[hpsdr] Follow-up on Hermes-Lite

[rodwall1234 at gmail.com]

Hi Steve,


Opppssss… yes of course there is only one Rx connector. I do have a great N2PK VNA so I already have a VNA for my needs. What I was thinking of is a Club project that is both a SDR and VNA. It would allow you to use it as a VNA to adjust your antennas then to use it as a SDR. Thanks for the link for the pysdrvna VNA. I’ll have a look at that tonight when I have more time.


Thanks for your help,


Roderick Wall,vk3yc.





From: Steve Haynal
Sent: ‎Thursday‎, ‎17‎ ‎April‎, ‎2014 ‎12‎:‎14‎ ‎AM
To: Rod Wall, hpsdr at openhpsdr.org





Hello Roderick,



Please remember that the 2 RX in the Hermes-Lite and  5 RX in the Hermes use the same input and ADC. So 1 detector lets you listen to multiple bands on the same antenna. If you are interested in an inexpensive VNA, checkout another project of mine: https://code.google.com/p/pysdrvna/




73,




Steve

KF7O







On Wed, Apr 16, 2014 at 2:52 AM, <rodwall1234 at gmail.com> wrote:




Hi Steve,




Thanks for your reply. As I’ve indicated,  a VNA for $150.00 would be great. And if it can have two Rx detectors it would be even better to do Reflection and Transmission measurements with out having to change the connections to the DUT.




Good luck with the development, I’ll like to build one and help test it when ready.




Regards,




Roderick Wall, vk3yc.





From: Steve Haynal
Sent: ‎Wednesday‎, ‎16‎ ‎April‎, ‎2014 ‎1‎:‎48‎ ‎PM
To: hpsdr at openhpsdr.org





Yes, the Hermes-Lite should be usable as a VNA, although I have not tested this. Currently, it runs in half-duplex mode. I tried full-duplex but had some issues with noise at various front-end gain levels. I have asked ADI for help with this. You will have to use full-duplex for the VNA and the levels of noise I saw probably won't matter much for a VNA. Ideally, I'd like to see half-duplex for regular operation to keep the power consumption low, and then switch to full-duplex when needed for a VNA.



The design is now only 1 RX and 1 TX to keep the compile time down. The limitation yo will run into when compiling with 2 RX and 1 TX is not enough RAM resources. The Hermes had some large buffers because I believe it could. These will have to be reduced to fit 2 RX and 1 TX.




73, 




Steve

KF7O
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