Re: Duo with pc headset ssb #eladduo


Neil Smith G4DBN
 

Hi Paul I use a G4DDK Anglian transverter to get the DUO on to 144, but it is quite simple to get around the mathematical and technological issues with the DUO at 144 MHz.  Running 144 MHz on a 122.88 MHz sampled A/D converter means you lose a lot of sensitivity simply because of the way sampling works. The noise figure of the DUO at 144 MHz is extremely poor as a result.  Also there is aliasing, so you get noise from the image frequency as well, and Band 2 FM broadcast breakthrough from around 100 MHz.

Andy G4JNT has designed a filter and amplifier board to improve the DUO performance on 144. Have a look at http://www.g4jnt.com/FDM-DUO_at_VHF.pdf <http://www.g4jnt.com/FDM-DUO_at_VHF.pdf> where all is explained...

Neil G4DBN

On 17/10/2020 23:19, Paul Andrews wrote:
Neil,

Do you use a 144 MHz IF with your 10 GHz system.   I tried using my FDM-DUO configured for 144 MHz with a Khune transverter.  I was not successful looking for the beacon.

73 - Paul - W2HRO

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