Helical filter for 2m

[Alex VE3NEA]

For more than a year I was unable to receive signals from the satellites on the 2m band because of the strong interference from a nearby tower. I solved the problem by building a narrowband helical filter that suppressed the interference and prevented overloading of my SDR. The details are here:

https://ve3nea.github.io/helical.html

Now I can use both V/U and U/V satellites. I have already made a few CW and FT4 QSO using AO-73, JO-97 and AO-7.

73 Alex VE3NEA

[Jack Blake]

How you get a FT4 QSO on AO73? I’ve tried but the uplink drifts so much on the satellite hard to get a lock. I’m using 9700 and CSN Sat box. DE AI4LL

Jack L. Blake

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[Alex VE3NEA]

On AO73 I could not find any FT4 stations to work, but I decoded my own transmissions in every pass using SkyRoof + SkyCAT + IC-9700. The CAT Delay setting In SkyRoof was 100 ms.

[Paul Andrews]

You guys are having too much fun with satellites.  I need to get involved again.

73 - Paul - W2HRO 

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[Alex VE3NEA]

The downlink frequency of AO-73 is pretty stable, within 100 Hz between the passes. A manual correction of about -200 to -300 Hz can be set once, and no further adjustments will be necessary. The uplink frequency error, however, changes significantly from pass to pass, but with the wide waterfall of SkyRoof it is easy to set the right offset at the beginning of the pass. As I mentioned, I am decoding my own transmissions on AO-73 but cannot see any other FT4 stations.