[R-390] Z503 Replacement

[rbethman]

On 4/2/2011 4:06 PM, Drew P. wrote:
> <SNIP>

>   Remember, Z503, while adjustable, doesn't even have a hole in the can for adjustment; this shows the relatively "loose" nature of the part.
Then apparently one cannot read the alignment instructions properly, 
even in Roger's VERY recent series, nor can they follow the changes made 
over their service life.  Holes were drilled in the top of the cans to 
allow for adjustment!
> I believe that Z503's coil was "over engineered" with the pot core, pie windings, and epoxy simply for manufacturing convenience - to enable it to be built on the same production line as the already-proven IF transformers (which are also somewhat similarly constructed) and without incurring need for extra source component inventory.
Read the quotation from the cost reduction analysis report - on-line, 
provided by Bill Hawkins.
> Insofar as shielding provided by the pot core is concerned, Z503 is already in a can - how much more shielding do you need? I see little reason why the "guts" of Z503 could not be replaced with those out of a tube-type 455 KC IF can salvaged from an AA5, those from a detector transformer just to be proper.
They had DEFINITE reasons for the design.  Other home-brewed ones may 
well work.  How much work and measurement equipment do we ALL need to have?

Bob - N0DGN