----- Original Message -----
From: "Chuck Grandgent" <[email protected]>
To: <[email protected]>
Sent: Saturday, July 24, 2010 5:54 PM
Subject: [Drakelist] R4B question about R91
I'm doing the HayseedHamfest recapping on my R4B.
What's the deal with R91, it goes between the two 100uF
sections.
What's it's purpose ?
And, It's listed as 150 ohms, 2 Watts. But in mine, it
looks like
it's more like 1/2 watt, and looks pretty toasted, but it
does test
OK.
I will also say, replacing that can is like doing a root
canal on the R4B.
Got it all done today, but haven't tested it yet, will do
that tomorrow.
Chuck, K1OM
It appers to serve two purposes, one is to drop the 160V
line to 150v and the other is as part of the decouping and
filtering of the 150V line by C-90C. Since the resistor has
a 10 volt drop across it the power is equal to E^2/R about
2/3 of a watt. A half-watt resistor would get quite hot. A
mud (carbon composition) resistor would probably have gone
up in value but a film resistor could take it and stay
stable. Nonetheless, I think I would replace it with a good
film resistor of the specified power capacity.
--
Richard Knoppow
Los Angeles
WB6KBL
[email protected]
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