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2 dB better reception in JT65 mode

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PA2V

2 dB better reception in JT65 mode

Hi guys.

I have compared my brand new K3 against my IC756pro2 in JT65b mode while
doing EME on 432 MHz.

With the same transverter, antenna, preamp etc. I see stations 2 dB better
with the K3.

It also made me see another station at -30 dB that I could not detect on the
756.

I just wonder, is this because the famous low noise architecture or just the
clean audio of the K3?

The K3 is connected via the line-out to a Delta44 soundcard at the PC.

Audio levels have been carefully checked to be sure I am doing exactly the
same to both rigs.

The RF path 28 MHz > 432 MHz > was exactly the same all the time. I switched
with relays between the rigs.

Is there any other K3 owner who did the same test on here?

73, Peter PA2V

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Don Wilhelm-4

Re: 2 dB better reception in JT65 mode

Peter,

I would attribute it to the superior dynamic range of the K3.
I have not done similar tests.

73,
Don W3FPR

On 1/24/2014 5:01 PM, PA2V wrote:

> Hi guys.
>
>
>
> I have compared my brand new K3 against my IC756pro2 in JT65b mode while
> doing EME on 432 MHz.
>
> With the same transverter, antenna, preamp etc. I see stations 2 dB better
> with the K3.
>
> It also made me see another station at -30 dB that I could not detect on the
> 756.
>
> I just wonder, is this because the famous low noise architecture or just the
> clean audio of the K3?
>
> The K3 is connected via the line-out to a Delta44 soundcard at the PC.
>
> Audio levels have been carefully checked to be sure I am doing exactly the
> same to both rigs.
>
> The RF path 28 MHz > 432 MHz > was exactly the same all the time. I switched
> with relays between the rigs.
>
> Is there any other K3 owner who did the same test on here?
>
> 73, Peter PA2V
>

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Edward R Cole

Re: 2 dB better reception in JT65 mode

In reply to this post by PA2V

Peter,

EME is all about detecting the weakest signal (e.g. MDS) so I would
attribute this to the low-phase noise of the K3 LO. In fact one of
the determining factors for my to chose it as my eme IF
radio. Dynamic range would be more important in HF where very strong
signals are present at adjacent frequencies; something all eme'rs
would love to hear!

The other attributes that make the K3 ideal as eme IF are:
1) Excellent transverter interface, KVX3
2) Excellent frequency stability with the EXREF option
3) Design for CW
4) Design for soundcard interface for data modes.

I just restored my 16-foot dish for 1296 reception so will be looking
for weak signals from the Moon with my K3/10 + 1296/28 transverter.

enjoy the extra dB!

73, Ed - KL7UW

-----------------
Subject: [Elecraft] 2 dB better reception in JT65 mode
Message-ID: <000d01cf194f$ceafc410$6c0f4c30$@pa2v.com>
Content-Type: text/plain; charset="us-ascii"

I have compared my brand new K3 against my IC756pro2 in JT65b mode while
doing EME on 432 MHz.

With the same transverter, antenna, preamp etc. I see stations 2 dB better
with the K3.

It also made me see another station at -30 dB that I could not detect on the
756.

I just wonder, is this because the famous low noise architecture or just the
clean audio of the K3?

The K3 is connected via the line-out to a Delta44 soundcard at the PC.

Audio levels have been carefully checked to be sure I am doing exactly the
same to both rigs.

The RF path 28 MHz > 432 MHz > was exactly the same all the time. I switched
with relays between the rigs.

Is there any other K3 owner who did the same test on here?

73, Peter PA2V

73, Ed - KL7UW
http://www.kl7uw.com
"Kits made by KL7UW"
Dubus Mag business:
[hidden email]

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Jim Brown-10

Re: 2 dB better reception in JT65 mode

On 1/25/2014 9:50 AM, Edward R Cole wrote:
> The K3 is connected via the line-out to a Delta44 soundcard at the PC.

I don't know anything about this sound card, but I've worked a lot of
JT65 and RTTY, and I found that a good semi-pro audio USB interface
improved JT65 decoding a LOT as compared to the sound card built into my
Thinkpad. With extensive testing of two computers next to each other
connected to the same audio, the USB interface gave me twice as many
decodes in a pass using JT65-HF, and gave me decodes about 10dB lower
into the noise (fairly often in the range of -20 to -22).

I bought and tested three USB interfaces -- a Numark (about $35) a
Tascam (about $75), and a little mickey-mouse sort of thing. The Numark
and Tascam were equally good at decoding both JT65 and RTTY. The little
thingy worked, but was so poorly built I wouldn't recommend it. The
Numark has no model number, the Tascam has been discontinued and
replaced by one with more inputs and a higher price. I'm confident that
it works as well. Both the Numark and the Tascam units have line inputs
and outputs, and RIAA inputs. The Tascam has inputs for guitar and pro
mics, so it's a bit more versatile in accepting different input levels.

The Tascam is hooked up to my "main" K3, the Numark gets used with the
other radio when I do SO2R RTTY contesting.

73, Jim K9YC

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EricJ-2

Re: 2 dB better reception in JT65 mode

There is a lot of "Just use any old soundcard, even a dongle" type of
advice about digital modes. I went from nearly 100% CW to nearly 100%
JT65 and JT9 on HF so I've tried a few things. I could decode down to
about -18 or so with the built in sound card. I got an EMU 0204 for use
with an LP-PAN and decided to try it for JT65/9. I could decode down to
-23 and occasionally lower. I tried a SignaLink USB and can usually
decode down to -21 and sometimes -22.

ANY sound card will work for sound card modes, just like ANY piece of
wirewill work for an antenna. But there is a difference in sound cards
for digital modes and there is a reason I use a TH7 at 60' instead of a
mag loop antenna despite the fact that they both "work".

Eric
KE6US

On 1/25/2014 1:38 PM, Jim Brown wrote:

> On 1/25/2014 9:50 AM, Edward R Cole wrote:
>> The K3 is connected via the line-out to a Delta44 soundcard at the PC.
>
> I don't know anything about this sound card, but I've worked a lot of
> JT65 and RTTY, and I found that a good semi-pro audio USB interface
> improved JT65 decoding a LOT as compared to the sound card built into
> my Thinkpad. With extensive testing of two computers next to each
> other connected to the same audio, the USB interface gave me twice as
> many decodes in a pass using JT65-HF, and gave me decodes about 10dB
> lower into the noise (fairly often in the range of -20 to -22).
>
> I bought and tested three USB interfaces -- a Numark (about $35) a
> Tascam (about $75), and a little mickey-mouse sort of thing. The
> Numark and Tascam were equally good at decoding both JT65 and RTTY.
> The little thingy worked, but was so poorly built I wouldn't recommend
> it. The Numark has no model number, the Tascam has been discontinued
> and replaced by one with more inputs and a higher price. I'm confident
> that it works as well. Both the Numark and the Tascam units have line
> inputs and outputs, and RIAA inputs. The Tascam has inputs for guitar
> and pro mics, so it's a bit more versatile in accepting different
> input levels.
>
> The Tascam is hooked up to my "main" K3, the Numark gets used with the
> other radio when I do SO2R RTTY contesting.
>
> 73, Jim K9YC
>
>
> ______________________________________________________________
> Elecraft mailing list
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> Post: mailto:[hidden email]
>
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> Please help support this email list: http://www.qsl.net/donate.html
>
>