Rod:
Si570's are available in different I2C addresses if you order them
from the silabs webpage. I just got 2 with an address of 86 rather than
85 to do just what you did.
Dave - WB6DHW
<http://wb6dhw.com>
On 5/31/2015 9:01 PM, Rod wrote:
Hi all,
I am testing the new Minima3 front end with the old Minima2 20 MHz IF and audio.
The results so far are impressive.
Measured with a FLUKE 6062 signal generator, I am getting -128 dBm MDS on 14 MHz.
Measured with an HP 8553 specan, I see -38 dBm LO signal at the antenna terminals.
I was very impressed with the LO suppression. (N.B. currently I do NOT have an LP
filter on the antenna input- it is connected directly to the mixer).
I should add a note here: the BFO is not a stock Minima2 BFO. I put a second SI570 into
use as a BFO, so I would have digitally controlled BFO. I used a guesstimated pad on the
SI570 signal path to the product detector.
Because SI570s are only available with one I2C address, and therefore one cannot
put two SI570s on the same I2C line, I put an Adruino Mini-Pro in the BFO box,
and I use a serial line to it to select BFO frequencies.
Also, my construction technique is ugly-style, but with separate shielded compartments
to enclose the 1. mixer/postmix amp, 2. crystal filter, 3. IF amp, 4. bfo/product dector,
5. audio preamp. The audio power amp is not in an enclosure. The shielded enclosures
are a mix of Altiods tins, and PCB-soldered boxes.
I am using homebrew ATmega software, and it has a Kenwood TS440 emulation CAT interface.
Works nicely with FLDIGI.
Farhan, thank you for the design ideas-- I really enjoy the audio quality, and with the new
Minima3 front-end, the receiver really came to life.
Rod KM6SN
