[Premium-Rx] Plessey 2280 series

[Michael O'Beirne]

Good evening gents,

A propos John Green's comments, I believe that a special version of the 2282 
was made for the RAF (and possibly the China News Agency) with a digital 
display for the BFO.  I have no written evidence and this is from long term 
memory, but I will contact an ex-Plessey friend who sold me my 2282 and will 
report back.

I know that Plessey made a sales pitch at GCHQ because I hold some of the 
draft documentation, but I don't know if GCHQ bought any.  It is interesting 
because it reveals that GCHQ insisted on a 100kHz IF output even though the 
second IF is 1.4kHz, and furthermore that the sideband sense at the antenna 
input had to be reproduced at the 100kHz output.  One can but guess what 
manner of computerised filtering was hung onto the IF output - perhaps a 
form of very early DSP as well as the usual spectrum display add-ons.

Unfortunately the 2280 series does not seem to have sold well and then of 
course Plessey vaporised after the take over by Siemens and GEC, and 
technical support for these extremely fine radios disappeared.  The major 
problem as far as I am concerned is the "wobbly" synthesiser tuning, the 
result of a very long lock up time on the PLL of about 60 mS (presumably to 
improve the the LO phase noise response), though it's usually ok when you 
tune with the keyboard.

73s
Michael
G8MOB