[ARC5] S+N/N ratio results..more.

Kenneth G. Gordon kgordon2006 at frontier.com
Sun Jun 16 21:33:00 EDT 2013


On 16 Jun 2013 at 11:01, Geoff wrote:

> At 2mc I doubt if the tube input C difference has anything to do with
> it since it is such a small amount. OTOH the 12SH7 input admittance
> may be loading down the input coil as happens when its predecessor,
> the 6AC7, is swapped in place of the SK7, SG7, etc.
> 
> At 2mc a 6AB7 might prove useful.

Gordon White used one of those in an "ARC-5" he modified to tune to 40 
MHz.  "back in the day".

I'll get a couple to see what difference it makes.

At this point, my conclusion is that tube-swaps at 2 MHz don't really make 
any real difference.

Ken W7EKB 


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