Showing posts with label m0ppp. Show all posts
Showing posts with label m0ppp. Show all posts

15 Nov 2011

137kHz Transverter RX Desense

When testing my transverter on the bench today I noticed the receiver was being desensitised by the undriven TX strip. I don't switch the TX part off when on RX, I just don't apply 10MHz drive into it. There must be some source of low level noise from these stages when on RX as the desense is around 10-20dB. Despite this I am still able to copy M0PPP at 182km pretty consistently these days on 137.5kHz WSPR. I need to fix this problem before this project is boxed and "finished". When the TX strip is powered down the sensitivity is very good indeed.

10 Nov 2011

137kHz WSPR - big SUCCESS at last!

After yesterday's disappointments today has been a whole lot better on 137.5kHz with my best WSPR DX report ever and a report from my second DXCC country on the band.  First several reports from GW0EZY in mid-Wales (251km) and then one from M0PPP in the north of England (off the side of my TX loop too - 182km) who I heard last night for the first time.  I've copied him several times tonight as well as PA3EGO. The transverter now puts out about 20W, but the ERP is still only around 200uW based on the loop current and enclosed area. I'm tempted to put it in a box at last as I now know this system is capable of decent range on a good night like tonight.