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#26 2010-04-17 09:36:01

RedHeart
New member
Registered: 2010-04-13
Posts: 7

Re: New dds vfo

I know this is off topic (and I hope people will be patient) - but Adrian, what was the topic of your thesis?

Mine was just accepted (Applied Anthropology- involving research at a homeless program).

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#27 2010-04-19 01:37:30

YO6SSW
New member
Registered: 2008-08-13
Posts: 5

Re: New dds vfo

I have finished computer science and my thesis was based on generating 3d objects out of families of splines.

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#28 2010-05-10 16:33:35

ak2b
Administrator
From: New York City
Registered: 2008-08-12
Posts: 364

Re: New dds vfo

I just finished the DDS vfo. It worked right off the bat. It is not calibratated yet and it looks like it's putting out about +15 dbm - about twice what it should. I need to look a little further and see if I messed something up. I'm using the white LCD. The jumpers are mounted underneath the board if you are wondering. The DDS chip went on without any problems.

http://tomnyc.no-ip.org/images/DizDDS.jpg

Tom, ak2b

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#29 2010-05-10 18:13:06

W8DIZ
Administrator
Registered: 2008-08-12
Posts: 339

Re: New dds vfo

ak2b wrote:

I just finished the DDS vfo. It worked right off the bat. It is not calibratated yet and it looks like it's putting out about +15 dbm - about twice what it should.
Tom, ak2b

Hi Tom,
Here are the latest output specs on the DDS kit:

70-20 milliwatts output into a 50 ohm load from 1,800 KHz to 29,999 KHz, respectively.

73, Diz, W8DIZ

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#30 2010-05-10 18:50:55

ak2b
Administrator
From: New York City
Registered: 2008-08-12
Posts: 364

Re: New dds vfo

w8diz wrote:

70-20 milliwatts output into a 50 ohm load from 1,800 KHz to 29,999 KHz, respectively.

Hi Diz,

I didn't look at the specs before I posted. I had just noted the comment in the instructions that mentioned using a jumper for +7dbm while I was building the DDS. I get 22mW @ 1.8MHz, 32mW @ 10MHz and  19.4mW @ 29 Mhz. Not bad. More is better than too little. I can solve this problem easily enough since there is already space for a pad.
Nice kit. There are a lot of possiblities here. It will be interesting to see the changes as time goes by.

Tom, ak2b

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#31 2010-05-10 20:15:29

wa8qfe
Member
Registered: 2009-02-12
Posts: 18

Re: New dds vfo

My DDS was born about 1 hour ago. Worked fine after fixing 1 bad solder joint on the display header.
not being a programmer, I'll wait for the IF offset function.
Great job DIZ.
Lee

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#32 2010-05-16 14:52:11

wa8qfe
Member
Registered: 2009-02-12
Posts: 18

Re: New dds vfo

I have one minor problem with the encoder..on each full rotation it hits a spot where the detent is between what ever sensing mechanism is internal, causing a jump, ie 5 to 7, or 3 to 5....etc.
I'll change the encoder and that should fix that !
Lee

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#33 2010-05-20 17:30:03

g4edg
New member
Registered: 2009-08-18
Posts: 5

Re: New dds vfo

Hi Diz

Looks like a great piece of kit. Can you tell me the TX-RX turn around time?

I'm using an FCC1/FCC2 combo as a VFO at the moment so the 100MHz max output will be good for mixing on the same side for each band, current set up also has quite a few spurs.

Looking forward the the advanced features!

73 Steve G4EDG

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#34 2010-05-25 06:27:49

W8DIZ
Administrator
Registered: 2008-08-12
Posts: 339

Re: New dds vfo

wa8qfe wrote:

I have one minor problem with the encoder..on each full rotation it hits a spot where the detent is between what ever sensing mechanism is internal, causing a jump, ie 5 to 7, or 3 to 5....etc.  I'll change the encoder and that should fix that !Lee

Hi Lee, Did you ever get the encoder issue fixed?
-Diz

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#35 2010-05-25 06:30:15

W8DIZ
Administrator
Registered: 2008-08-12
Posts: 339

Re: New dds vfo

g4edg wrote:

Can you tell me the TX-RX turn around time?73 Steve G4EDG

Hi Steve,
The QSK time is deteremined by capacitors in the tranceiver circuit.
Of coures, the software could make it real bad but I do not see that happening unless the clock stops smile
-Diz

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#36 2010-06-01 08:22:20

W4DNQ
Member
Registered: 2009-10-06
Posts: 12

Re: New dds vfo

Diz & the group,
Mine continues to work just fine.
I have it connected to Dave's SW-20+ with about 13-14dbm output.
The first harmonic is down 25dbm but lower when I start messing around with the pad resistors.
Still learning here, as Tom knows.!!!
I will try and get some SA pictures to post today.

Also, DIZ, when someone in the group starts working on code for this project, where is it going to be posted ?
I have a programmer that I used on a PIC project that should work just fine. As long as it is in HEX.

73's
Ron

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#37 2010-06-01 09:57:43

W8DIZ
Administrator
Registered: 2008-08-12
Posts: 339

Re: New dds vfo

W4DNQ wrote:

Also, DIZ, when someone in the group starts working on code for this project, where is it going to be posted ?
73's Ron

I can post sample code on my kitsandparts web-site under the DDS project. Just send me the code and a paragraph describing the functions and I'll post it,
with link references here on the forum. I'd love to upgrade this forum to something better with file storage support but I do not have the time.
-73, DIz

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