[Premium-Rx] RA1772 and 1778 manufacturing dates

[Danny Higgins]

Michael/John,

The RA1772 was in production when I joined Racal in 1975.  The one that 
was in the ham shack had serial No 007 and had spent a long time in the 
tropics.  We had to re-wire all of the PSU cabling that had gone brittle 
in the heat and humidity before we could use it.

The RA1778 was not developed until about 1978/79.  I thought I could 
narrow it down a bit as I have a set of the original RCA CD4036 memory 
chips that were used.  Unfortunately the date code appears as "5 26", so 
no help there.

The marine version of the RA1772 is the RA1776.  This had the mains 
switch installed "upside down", a different level of suppressed carrier 
for AFC, and a different antenna input impedance below 1MHz.  I had one 
on my bench at work when a salesman was showing a customer around.  When 
asked what the difference was between the 1772 and the 1776, the 
salesman said "That one covers the marine bands"!

Danny, G3XVR

Michael O'Beirne wrote:
>
> ----- Original Message ----- From: "Michael O'Beirne" 
> <michaelob666 at ntlworld.com>
> To: "John Nelson" <john at crew-green.com>
> Sent: Sunday, February 10, 2008 12:42 PM
> Subject: Re: RA1772 and 1778 manufacturing dates
>
>
>> Dear John
>>
>> The earliest public reference that I can find to the RA1772 is Roger 
>> Winn's celebrated article "Synthesised communications receiver" in 
>> Wireless World of October 1994, describing the design considerations 
>> for a wideband receiver and, specifically, the RA1772.
>>
>> My glossy RA1772 brochure is copyright dated 1976.
>>
>> Are you aware of the earlier RA1770, using an RA17 type of film scale 
>> rather than LEDs?   I attach separately an extract from Short Wave 
>> Magazine, volume XXIX.  There is no date and I don't have that issue, 
>> but you can work backwards from volume XXXII (which I do have), which 
>> covers March 1974 to February 1975.  That would suggest that the XXIX 
>> volume covered March 1971 to February 1972.  The page number is 757, 
>> and from later volumes that indicates about February - hence about 
>> Feb 1972.  I think I copied this page at the old Patent Office 
>> Library off Chancery Lane in about 1980.
>>
>> The 1772 used the Rafuse switching mixer which, I think, had first 
>> been published in about 1970, and so an initial design reaching 
>> prototype status in about 1972 is not unreasonable.
>>
>> If you look at the 1772 block diagram, you will see that there is a 
>> synthesised VFO covering 3.6 - 4.6MHz.  It may be coincidence that 
>> the VFO in the valved RA117 tunes this range as well, or perhaps not.
>>
>> I have seen no reviews or descriptions of the RA1778 or 1779 in 
>> professional journals.  The copyright date on my glossy brochure for 
>> the RA1779 is 1978. My guess is that the manufacturing start date for 
>> the 1778 is around 1976.
>>
>> Do you know whether there was an RA1773, 1774, 1775, 1776 and 1777?  
>> I think that the 1774 was the maritime version with a narrower 2.35 
>> kHz USB filter in place of the normal 2.75 kHz filter in compliance 
>> with the SOLAS Regs, but I have never seen any.
>>
>> BTW the 1770 series came in a large number of different filter fits 
>> depending on the intended use and customer.  My paperwork here 
>> reveals 47 different fits and there may be more.
>>
>> 73s
>> Michael
>> G8MOB
>>
>
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