[Premium-Rx] Racal RA1772

[Michael O'Beirne]

----- Original Message ----- 
From: "Michael O'Beirne" <michaelob666 at ntlworld.com>
To: "Enrique Fernandez García" <enriqueeeeee2001 at yahoo.es>
Sent: Thursday, August 05, 2010 9:34 PM
Subject: Re: [Premium-Rx] R&S EK 070 Availability?


>
> Dear Enrique
>
> I will give you some advice.  This is based on having owned 4 RA17s with 
> various adaptors, a RA217, RA1217, RA1772, RA1792, RA3701, PR155G, PR2250, 
> PR2280 and STC STR8212 (with complex DSP), not to mention various 
> Eddystones old and new.
>
> The nicest quality AM reception is still the RA1772 in my opinion.  It may 
> have a simple detector and not synchronous nor have all the modern frills 
> such as DSP, but it uses a AM precision detector with less distortion than 
> a conventional diode and sounds good, and my ears are backed up by 
> distortion measurements with professional test gear.
>
> In short, hang on to your RA1772.
>
> The 1772 also gives very low SSB distortion, of around 0.75% THD on a 
> single CW tone.  It's shortcomings are the AGC, which is semi-hang.  The 
> AGC on the RA1792 is better but I don't like that set as much.
>
> The other shortcoming is the PSU.  The +20V regulator is notorious for 
> failing due usually to a dry solder joint caused by the high temperature 
> inside the case.  This regulator provides the voltage reference to the 
> other voltage regulators and its failure causes the whole set to fail. 
> However it's easy to repair, though the mass of wiring gets in the way, 
> but be patient and you will succeed.
>
> The tuning on the 1772 is well weighted and super smooth, eons better than 
> on any Harris or Collins gear.  Almost as good is the RA3701 series, but I 
> still prefer the 1772.
>
> The 2280 is a good set with excellent audio but there are problems.
>
> 1.    Many of the Plessey ICs are no longer available.
> 2.    The tuning seems to have a very very long time constant in the 
> synthesiser.  It sounds distinctly "rubbery" as the signal tunes in.
> 3.    If you have the optional half octave filter module, be prepared to 
> have to change many of the small Clare DIL relays thta switch the ranges. 
> The reason is that the relays carry no DC wetting current and sometimes go 
> open circuit.  This is quite major surgery as there is not much room on 
> the PCB.
> 4.    You will need the rare extender board to work on the module in 
> circuit.
>
>
> 73s
> Michael
> G8MOB
>
>
> ----- Original Message ----- 
> From: "Enrique Fernandez García" <enriqueeeeee2001 at yahoo.es>
> To: <premium-rx at mailman.qth.net>
> Sent: Thursday, August 05, 2010 6:51 PM
> Subject: Re: [Premium-Rx] R&S EK 070 Availability?
>
>
> Hello,
>
> Owning just a RACAL 1772 I have always wanted to buy one too in order to 
> improve the reception with faint AM signals, but I think that the prices 
> have skyrocketed.
> Another interesting option it is a Plessey 2280 but I do not if it could 
> surpass the Racal.
>
> Here you have a nice sample:
>
> http://www.helmut-singer.de/stock/1225203598.html
>
>
>