[ARC5] 10 meter BC-454 a bit more

[Geoff]

The 8640B and an output meter with AVC off will tell you the gain difference 
if any.
There will always be signal plus noise amplification and the ratio is what 
counts.

Try a 12SG7 in the first IF as I mentioned way back in this thread. It may 
overcome some of the converter noise.

Carl.

----- Original Message ----- 
From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>
To: "Dennis Monticelli" <dennis.monticelli at gmail.com>
Cc: <Arc5 at mailman.qth.net>
Sent: Thursday, March 07, 2013 12:36 AM
Subject: Re: [ARC5] 10 meter BC-454 a bit more


> On 6 Mar 2013 at 21:12, Dennis Monticelli wrote:
>
>> It does sound like the lower gain of the 12SK7 is exposing the input
>> to the noisy mixer.
>
> As I said, I don't "read it" that way: I think the 12SK7 is generating its 
> OWN
> noise which is adding to that of the mixer, and even masking it a bit.
>
> When I have the 12SK7 installed, what I hear is a higher level of what one
> might call "static"....except that it isn't quite static. I've always 
> called that stuff,
> "shot noise".
>
> When I install the 12SG7, the "shot" type noise is pretty much gone, but 
> the
> steady hissing noise, which I am certain is what comes from the mixer,
> becomes more obvious.
>
> From my reading of the tube data sheets, there really isn't any measurable
> difference in the gain of the two tubes.
>
> But I could be wrong...
>
> Ken W7EKB
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