Garey Barrell <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Bollini, Maurizio wrote:
"Bollini, Maurizio" <[EMAIL PROTECTED]> made an utterance to the drakelist gang
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Good morning to all,
I have two AC-4 in original conditions, in working order.
I have in mind not only to replace parts but also to improve the
reliability, if possible.
1) Which are the best replacement for rectification diode? In origin
they are B5G5.
a) could I use 1N4007 or BY255 ?
b) is there a better (I mean "more robust") replacement ? To be
in the safest side possible.
c) for those in the HT section, which are in series, is there a
need to put a resistor in parallel ? Reason? Which value/power ?
The B5G5 is a 600V PIV @ 1A diode. The 1N4007 is a suitable
replacement. The 1N5408 is a "more robust" replacement, 1000V PIV @ 3A,
and very inexpensive. No resistors (or capacitors) necessary for
series diodes.
2) Resistors
a) does it make sense to replace them same value increasing the
power rating?
b) R3=100 Ohm on the 250V section
Can't hurt.
i) does it make sense to replace this with a coil of
proper value to improve filtering?
Not really necessary, as the current filtering more than meets the 0.25%
ripple specification.
3) Capacitors
a) does it make sense to increase the capacity to improve
filtering (not so much to avoid an high peak current at sturtup and make
a disaster...)
Again, not necessary for same reason.
Also, look at the AC-4R kit from Mike Bryce at
<http://www.theheathkitshop.com/drakeac4rreplace.html>
Does everything you want to do in a very well designed package, plus
replaces the difficult to find Twist-Lok can capacitors with modern
"snap-in" style.
--
73, Garey - K4OAH
Atlanta
Drake R-4C Service Information CD
http://hr99.home.mindspring.com/R-4C_Servicez
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