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Frequency Limits for Portsdown 2018
Posted: Mon Sep 09, 2019 11:09 am
by F1BFU
Hello
Is the frequency limit of Portsdown 2018 (1200mHz) due to ADF4351? If yes can we replace the ADF4351 for an AD9850 to go up to 2.4GHz? What about the filter modulator?
Many thanks for your responses.
73 QRO Gilles F1BFU /Fr
Re: Frequency Limits for Portsdown 2018
Posted: Mon Sep 09, 2019 11:26 am
by G8GKQ
Hi Gilles
The frequency limit is due to the performance of the IQ modulator. It will work at 2.4 GHz, but the board output is reduced to around -10 dBm. I have seen a picture from it at 3.4 GHz, but the level was very low and the constellation awful.
The ADF4351 functions well to 4.2 GHz (not 4.4 GHz as there is an integer overflow in my calculations at 4.2 GHz).
Dave, G8GKQ
Re: Frequency Limits for Portsdown 2018
Posted: Mon Sep 09, 2019 12:50 pm
by g8gtz
Re: Frequency Limits for Portsdown 2018
Posted: Mon Sep 09, 2019 8:45 pm
by F1BFU
Hello Dave and Noël
Many thanks for your response.
I understand better the decision to move towards SDR Lime. It's an investment but it will allow me to mount in 2.4GHz on QO-100. Do you use Porstdown on QO-100? OMs that are on QO-100 in RB-TV use which hardware?
Thanks again to both of you for your work in DATV. I translated Portsdown Wiki pages and CQ-DATV Newsletters into French. If you wish you can consult them on my Dropbox. I will give you the link to access it.
73 QRO
Gilles F1BFU