[Premium-Rx] R1451A

[Michael O'Beirne]

Dear Bill

I have looked at the only reference on the net to this set.  A distinct 
physical resemblance to the Telefunken e893 submarine radio.

What was of concern was the 40dB aerial attenuator switch.  Such high 
attenuation inevitably suggests that the signal handling range was limited - 
as one expects with early transistorised receivers.

Do you know which parts of the USN used it?  The compact size suggests 
perhaps for submarines or small warships, given that the large warships were 
happy to accommodate a battery of big heavy R390As.

73s
Michael
G8MOB

----- Original Message ----- 
From: "Bill Tweedie" <bill.tweedie at bigpond.com>
To: <Premium-Rx at mailman.qth.net>
Sent: Tuesday, January 01, 2013 3:18 AM
Subject: [Premium-Rx] R1451A


> Hi All
> For those who are interested-
> This set appears to differ somewhat from the VLF version.
> Single conversion fron 0.5 MHz to 8 MHz with 455 KHz IF with filters from 
> 0.1KHZ TO 16 KHZ.
> Double conversion from 8 MHz to 32 MHz. First IF is 3.455MHz ( incl a 
> 'roofing filter' at 3.455MHz)
> then 455 KHz through 455KHz filters to selectable AM and product 
> detectors.
> Has an ISB facility with two mechanical filters, one for each sideband in 
> addition to the above filters.
> Has a fixed 455KHz BFO plus a variable facility from -8 KHz to +8 KHz.
> FET front end with two RF stages & attenuator.  Extensive shielding 
> section by section.
> It is likely that oscillator radiation was minimal fro obvious reasons.
> AGC & manual controls. Construction is a work of art.  Circuit boards are
> Would have cost a fortune to produce in the 1960s.
> Bill