[ARC5] Re-reading Gordon White article...L-2 in a 'command' receiver

[WA5CAB at cs.com]

As I wrote several months ago in discussions about the as-found resonant 
frequency of L2 in a BC-454 modified to supposedly cover 10 Meters, you 
obviously would not want the self-resonant frequency of any untuned coil in the 
single RF stage to be resonant anywhere in the tuning range.  Reading between 
the lines of what Mike reported out of the ARA/ATA manual, the gain of the 
RF stage must increase with frequency.  Why this would be so I can't say for 
certain but given experience with the BC-611, which has a very short antenna 
for its operating frequency range, it could be at least partially due to 
the effective "gain" versus frequency of the antennas typically used in 
aircraft of the period.

Robert D.

In a message dated 06/06/2013 16:49:53 PM Central Daylight Time, 
kgordon2006 at frontier.com writes: 
> On 6 Jun 2013 at 0:00, Mike Morrow wrote:
> 
> >Ken wrote:
> >
> >>In every case, the resonant frequency of L-2 is way below the
> >>lowest frequency the receiver will tune.
> >
> >Here's what the June 29, 1940, ATA/ARA instruction book has to say
> >about L-2:
> >
> >"C-39 (across L-2 in the 190-550 KC receiver only) serves to tune L-2
> >to a frequency lower than 190 KC, and by so doing increase the
> >amplification of signals at the low frequency end of the tuning range.
> >This assists in producing a reasonably uniform receiver sensitivity
> >over the tuning range.  The plate to screen capacitance of the RF
> >amplifier tube, Type 12SK7, and the wiring capacitance to L-2, perform
> >a corresponding function in all other receivers."
> >
> >That, no doubt, would be the explanation that Dr. Drake would give
> >you.
> >
> >Mike / KK5F
> 
> That makes complete sense, Michael. Thank you.
> 
> Another reason for me to think that those ARC engineers were geniuses...
> 
> It appears that they thought of every possibility and dealt with it 
> appropriately.
> 
> Amazing!
> 
> Ken W7EKB
>