[R-390] R392 Audio

[Meir WF2U]

For those who can't get the official issue SS module schematic via the link
in my previous message, here is the same link, shortened by TinyURL:
http://tinyurl.com/pmzzbgu . Long URL's sometimes don't go through some
email clients, but even then it can be just copied and pasted into the
browser. TinyURL saves you that operation and links directly.

73, Meir WF2U
Landrum, SC

-----Original Message-----
From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]
On Behalf Of Charles Steinmetz
Sent: Friday, January 24, 2014 12:25 PM
To: 390 list
Subject: Re: [R-390] R392 Audio

Tom wrote:

>Charles was there not a solid state module developed by the military 
>for the 392?  How did it work?

Yes, indeed.  It is documented in Figure 20 of the 1961 R392 manual, 
TM-11-5820-334-35.  Meir posted some information about it, including 
the fact that the external feedback resistor (R629) must be removed 
when the Solid State Audio Module is installed (because it has too 
much phase shift to remain stable in a global feedback loop).  This 
means that the preceding audio stages (V606 and V607) are no longer 
inside a feedback loop.

IMO, it is a lot better than the original 26A7 circuit, although it 
is a bit noisy.

Best regards,

Charles