[ARC5] Selectivity and the BC-455

[WA5CAB--- via ARC5]

Here is, as saliors used to say, the "straight skinny".  I have and have 
just gone through the manuals on all Type-K derived Command Sets.  All IFT's 
in all models of all sets have two coils in all IFT's.  In all IFT's up 
through 1415 KC, both the primary and the secondary coils are pie-wound and both 
are tuned.

In all 4200 KC and all 2830 KC IFT's except those in R-27/ARC-5, the 
primary coil is single layer close wound and is tuned.  The secondary is pie-wound 
and untuned (or fix tuned).  In all IFT's in all R-27/ARC-5 (both before 
and after 01 January 1945), the primary and secondary are both pie-wound and 
both are tuned.

Probably someone with the necessary parts and the time should take a 
BC-455, carefully alingn it, and measure the 6db and 60db bandwidths.  Then 
substitute all three IFT's with a set from an R-27, re-align it and repeat the 
bandwidth tests.

Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480

In a message dated 10/24/2014 13:15:36 PM Central Daylight Time, 
jeepp at comcast.net writes: 
> Ken,
> 
> Now that's a new twist on the subject.  Truth told, I have never seen a 
> single-coil ARC-5/274-N receiver, but then again, its only recently that 
> I've been actually disassembling them.   If there is only one coil, no 
> wonder the selectivity is "less than what might be desired".   Which 
> manual carries that design, if you or anyone can pass on?
> 
> Regards
> 
> Jeep - K3HVG
>