From: "Gene McCalmont" 
Subject: [drakelist] Tapping 115VAC from L-4PS
Organization: RowdyHD Inc.


"Gene McCalmont"  made an utterence to the
drakelist gang
----------------------------------------------------------------------
To my Esteemed Colleges:
After some 25+ years of service, my L-4PS power supply for my L-4B started
suffering from electronic arthritis and required a freshening. It now sports
new HV capacitors, bleeder resistors, modern HV diodes with transient
suppression, a "soft start" module from Harbach and other minor mechanical
goodies. It now looks as good as it did originally and functions better than
when new... which, except for the transformer, it is.

However, I am saddened by the fact that this beauty will last only another
25 years before requiring another "freshening." Frankly, what was DRAKE
thinking when they designed and built this equipment in the first place?
I've got shoes older than that! So, I have considered using a fan to help
expel the accumulated heat, thinking it may extend the service life of the
components. And, therein lies the dilemma. 

The supply is wired for 220VAC. I have a 120VAC fan rated at 2100rpm and
370mA. I would like to slow the fan speed somewhat to reduce the noise, and
tap the supply for the 120VAC power. I understand that my 220VAC supply side
is really two 110VAC lines and that I should be able to tap off the switched
side of the 220VAC (after the circuit breaker) to natural and achieve the
desired 110VAC. Therefore, when the amp is switched on, the switched side
energizes and the fan pulls it's required power between the switched side
and natural, but this seems like risky behavior to me. When it comes to HV
power supplies (anything over 12V) I start getting nervous and concerned
that my sweaty palms will provide an excellent return to ground! Currently,
the L-4PS is playing happily downstairs in the shack and the L-4B is
delivering rated power.

What is your experience with cooling the L-4PS? Or, should I, "Don't worry.
Be happy"?

Sincerest regards;
Gene

W5DDW
Gene McCalmont
270 Oak Ridge Ln.
Argyle Texas 76226

----------------------------------------------------------------------
On Behalf of "Gene McCalmont" 
Submissions:        drakelist{at}www.zerobeat.net
Unsubscribe:        majordomo{at}www.zerobeat.net - unsubscribe drakelist in body
Hopelessly Lost:    majordomo{at}www.zerobeat.net - help in body of message
Zerobeat Web Page:  http://www.zerobeat.net
Brought to you courtesy of TLCHost.net  http://www.tlchost.net/
----------------------------------------------------------------------

---