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Hi Bob,<br>
<br>
I thoroughly agree with your observations below, except for one. I
don't think it's the best radio in the world. It's Rx has an
impressive IP3, although, bear in mind that the +50 dBm APPEARS to be
referred to the output of the LNA. With 10 dB gain, this reduces to
+40 dBm at the input. This is still 11 dB better than I measured with
Mercury, BUT look at the BDR. This parameter is not easy to
understand from the article.<br>
<br>
My feeling is that it is some way short of the 125 dB that we have
measured for Mercury, and the -133 dBc/Hz for Tx, is way short of the
-150 dBc/Hz for Penny. The problems with this design are twofold.
Firstly, the design uses an oscillator up in the high UHF, so the noise
floor is always going to be worse. But the worst thing is that somehow
the input to one of the amplifiers is at -30 dBm. Now, even with a 1
dB noise figure, this is going to give a noise floor in the - 143
dBc/Hz area.<br>
<br>
IP3 is one thing, but BDR is more important, in my opinion, as it gets
tested with just one guy on the same block, not two.<br>
<br>
73, Greg, ZL3IX<br>
<br>
Robert McGwier wrote:
<blockquote cite="mid:4765FAC9.9090902@gmail.com" type="cite">
<pre wrap="">***** High Performance Software Defined Radio Discussion List *****
I wish to repeat here what I have said to others who have written to me.
I will cede right here and now that the Star-10 is the best HF
transceiver in the world.
So what?
Its relevance to the manufacture of modern radios using modern, commonly
available components, or even to experimenters is negligible.
It is not possible that this radio has 150 dB dynamic range so this is
clearly a misinterpretation or misunderstanding of what the ARRL labs or
Rob Sherwood or others call dynamic range.
In the ARRL lab tests, you take two tones f1 and f2 and measure the
level of the third order products at 2f1 - f2 and 2f2-f1 and using
commonly available formulae compute IMD DR3, IP3, etc. The IMD DR3 is
what the ARRL calls dynamic range. I cannot imagine how you could
construct measurement equipment that would measure third order products
or even detect them in a receiver with "150 dB IMD DR3". It is utterly
preposterous.
My primary gripe with the entire article is the tone and disdain he
shows for fellow amateurs and other people's work. The new editor of
QEX made a truly serious blunder in allowing that pablum into the
magazine. I am sure this is a lesson learned the hard way.
Drentea makes useless comparisons. Drentea is not trying to make a
radio that can be produced for large numbers of people at a price people
will pay. It is indeed a fine piece of engineering craftsmanship and
when it dies, it will be the last of its kind.
So for my part, I cede that Drentea is the finest engineer in the
history of communications and has produced the best transceiver ever
made. That and a buck or two and you get can get a cup of coffee at
Starbucks and the latter is the better of the two.
Bob
N4HY
John Miles wrote:
</pre>
<blockquote type="cite">
<pre wrap="">***** High Performance Software Defined Radio Discussion List *****
Hi, Constantin --
</pre>
<blockquote type="cite">
<pre wrap="">I do now if you remember me or not, I bought your
board for your sysnt published in QEX to test it.
However I wrote to you about another topic
</pre>
</blockquote>
<pre wrap="">Sure! Good to hear from you. I'll cc: your message to the list since that
appears to have been your intent. (You'll need to subscribe if you'd like
subsequent traffic to appear on the reflector without being copied by
someone else.)
</pre>
</blockquote>
<pre wrap=""><!---->
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</pre>
<blockquote type="cite">
<pre wrap="">Very true. I'm sure that many of the points being debated come down to
differences in test methodologies. It certainly does look like a very nice
HB rig, at any rate.
-- john, KE5FX
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</pre>
</blockquote>
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</pre>
</blockquote>
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