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Henry Vredegoor wrote:
<blockquote cite="mid:73A6DDF3E6EB440ABC2554F4242E1927@Blues"
type="cite">
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<div><font color="#0000ff" face="Arial" size="2"><span
class="377032322-06042009">Hi Alberto, All,</span></font></div>
<div><font color="#0000ff" face="Arial" size="2"><span
class="377032322-06042009"></span></font> </div>
<div><font color="#0000ff" face="Arial" size="2"><span
class="377032322-06042009">I think you mean the HP-10811 XO instead of
the HP-80111?</span></font></div>
<div><font color="#0000ff" face="Arial" size="2"><span
class="377032322-06042009"></span></font> </div>
<div><font color="#0000ff" face="Arial" size="2"><span
class="377032322-06042009">I saw the HP-10811 on Ebay for about US$
200 (after I heard about it in the conversations of Graham on the
recent Teamspeak)</span></font></div>
<div><font color="#0000ff" face="Arial" size="2"><span
class="377032322-06042009">I have to read some more I 'm afraid after
all the good info in all the posts here. (Thank you all!)</span></font></div>
<div><font color="#0000ff" face="Arial" size="2"><span
class="377032322-06042009"><span lang="N"></span></span></font> </div>
<div><font><span class="377032322-06042009"><span lang="N"><font
color="#0000ff" face="Arial" size="2">I don't know what one would have
to pay for the Trimble Resolution-T or the </font><span lang="N"><font
face="Arial"><font color="#0000ff"><font size="2">iLotus M12M<span
class="377032322-06042009"> pointed to by Graham </span></font></font></font></span><font
color="#0000ff" face="Arial" size="2">but if I aim for an "HPSDR
average-per-card" budget of say US$ 150 to US$ 2<span
class="377032322-06042009">5</span>0 and b<font size="-0"><span
class="377032322-06042009"><span lang="N"><font color="#0000ff"
face="Arial" size="2">oth being not surplus market items and priced as
such </font></span></span></font>I think the budget will be too
small........! :-( </font></span></span></font></div>
</blockquote>
<br>
<small><font face="Verdana">Hi Henry,<br>
<br>
sure, what I meant was the HP-10811, but I had a temporary failure
in some neuronal interconnections... :-)<br>
Mine was salvaged from an otherwise defunct Z3801A, and it is of the
double-oven variety, which supposedly<br>
should be less influenced by the ambient temperature variations.<br>
<br>
The Resolution T was promised to me as a sample unit, at a cost ranging
from 30 to 60 Euro, he wasn't sure yet.<br>
Add to that the relatively low cost of an Atmel AVR microprocessor and
some other components, and the cost<br>
should remain within the bounds you specified. The advantage of the AVR
uP is that with its PWM you can <br>
do without a sometimes hard to find 18-bit DAC to generate the EFC. The
limit of 10 bits for the PWM can be <br>
easily taken care of by using the DDA (Digital Dithering Algorithm),
which adds another 10 bits to the resolution<br>
of the EFC voltage. You need a very good low pass filter (corner
frequency 0.25 Hz, -130dB [computed, not measured]<br>
at 3.9 Hz), but it is not difficult to design and implement.<br>
I did a similar project in 2004 and it is still working well on my
bench.<br>
<br>
73 Alberto I2PHD<br>
<br>
</font></small>
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