[hpsdr] OCXO's for Griffin

[Henry Vredegoor]

  Hi Kevin, All,

Sorry for having quite a different opinion on OXCO's and the like for 
Griffin, but I  would leave out all the OXCO and GPS hardware.
Just implement the external OXCO header and the external 10 MHz 
reference clock input.

My reasoning for this is that if a particular user wants to have a high 
precision clock in a stand alone setup he can easily add an external 
(small, could be simple or more complex design)  PCB with an OXCO or add 
an external 10 MHz or GPS reference clock (maybe already present in the 
shack eg. from Excalibur or a Thunderbolt and the like, (maybe even 
Gibraltar in the future?))
I think one of the reasons of having a standard reference clock in the 
shack is that all equipment  uses this one single clock reference 
instead of keeping up with a number of different single "references".
(I would for this reason prefer a board without any OXCO)

I see there is a big advantage of having everything in one standalone 
package of course, but I see advantages of leaving these out: besides a 
much simpler design, a lot lower initial cost for a buyer.

You maybe also want to avoid the testing/manufacturing difficulties for 
TAPR (if these are going to be "mass produced" by TAPR) having multiple 
OXCO types and hence also different populated board types.
 From the past experience with eg. Excalibur this ends up in TAPR only 
making one version, with a particular fixed type of OXCO (for all good 
reasons for them)  but with unnecessary higher costs for a user who 
doesn't want this type of OXCO or no OXCO at all (and so save the money 
for a rather expensive high quality OXCO part)

Besides that I believe that from the experiences with Mercury and 
Penelope, the used !25 MHz (10 MHz) clock XO hardware on these boards 
are not that bad at all wrt. frequency stability.
Maybe even so good that without an external high precision and stable 
clock reference WSPR should be possible?
How does the WSPR (by K1JT) software when used with a standard, analog, 
(non-HPSDR) transmitter handle (compensate) this aspect?


Just my 2 Eurocents ......

This is meant as positive comment, no offense intended.
Thank you for taking up this new wonderful project for the cool world of 
HPSDR.

In fact so cool that I re-registed my old call "PA0HJA"; effective as of 
last Saturday 28-AUG-2010 !!!

73's,

PA0HJA  Henry, The Netherlands.   ( Changed nickname on Teamspeak ....   
;-)   )


On 8/29/2010 11:14 AM, Kevin Wheatley wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> I've started the schematics for Griffin based on the block diagram posted on the Wiki, the aim is to provide a number of OCXO footprints on the PCB, currently I have three:
>
> http://www.vectron.com/products/ocxo/co714718s.htm (available via surplus from time to time)
> http://www.doveonline.com/item.php?ITEM=DOV013501&DESC=TCO-6730&DESC2=10.000MHZ+12V+2TTL+OCXO (available via surplus from time to time)
> and the VFOV300 from Valpey Fisher http://www.valpeyfisher.com/Products.aspx?ProductCode=OCXO
>
> are there any others I should consider?
>
> 73's
> Kevin
>
>
>
>
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