[ARC5] Selectivity and the BC-455

[Mike Feher]

Ian - you may want to try and measure that winding again. 2 mH is a lot and
would not be used at RF frequencies. Just compare it to a typical 2.5 mH RF
choke which has multiple pi sections and is used as a choke to prevent
conductive RF leakage. 73 - Mike 

Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960 


-----Original Message-----
From: ARC5 [mailto:arc5-bounces at mailman.qth.net] On Behalf Of Ian Wilson
Sent: Saturday, October 25, 2014 1:27 PM
To: Kenneth G Gordon
Cc: ARC5
Subject: Re: [ARC5] Selectivity and the BC-455

Update on my measurements: I went through my ARC-5 spares box and discovered
three 7277 (1st) IFTs. On closer inspection, two of these have been
modified. The third unit had unbroken red paint over the screws so I think
it's safe to assume this one is kosher.

The pi winding in the intact 7277 measures about 2mH. This is drastically
different from the other two: 60uH and 180uH. My guess is that someone was
trying to turn the second winding into a tuned one.

So, I no longer think that the pie-wound winding was meant to resonate
approximately with the input capacitance of the second stage.

73, ian K3IMW