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

[Geoff]

> 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


Yup