[ARC5] BC-455 IFT - measurements

[Mike Hanz]

As a veteran of 40 years dealing with contract specifications from the 
government side of the fence, I suspect that their design had more to do 
with meeting a specification for selectivity, and doing it in the most 
economical way.  That's what engineering is all about.  Why price 
yourself out of a competitive acquisition by doing more than the 
contract requires?  In a 10,000 receiver purchase, the difference in 
contract price between including an adjustable cap and none at all can 
mean the difference between getting the contract and not.  The 
selectivity is reflected in the manuals, and I would bet a beer that it 
matches the original Navy contract specs.

  - Mike  KC4TOS

On 10/29/2014 12:42 PM, Kenneth G. Gordon wrote:
> On 29 Oct 2014 at 7:47, Fuqua, Bill L wrote:
>
>> I should have said that C14 couples signal from L6 to grid of first IF.
>> C14 is 180pf also but it is in series with much less capacitance that consist of
>> Grid to ground capacitance of first IF in parallel with the interwinding
>> capacitance of the L7 and stray capacitance of wiring to ground.
>>    Plate capacitance to ground of mixer is directly across L6 more or less.
> Yes. I noticed all that too.
>
> I STILL cannot understand why they did it that way...
>
> Was it really that necessary to have such "poor" (to us) selectivity?
>
> Ken W7EKB