Guy Giacopuzzi <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Ok, can someone give some details as to the "Italian outfit" that makes
the DDS synthesizer?
Guy,
WA6OQQ
Jim Pruitt wrote:
"Jim Pruitt" <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Hello Eddy.
I have built 2 of the Steve Hageman "Give that Drake Receiver a New Lease on
Life" ( http://www.arrl.org/qst/2004/06/hageman.pdf ) projects from the
June 2004 issue of QST and troubleshooting info at
http://www.geocities.com/hagtronics/r4.html and more troubleshooting info at
N0SS site at http://www.n0ss.net/drake_het_osc_xtal_elim_notes.pdf off of
his page at http://www.n0ss.net/index_general.html . Tom has an Excel
spreadsheet bill of materials at
http://www.n0ss.net/drake_xtal_elim_proj_parts_list.xls but it has not been
updated since 2005. The Hageman FS4 clone works well and looks good. The
cost is a bit high (but what DIY projects are not more expensive than
commercial products these days( (I think mine cost in the neighborhood of
$150 with all new parts and a pc board from Fred at FAR Circuits) and I was
not that impressed with some of the methods used in the design but it is
still a good item and does the job very well. The part that I did not like
was that the segments were 500khz segments (starting at 12.6mhz for 160
meters). Why does that matter since most band segments tuned are 500khz,
you ask. I am in MARS and some of the frequencies fall close to the IF area
where Drake recommends using crystals that start in the middle of the band
segment (when using the T4X series and transceiving). This is mostly a non
issue now, since MARS outlawed older amateur gear on their frequencies.
Other than that the Hageman FS4 clone is ok. It does look nice in the MS4
enclosure with the vinyl overlays that Tom Hammond, N0SS had made that
resemble the face of the FS4. Tom also had ovelays made for a Hammond
enclosure for those that did not want to put it in a MS4.
I also looked very hard at the project at
http://www.jimcom.net/elehobby/r4cdds/index.html which uses an Analog
Devices AD9850 DDS chip. The web page is in Japanese (I do not read or
speak Japanese) but the schematic is viewable and the code for the Pic 16F84
is there.
There are other Analog Devices chips that would probably work better like
the DDS_Controllers group project that uses a AD9912 (I think) DDS chip.
You can also cheat and use a signal generator to replace the FS4 (expensive
waste of test gear) or use a vfo if you have one that covers those ranges
that you need.
The DDS signal generators that use the AD9850 series are probably the
easiest and cheapest to come by as there were many scattered across the web.
I personally do not like having to buy a bunch of crystals since
International Crystal is harder to deal with these days and Jan Crystals web
page is hard to use. I guess Bomar is still in business (correct me if I am
wrong). It is getting harder to buy crystals from crystal manufacturers (at
least at a reasonable price) because the mass production market has moved to
cpu clock crystals.
The Italian outfit that is making a DDS synthesizer for the Drake twins
makes a good product from what I have gathered on this list but that price
is way out of my budget.
If you are inclined to make one of the DDS sythesizers you might look at the
NJQRP DDS daughtercard at http://www.amqrp.org/kits/dds60/ . It uses a
AD9851 which is not included with the kit but may still be available
directly from Analog Devices as a free sample (they are really good about
samples of current production chips but samples are not available for chips
that are at the end of their production life).
Trev (now K6ESE) had a DDS pc board available on the QRP-L group for a while
that used an Atmel AT89S8252 cpu. That project is written up at
http://www.k6ese.com/DDS_Project.htm but is no longer available but the
schematic as well as the source code are available on his site.
There are many many other web sites that have a AD9850-51-54 series DDS
synthesizer project outlined as well as some newer ones like the
DDS_Controller Yahoo group.
Craig Johnson, AA0ZZ, and the group hanging out at the DDS-VFO Yahoo group
and are a great bunch of guys. Craig made the IQ-Pro DDS project for NJQRP
or AMQrp group and now are working on a better version. Craig's homepage is
at http://home.comcast.net/~aa0zz/aa0zz-main.html so you might look at that.
I do not know if the above helps or just muddies the waters but I hope that
it shows you that there are other alternatives to the FS4.
Good luck.
Jim Pruitt
----- Original Message -----
From: EP Swynar
To: [EMAIL PROTECTED]
Sent: Wednesday, December 19, 2007 9:33 AM
Subject: [drakelist] R-4 Series Crystal Alternatives
Good Afternoon All,
I'm curious about the experience of others in the matter of utilizing
possible "...substitutes" for the frequency band oscillator crystals --- be
they synthesizers, self-excited "analog" oscillators, whatever --- in the
R-4 series of receivers, to expand the frequency coverage of same...
To date, my research has come up with three different articles on the
subject, i.e.:
--- August 1972 HAM RADIO magazine ("Frequency Synthesizer for the Drake
R-4";
--- May 1981 QST magazine ("General-Coverage Reception with the Drake R-4C",
and,
--- June 2004 April QST magazine ("Give that Drake Receiver a New Lease on
Life").
Of all these, the May '81 QST appears to be about the simplest to construct,
even though it uses a pair of the now relatively expensive ECG222 (come
NTE-222) dual-gate Mosfet transistors...but how in the world does one attain
(and maintain) solid, stable, & steady crystal-like oscillation in a
relatively simple Colpitts circuit, as high as 40.8-MHz...?!
I'm putting out feelers at this time, because in three short days from now,
I shall be the proud owner of a pair of Drake Twins here...a Christmas
present that I am presenting to myself, just a few days ahead of THE BIG
DAY, Hi Hi.
Thanks in advance, & my vy
~73~ Eddy VE3CUI - VE3XZ
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