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[linrad] Re: Linrad via Ethernet

Autotrax allows multilayer boards and I dont see any major problems - one issue is the lack of a good "copper pour" tool - still you can get around this with multiple fills - just a bit slow and tedious. The boards dont look as though they would be particularly complex. Ground and power planes would have to carefully designed to separate the analog and digital sections though and minimize noise A significant issue is the cost of getting a prototype or small run - it will be at least AUS$400-500 in tooling before any boards are made - expensive if I make a mistake :)
I have set up a Wiki using TikiWiki and E Smith/Linux - if people were interested in such a project this would allow collaborative work as schematics and board drafts could be posted here and commented on/worked on etc. Still trying to see it from the net however (I can see it on my home network) - obviously I havent configured something right 
I would be grateful if someone could point their browser to

http://www.wargr.com/linrad/tiki-index.php

and tell me if it works

Thanks
Richard

leif@xxxxxxxxxx wrote:


Hi Richard,
LO (Xtal osc) (What freq?) ->74AC14 X6 -> AD6644 -> AD6620 -> AD6620 -> ethernet -> PC 
The frequency would be the highest possible. The data sheet says maximum
guaranteed sampling speed 65 MHz. The SDR-14 uses 66.66667. I think 65.000 MHz would be fine. It becomes easy to lock it to a 10 MHz reference one way or the other:-) 


If we were to do one AD6620, then a second one wouldnt be too hard.

Absolutely:-)


Could one do all this on a double sided board?

Maybe. The AD6644 data sheet suggests a design with 4 layers.
The clock is supplied via a transformer and two schottky diodes
limit the amplitude. Probably one could feed the transformer
with a sinewave directly from the LO.
Alternatively a multilayer board would be possible, though I have never done one 
Maybe it would be a good idea to make a small 4-layer board with
the X-tal oscillator, the AD6644 and appropriate buffers just as suggested in the AD6644 data sheet. This should be a very low risk project. 
As far as I understand one can buy this board for USD 200 from Analog Devices
http://www.analog.com/en/prod/0%2C2877%2CAD6644%2C00.html#price
Then one could connect it to a two-layer board with two AD6620 and an
ethernet interface.


I still use the old Autotrax (1991 - precursor of Protel)
As of a couple of years ago, a local board house still accepted this


73  Leif / SM5BSZ



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