Frequency Limits for Portsdown 2018

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F1BFU
Posts: 19
Joined: Sun Aug 04, 2019 1:53 pm

Frequency Limits for Portsdown 2018

Post by F1BFU » Mon Sep 09, 2019 11:09 am

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

G8GKQ
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Re: Frequency Limits for Portsdown 2018

Post by G8GKQ » Mon Sep 09, 2019 11:26 am

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

g8gtz
Posts: 1155
Joined: Wed Apr 07, 2010 6:26 pm

Re: Frequency Limits for Portsdown 2018

Post by g8gtz » Mon Sep 09, 2019 12:50 pm

See https://wiki.batc.org.uk/Portsdown_Output_Levels for more detail.

73

Noel - G8GTZ

F1BFU
Posts: 19
Joined: Sun Aug 04, 2019 1:53 pm

Re: Frequency Limits for Portsdown 2018

Post by F1BFU » Mon Sep 09, 2019 8:45 pm

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

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