R2 phase shift networks


From: David Taylor (david@rmit.edu.au)
Date: Mon Aug 14 1995 - 12:22:28 EDT

Hi All,

My R2 receiver is presently being used on 80m. There's lots of room
for experimenting with phase shift networks for the LO.

I've tried the RC phase shift network (too much attenuation), the
pi section network (much better) and recently KK7B's quadrature
hybrid network from issue 82 of 'Sprat'. This is the best of all, in
fact, I'm impressed.

CRO checks at work showed that the quadrature outputs are close to
equal amplitude when terminated with 50ohms (thinnet terminators
and tees are useful for something!)

At home, connected to the R2, I got the best opposite sideband null
ever and the sweetest, clearest DC sound.

Last weekend was the 24 hour Remembrance Day contest - the premier contest
in VK, where the states compete on all bands for highest
aggregate score. On Saturday night 80m was packed wall to wall with
many big-signal Dxers taking part. Some Ops work the whole 24 hours
non stop, moving to higher bands on Sunday morning! The R2 separated
them easily without a hint of overload. Pity we had visitors who stayed
late :-(

I'm going to build a module with a power splitter and two of these
quadrature hybrid networks so I can get the T2 working as well.

73/72 David

David Taylor Amateur Radio: VK3JKP
Computer Centres CW Ops QRP Club (Aus) No 423
RMIT (Bundoora Campus) G QRP Club No 8937
Melbourne 3083 Australia Internet: david@rmit.edu.au

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