[ARC5] ARC-5 and SCR-274-N IF Transformers

[D. Platt]

Ken,

As to where exactly;y to taps are, I'd have to really check.  The books 
seem to say "top" in places?  But, your comment also begs another 
question.  It seems that in my trials and tribulations with these 
several receivers, I have indeed cross-pollinated coils.  That is, I've 
mixed the transformers in a given stage (not between stages).  Hence, I 
may well have set up a condition where a single tap SCR-274-N  2nd and 
3rd IF was put in a Navy receiver that "requires" a dual-tapped coil.  
As mentioned, I never saw any difference?  I will have to go back and 
re-order the coil sets and see what I've done, or not done.

Jeep - K3HVG

On 4/16/2014 6:45 PM, Kenneth G. Gordon wrote:
> On 16 Apr 2014 at 17:30, D. Platt wrote:
>
>>> Tapped. In what way? Center-tapped? What? Are the taps connected to
>>> anything? If so, what?
>> One or both coils have a tap near the "top" end of the coil.  The entire
>> coil is the tuned circuit but the primary tap goes to the plate and the
>> secondary goes to the next stage.
> Now that is VERY interesting ! I just checked the schematics and those are
> clearly shown there. I had never noticed that before. Thanks !
>
> In fact, they are drawn as being center-tapped.
>
> In other words, both the plate at one end and the grid at the other are
> "tapped down" on the coils.
>
> This would make both the plate at one end and the grid at the other end
> connected to lower-impedance points on their respective tuned circuits.
>
> I cannot remember at the moment what this does (although I know it is very
> significant) but I SUSPECT that it broadens the IF peak.
>
> I wonder what effect on the IF selectivity there would be if we simply moved
> both connections to the TOPS of each respective IF coil?
>
> Now I am VERY curious.
>
> Ken W7EKB
>
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