Steve,
I believe the 500 and 800hz mechanical filters available for the 75A4 have
much steeper skirts than the 100 and 1000hz filters of the R-390A. The 75A4
also featured passband tuning and a notch filter, neither of which were
offered on the R390A.
GL/73,
Barry N1EU
>From: Steve Ireland <sire@iinet.net.au>
>To: topband@contesting.com
>Subject: Topband: Collins R390 and 75A4 on 160m
To: <topband@contesting.com>
>Date: Sat, 03 Aug 2002 12:07:52 +0800
>
>G'day all,
>
>I have a 1955-vintage Collins R390 here and am curious about whether anyone
>on the reflector has done any comparisons on 160m with the 75A4 - or what
>anyone who has a R390 thinks of its performance on 160m.
>
>My R390 is in original unmodified condition and I am not a vintage
>collector (i.e. am not concerned about modifying it), so am also wondering
>if there is anything I can do do improve its 160m performance.
>
>My other idea is that I might be better leaving the R390 'as is' and trying
>to find an AM SWL-type of person who is more interested in this type of
>radio, trading/selling it, and then looking for a 75A4 instead. Looking at
>the R390 circuitry it seems an pretty amazing receiver - probably more
>sophisticated/complex than the 75A4 in its design.
>
>What lays behind this is am putting together a 1950s type amateur station
>for 160m. For the tx I have a Panda Cub transmitter from the UK, with an
>807 PA. This is a commercial unit, made entirely from world war 2 surplus
>parts. This weekend, I'm building a pine console/radio shelf to house the
>equipment - great fun!
>
>Vy 73,
>
>Steve, VK6VZ
>
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