{Collins} Collins Specifications for KWM-380 Finals


Here is the info that quite a few you have been asking me for regarding 
the actual Collins specifications for the transistors used in the Final 
PA of the KWM/HF-380.  This came from Rockwell/Collins' archives.  If I 
find out more info, I'll pass it along!


The Motorola referenced part is the MRF-421 - subject to all the
requirements in the Collins specifications.  Matched pairs are selected 
as follows: The top of the 352-1144-010 transistors will have a "letter" 
printed on it.  Both transistors must bear the same letter in order to 
be a matched pair.  The letter denotes the Beta (dc gain when Ic=5.0 
amp, Vce=5.0 Vdc).  The Beta values corresponding to the letters are as 

A = 9-17
B = 15-23
C = 20-32
D = 28-42
E = 38-52
F = 48-63
G = 57-78
H = 72-93

Normal MRF-421's will not have the letter on the lids, so matching them 
up will take the proper equipment and knowledge.

BTW, you will see this chart along with the corresponding "color dot" 
codes in RF Parts' web site.

Thanks to Rod Blocksome for coming up with the Collins info!
Floyd Soo, W8RO
President, HI-RES Communications, Inc.
President, Collins Collectors Association (member #2)

Sponsored by the Collins Collectors Association http://www.collinsradio.org
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