[Premium-Rx] The Ghost of Racal Past

[Michael O'Beirne]

Dear Ron

I am guessing that the 5MHz standard in your Ra3711 is the Racal-Dana 9422. 
If it is, the bad news is that they do fail far more often then others.

I had a problem with mine in the Ra1792.  The answer is either to resolder 
all the internal connections (but you may find that the crystal has aged 
beyond adjustment) or to get another one.  They are quite easy to find on 
eBay.  My replacement one cost £25.  The original price was probably 10 
greater.

Perhaps an easier solution is to feed it from an external standard such as 
an HP105B.

The 9420 in my much older RA1772 is absolutely fine, and the TCXOs (made I 
think by ITT) are also very reliable.

73s
Michael
G8MOB

----- Original Message ----- 
From: "Ron Ott" <ronott at sbcglobal.net>
To: <Premium-Rx at mailman.qth.net>
Sent: Thursday, July 12, 2012 10:16 PM
Subject: [Premium-Rx] The Ghost of Racal Past


My 3711 has been visited by gremlins from the Ghost of Racal Past. The 
fundamental problem with my 3711 was the internal 5MHz reference 
osciallator. As a result, LO injection levels were low and the BITE 
indicated a couple faults: low 2nd LO level and RX gain failure (but not a 
reference oscillator problem). The 3701 and 3711 receivers are different in 
some important ways and my 3701 manual raised more questions about LO 
frequencies and voltage measurements than it answered.

Nevertheless I eventually wound up checking the 5MHz Reference Oscillator 
output that turned out to be the problem. Using my HP sig gen as an external 
reference the 3711 came to life and also passed the BITE test.

But more gremlins: I switched back to the internal reference oscillator to 
check whether the BITE errors would come back, and the 3711 still works 
fine. For how long, I don't know, but I now know there is some funny 
business with the reference oscillator (Bad cable or connector??? Int/Ext 
switch contacts??? Who knows?)

Thanks to all who came to my assistance with Racal information, I'm in a 
good place with the 3711 right now and hoping to stay there. Let's hope the 
Ghost of Racal Future is kinder.

73, Ron W6XY