Friday, March 4, 2016

Update on modifying a G4DDK Anglian transverter to work at 124- 126MHz for 2300MHz driver use

You remember my cunning plan to drive a DB6NT 144 - 2320MHz transverter at 124 - 126 MHz to produce signals in the new UK NoV band of 2300 - 2302 MHz? Well I've already proved that the DB6NT transverter will work, (see earlier post here) so today I modified the 144 Anglian board and built and tested the kit.
Had an extremely productive couple of days using the excellent (and free)  QUCs circuit analysis software to model the filters and diplexers in G4DDK's Anglian 28 - 144MHz transverter.
I've now tweaked the designs to move them to centre on 126MHz to best cover the proposed EME section above 2301.900.
Results are just perfect and with just a few minor component changes it now performs centred on 126MHz producing up to +22dBm, output and without any changes to the RX front end noise matching, around 20 dB of gain at 2.4dB noise figure. More than adequate as an IF system. I'm sure with more work it could be made to produce the 1.6dB noise figure of a standard 144MHz Anglian but "do the maths" and you'll see that with a low noise transverter in front of it, it's just not necessary.
Now to connect it to my 13cm EME system and check that any low level stray radiation in the 124MHz airband is acceptable. Some wandering around the garden with a widebanded FT817 is called  for!
Once it's fully operational I plan to write the whole project up in detail in Scatterpoint.   

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