xpyttl wrote:
"Ken Scharf" wrote in message
...


Now that I see it might be possible I'm going to try
and make use of those 9954 and 9851 chips I got as
samples. The 9932 looks interresting too, with it's
low power. I also want to get a sample of the 9834,
now THAT's a low power chip, perfect for QRP.


Well, don't be too excited just yet. Even though the chips themselves might
be on a diet, they need a high frequency oscillator to get a decent waveform
out. Those little oscillator cans start to draw amazing amounts of current
when the frequency creeps up. Heck, the ocsillator on my 9850 DDS draws
more current by itself than an entire K1.

FAR circuits has a DDS board that is a little more complete than the NJQRP
dauhtercard, if that's what you are looking for, but the quality of that
board has been pretty bad. I know they are trying to improve it, but I
can't say I've been impressed with the results. On the other hand, they do
have prototyping boards that are quite nice. I picked up a few at a hamfest
this past fall that are pretty decent for the TSSOP DDS parts. And they are
a LOT cheaper than the individual adapters. However, their online catalog
doesn't have the selection they had at the hamfest, so maybe a call to them
would be in order.

The NJQRP daughtercard really does reduce the pain of all this, but both the
daughtercard and the FAR circuits DDS card are for the 9850, which is
getting a little stale. Sounds like you want to play with some newer stuff.

Also take a peek at some of the TI stuff. They have synthesizers and
"transmitter" chips that are very reasonably priced. Although they are
intended for very high frequencies, Steve Weber has made them work down into
more reasonable frequencies, and prescalers are only a couple of bucks.

I haven't found a link where you can buy the NJQRP daughtercard, he
seems to have the artwork for downloading but that won't do me much
good. The 9851 seems to be pin compatible with the 9850 and will go
higher in frequency using a lower frequency (lower powered) oscillator.
The 9954 family is much smaller in size than the 9850 family (closer
pin spacing) so dead bug on these would be about impossible, the
circuit board is a must. I found some other bread board adaptors but
the problem is that there can't be any traces UNDER the 9954 because
there is a ground pad there. I can carefully cut away the unused
portions of one of these (http://www.devrs.com/store/) which is a
universal breadboard, drill a hole through the middle and solder
a wire to the ground pad. BTW I thought I'd have a problem interfacing
to the 9954 because it runs on 1.8v (how to hook it to a 5v 8051?), but
the io part of the chip is powered by it's own pin that can run at 3.3v
and then it will tolerate 5.5v max on the digital inputs. Problem
solved!

BTW many here seem to like PICs, but I'm just more familiar with the
8051 series. IF you don't need external ram or io on the 8031 and
and use an external EPROM you still have 16 io lines available, it's
then a three chip solution (8031, 74x573, 27x512). There are simulators
C compilers and assemblers for the 8051 that run on Linux (don't know
about the pics). I DO wish that people that post articles using these
micros on the web or in qst would make the SOURCE CODE available!!!
Not doing so is like NOT making the SCHEMATIC available for a homebrew
article!!!