[Boatanchors] F455FA21 and F455FB21 difference

[Michael Bittner]

A picture of the F455FB21 and circuits showing its use in both tube and 
transistor circuits are shown in the Sep 1964 issue of Radio-Electronics 
magazine. However, no impedance values are given.  I also have the F455FA21 
and a data sheet for it showing source and load impedances of 5K minimum for 
parallel resonance and 5K maximum for series resonance.  They both look 
alike to me as designed for tube circuits with parallel resonance or 
transistor circuits with series resonance. They appear to have the same 
mechanical construction with their pins at each end of their plastic 
housings spaced and arranged so that they can plug into standard TO-5, 
3-pin, transistor sockets.

Mike, W6MAB
-
-

----- Original Message ----- 
From: "HL1FB" <yonglee at yonsei.ac.kr>
To: <boatanchors at mailman.qth.net>
Sent: Thursday, March 05, 2015 6:22 AM
Subject: [Boatanchors] F455FA21 and F455FB21 difference


>I have Collins mechanical filters marked F455FA21 and F455FB21.
>
> Anybody knows the difference between these two?
>
> I guess impedance difference but what are the exact values?


---
This email has been checked for viruses by Avast antivirus software.
http://www.avast.com