LO noise that Elecraft publishes on their own website
> and
> which is closely within our blocking test result (our measured -95 dB RX
> blocking in 20 kHz offset is equivalent to -129 dBc/Hz LO noise). The high
> level of TX noise shows that there seem to be design flaws choosing too
> low
> signal levels internally. The AGC threshold is ridiculously high
> (subjective
> impression). I also do not understand why it uses low quality ladder
> crystal
> filters instead of a filter from monolithic duals like any other radio
> does.
> Overall it was the worst HF radio in the test (OK, a 144 MHz IC910H is
> still
> worse...)."
>
> Is the K2 + XV144 really bad combo or the others transverters are much
> better?
>
>
>
> 73' SM7VZX
>
>
>
> Re: [VHFcontesting] Elecraft XV144 QST Review Online
> from [Duane Grotophorst] [Permanent Link][Original]
>
> To: vhfcontesting@contesting.com
> Subject: Re: [VHFcontesting] Elecraft XV144 QST Review Online
> From: Duane Grotophorst <n9dg@yahoo.com>
> Date: Wed, 1 Sep 2004 18:11:53 -0700 (PDT)
> List-post: <mailto:vhfcontesting@contesting.com>
>
> --- "Kenneth E. Harker" <kenharker@kenharker.com>
> wrote:
>
>> The closest ARRL product review match of a DEMI
>> transverter is the DEMI 50-28CK
>> (http://www.arrl.org/members-
>> only/prodrev/pdf/pr9702.pdf)
>> from 1997. The ARRL has never reviewed the DEMI
>> 144-28CK. This review was pretty harsh, as the
>> transverter as designed required
>> significant external filtering to meet FCC transmit
>> spectral purity requirements, which also adversely
>> affected the receiver performance.
>
> I really wish that the ARRL would do another review of
> the current generation 50-28CK along with its higher
> band siblings. The current 50-28CK being offered by
> DEMI is a VERY different animal than the one that was
> reviewed in 1997. In fact it was just few months after
> that review that current design configuration was
> brought to market by DEMI. Additionally there have
> been number of further incremental enhancements to
> that design since that late 1997 50-28CK version as
> well.
>
> The 1997 ARRL review of the 50-28CK was with the old
> "square boxed" version, the newer rectangular (~5 x
> 7.5 inch) boxed units do have the filtering that was
> lacking in the unit reviewed by the ARRL. I have to
> believe that that change made a big difference in
> performance.
>
> The main curiosity I have with the Elecraft
> transverters is how well they hold up thermally? It
> just doesn't look like there is enough heatsink on
> them for the high duty cycle modes or contesting.
>
> It definitely would be interesting to see all of the
> current generation transverters measured performance
> specifications next to each other. All of these
> measurements done in a lab testing configuration that
> uses the same IF radio to minimize the number of
> environmental and configuration variables.
>
> Duane
> N9DG
> EN53bj
>
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>
>
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