[AMRadio] Resonant Choke bleeder

Mike Sawyer w3slk at hughes.net
Sat Sep 29 20:41:00 EDT 2007

If my old Vo-Tech lessons serve me correctly, you want to be able to bleed 
at least 10% of your total peak current. This will also give you better 
regulation overall.
----- Original Message ----- 
From: Barrie Smith
To: Discussion of AM Radio
Sent: Saturday, September 29, 2007 5:07 PM
Subject: [AMRadio] Resonant Choke bleeder


I'm putting together a resonant power supply with a 9 henry choke, and a .2 
MFD cap that I bought as a pair from PWD about twenty years ago.

These units saw service in a an AM transmitter, using a pair of 450THs in 
the final, the same 20 years ago.

At the time I used them, I know I was able to calculate the required bleeder 
value from information I had at hand.  I don't seem to be able to find that 
information now.

The transformer is 3700 volts, the choke is 9 henry and the cap is .2 MFD. 
I'll be using 70 MFD of oil caps.  I'd like to arrive at about 3300 volts 

Three different sites on the internet give me three different values for the 
bleeder:  66,000 ohms, 78,000 ohms and 89,000 ohms.

One of them may be correct!

I'd like to bleed as lightly as possible, but I sure don't want the voltage 
to soar.

Any help appreciated.

73, Barrie, W7ALW 

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