[Premium-Rx] Racal RA1772

[Pat1McA at aol.com]

Hello Alberto,
 
After repairing over 20 RA1772s and over 45 RA1792s I think that I can  
comment on this subject.
 
The RA1772 appears to have been designed, at the time, with little  regard 
for cost saving.
There is a reason for this. After the valve/tubed RA17 receiver, Racal  was 
struggling to produce a comparable solid state successor, in the event they 
 produced the transistorised RA1217 - which turned out to be  a disaster in 
terms of performance.
I remember visiting Portishead Radio, in those days GRL (1612kHz), but  
later as GKA/B etc, around 1969, when they had replaced the RA17s with RA1217s  
and the Operators were NOT happy at all !
The general performance was so dreadful that Racal just had to come up with 
 a satisfactory replacement.
Enter the RA1772 which was designed from the floor up with no short cuts.  
The result was a truly superb receiver.
Consider at the same time competition was fierce from Marconi, Redifon,  
Plessey, Rohde & Schwarz, Telefunken etc etc,  remember this was in the  era 
of "Real" HF CW and voice SSB Communications. WJ did not get a look in, not  
at least on this side of the "Pond!"
 
The thing that sets the RA177X series apart from the others is the very low 
 noise synthesiser with discreet crystal filters, this is basically  superb 
and the excellent rotary Tuning shaft encoder  is copied right up to the 
later RA3701 model. Unfortunately the  RA1772 "hang" type agc lets it down - 
for Amateur use.
 
The RA177X series had a useable Preamplifier that would show signals down  
to -139dBm with a 3Ip of around +35dBm. This was seriously good in 1974, it  
still is now! Most other receivers of the time, the EK070, E1700, and later 
 E1800 did not have a preamp and consequently had impressive 3Ip figures. 
But,  under most common circumstances this does not matter at all for us  
Amateurs.
 
The RA1772 was unbelieveably and expensively labour intensive, rather  like 
the E1500/1700. Even worse for wiring intensity was the RA1784 and  
RA1778/9 series. So the RA1792 was born, a beancounters dream!
 
I think that there is no comparison between a properly aligned (few were)  
RA1772 and an RA1792. The RA1772 wins hands down BUT from the operational 
point  of view the RA1792 is absolutely unbeatable!!!
The later RA1778/9 series is nicer to use than the RA1772 but much  harder 
to find now.
 
For my choice the finest Racal HF Receiver is the Remote Controlled RA1784. 
 These were hugely expensive but had the option of a switchable  600Hz  
Roofing Filter in them, rather like the RA1772 prototype I was offered many  
years ago,and, like an idiot, did not purchase! That had a switch, in place of 
 the normal AFC one that switched in an Optional CW Roofing Filter - an 
Option  that got dropped by Racal as being too expensive at the time, around 
£600 in  19772.
 
If you compare an RA1772 against an RA1792 on the bench the RA1772 wins  
easily on readability but then, as usual, everything is " Horses for Courses"  
with the 1792 being much more intuitive to use, but (I believe) it was an  
American design based on the RA6790GM. For intuitiveness and ease of  
operation nothing beats American Radios eg. WJ8711A ,  WJ8718, etc etc
 
Regards & 73 
 
Pat G3YFK