On Sat, 26 Jul 2014, Lostgallifreyan wrote:

Hello. I'm out of my depth here, but I'll try to be coherent in my question..

I had bought a Tecsun PL-390 after seeing several good reviews by radio
amateurs as well as general public. It's awesome, but crash-prone (and if
anyone can guide me to a means of immediately resetting to regain full
control instead of being made to wait 20 munites for power to fade, I'm all
eyes... I like it enough to be willing to risk some effort to modify it,
given some guidance).

I rapidly became aware of the IC inside it when looking for info about its
bad habits, and having already got an AOR AR-3000 recently set up for RS-232
control decided that this might be a way to go with those IC's, because they
can take commands to do many things already, but by means I'm probably not
familiar with.

I Googled "Si4734 OR Si4735 OR Si4735D60 OR Si4770A20 ttl serial" (minus
quotes) and the results are not promising, I already know that there are many
more experimenters out there with better systems than the commercial
offerings than Google has any clue about, so I decided to ask here. The
Elektor project is one way to go but maybe hard to get, a tad large, and
likely improved on by now, too.

Has anyone come up with a SMALL circuit board, some neat rectangular FR4 PCB
easily mounted to some custom-built conditions, containing the IC, ideally
Si4734 or Si4735 (but I don't need RDS, but do want LW and VHF FM stereo as
well as SW. I am looking for ttl serial at 4800 baud, 8N1 standard setup if
possible, so I can turn an old Psion Organiser II XP into the controller, as
those are cheap, easily found, etc.. So in the same spirit, I'm hoping to
find a small board to use this method to make a radio, so I can ecomonically
make more than one, so I have backup and some future-proofing.

The manufacturer was selling boards intended for prototyping, but I'm not
sure if they've done it for all their ICs.

Some of these radios are so cheap, they may be worth buying second one and
using that as a development board. It's an intersting thing, the same IC
being used in multiple radios, the features varying from one to one,
because each has decided what to include. So you get a Grundig G8, and it
has no means of changing selectivity, even if the IC has multiple
bandwidths. The G8 gets good marks for FM reception, but not so much for
shortwave, yet I bet adding a bit of front end selectivity would improve
things. Of course, they can't handle CW or SSB.

The one place I've seen a lot about these ICs is
http://home.comcast.net/~phils_radio_designs/
so poke around there, you may find something of value.

Michael


I'd love it if the Tecsun PL-390 worked reliably, I'm all for an easy life if
I can get one, but apparently it is not to be...

Most interesting to me is that the AR-3000 returns signal strength allowing a
programmer to build something like the ETS tuning method of the Tecsun radios
easily! Scan, measure, store if it looks good... A similar method for these
new DSP radio chips complete with TTL on a tiny board is what I'm looking
for.