Tranverter performance af K2 in IARU VHF/SHF Contest

[Norbert Roedel]

My qth is very exposed on a hilltop in Bavaria – in the last years I’ve had
big problems with “big guns” next to me. All of them are driving the in
Germany legal power of 750 Watts on 144MHz and all of them (4 Stations) are
in in maximum distance of 10 miles. In the past I was not able to work weak
stations – this year I used the K2 as exciter and a high performance
transverter TR144H from DB6NT ( www.db6nt.de ) . The result was
unbelievable: round about 20kHz away from the stations I was able to work
weakest stations and also the other stations where not disturbed by my
signal – also 750watts hf. The high performance of Michael, DB6NT’s,
transverter has a noise figure of 0.4 – so no special preamp was needed. The
blocking behavior of K2 did the other part of the contest. I’m very very
satisfied by my rig now! I installed the transverter option few days ago and
the transverter worked great with no additional mods. Absolute outstanding
performance!
    

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[Irelands Satellite]

I wonder how the DB6 unit compares with the XV144 in terms of performance?

Thanks
Tony Ei7BMB


At 09:18 06/03/2005, Norbert Roedel wrote:

>My qth is very exposed on a hilltop in Bavaria ­ in the last years I’ve had
>big problems with “big guns” next to me. All of them are driving the in
>Germany legal power of 750 Watts on 144MHz and all of them (4 Stations) are
>in in maximum distance of 10 miles. In the past I was not able to work weak
>stations ­ this year I used the K2 as exciter and a high performance
>transverter TR144H from DB6NT ( www.db6nt.de ) . The result was
>unbelievable: round about 20kHz away from the stations I was able to work
>weakest stations and also the other stations where not disturbed by my
>signal ­ also 750watts hf. The high performance of Michael, DB6NT’s,
>transverter has a noise figure of 0.4 ­ so no special preamp was needed. The
>blocking behavior of K2 did the other part of the contest. I’m very very
>satisfied by my rig now! I installed the transverter option few days ago and
>the transverter worked great with no additional mods. Absolute outstanding
>performance!
>
>
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Regards  Tony Moore
Phone [phone]
  086 260 7864
Shop at www.satellite.ie
E mail [hidden email].

Satellite.ie
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Tallaght
Dublin 24
VAT No: IE3864265K

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[Gregory P. Daly]

My XV220 has a noise figure around .7 dB, and I haven't measured it's
third order intercept yet..... maybe next weekend. I measured the noise
figure with a HP8593 spectrum analyzer with the noise measurement option
installed. With noise figures this low, the error model for the
measurement is a bit iffy, the error model calculator in the spectrum
analyzer says around +/- 0.2 dB.... so it could be .9, or.5 dB.. It will
be easier to make an accurate measurement with a bit more gain after the
first down converter.... like the rest of the radio.... I remeasured the
noise figure at a different work station using an Agilent "NFA" (modern
noise meter that runs windows and makes nice pictures) and got similar
numbers.... in short, for terrestrial work, I can't tell it from
perfect.... if the antenna has narrow beam width and no big side lobes,
I might be able to tell it from a perfect front end, if it were pointed
at cold space, if it's pointed at the horizon, you'll be able to measure
the temperature of the hills on the horizon..... DX comes at low angles,
KTB will dominate your noise floor until the sun gets very cold..... for
moon bounce, it needs to be better, but not much.

I suspect that for in band adjacent channel interference, the XV series
transverters will be hard to beat... On channel interference is the
operators problem. They stand a bunch of current in the first GaAsFET
it's third order intercept is probably ample. I would be concerned about
out of band performance, there is only one tuned circuit ahead of the
preamp, very loud out of band stations (paging, broadcast, 2-way) may be
loud enough to use up the dynamic range..... unfortunately, any more
filters add loss to the front end, that adds directly to the RX noise
figure, I think Elecraft's choice of front end is the right one. If I go
to a very LOUD! hill top, I have a collection of cavities with tight
coupling loops for 144, 222 and 432, around 1/2 dB loss on each band....
just the trick for out of band troubles.... no help at all for close in
loud signals.

When I get off my lazy butt and measure the TOI I'll report the number
here, I expect it will be a big number. I also expect the XV144 to be
slightly better.... mine is on the bench at the moment, I should be done
in a few days.

The DSP2 is about the coolest thing ever for listening to noise for
hours on end.... not much 220 activity around here most days

The only problem I've run into seems to be in my K60XV's ALC circuit,
and only when the KAT2 is installed..... but that's my next post ;-)

And by the way, I'd like to know how DB6NT reliably measures noise
figure that low..... it's very difficult, I only swear to numbers bigger
than about 1 dB, and only if it's a reasonably high gain device.

73 DE WB7RSG

Greg  


On Sun, 2005-03-06 at 13:18 +0000, Irelands Satellite wrote:

> I wonder how the DB6 unit compares with the XV144 in terms of performance?
>
> Thanks
> Tony Ei7BMB
>
>
> At 09:18 06/03/2005, Norbert Roedel wrote:
>
> >My qth is very exposed on a hilltop in Bavaria ­ in the last years I’ve had
> >big problems with “big guns” next to me. All of them are driving the in
> >Germany legal power of 750 Watts on 144MHz and all of them (4 Stations) are
> >in in maximum distance of 10 miles. In the past I was not able to work weak
> >stations ­ this year I used the K2 as exciter and a high performance
> >transverter TR144H from DB6NT ( www.db6nt.de ) . The result was
> >unbelievable: round about 20kHz away from the stations I was able to work
> >weakest stations and also the other stations where not disturbed by my
> >signal ­ also 750watts hf. The high performance of Michael, DB6NT’s,
> >transverter has a noise figure of 0.4 ­ so no special preamp was needed. The
> >blocking behavior of K2 did the other part of the contest. I’m very very
> >satisfied by my rig now! I installed the transverter option few days ago and
> >the transverter worked great with no additional mods. Absolute outstanding
> >performance!
> >
> >
> >_______________________________________________
> >Elecraft mailing list
> >Post to: [hidden email]
> >You must be a subscriber to post to the list.
> >Subscriber Info (Addr. Change, sub, unsub etc.):
> >  http://mailman.qth.net/mailman/listinfo/elecraft
> >
> >Help: http://mailman.qth.net/subscribers.htm
> >Elecraft web page: http://www.elecraft.com
> >
> >
> >
> >
> >--
> >No virus found in this incoming message.
> >Checked by AVG Anti-Virus.
> >Version: 7.0.308 / Virus Database: 266.6.2 - Release Date: 04/03/2005
>
>
>
>
>
> Regards  Tony Moore
> Phone [phone]
>   086 260 7864
> Shop at www.satellite.ie
> E mail [hidden email].
>
> Satellite.ie
> 3 Deselby Close
> Tallaght
> Dublin 24
> VAT No: IE3864265K
>
> The contents of this email and any attachments are confidential.
> It is intended for the named recipient  only.
> If you have received this email in error please notify the system manager
> or the
> sender immediately and do not disclose the contents to any one or make copies
>
>

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